Fix nullary function declarations

Reviewed-on: #1

core/bus.c

@@ -95,16 +95,16 @@ static int32_t busReadMisc(VB *sim, uint8_t address, int type) {
 
     /* Access by register */
     switch (address >> 2 & 15) {
-        case 0x00>>2: break; /* CCR */
+        case 0x00>>2: return extReadCCR(sim);                      /* CCR */
-        case 0x04>>2: break; /* CCSR */
+        case 0x04>>2: return extReadCCSR(sim);                     /* CCSR */
-        case 0x08>>2: break; /* CDTR */
+        case 0x08>>2: return sim->ext.cdtr;                        /* CDTR */
-        case 0x0C>>2: break; /* CDRR */
+        case 0x0C>>2: return sim->ext.cdrr;                        /* CDRR */
         case 0x10>>2: return sim->pad.sdlr;                        /* SDLR */
         case 0x14>>2: return sim->pad.sdhr;                        /* SDHR */
         case 0x18>>2: return sim->tmr.counter      & 0xFF;         /* TLR */
         case 0x1C>>2: return sim->tmr.counter >> 8 & 0xFF;         /* THR */
         case 0x20>>2: return tmrReadControl(sim);                  /* TCR */
-        case 0x24>>2: return sim->wcr;                     /* WCR */
+        case 0x24>>2: return sim->wcr.exp1w << 1 | sim->wcr.rom1w; /* WCR */
         case 0x28>>2: return padReadControl(sim);                  /* SCR */
     }
 
@@ -123,15 +123,16 @@ static void busWriteMisc(VB *sim, uint8_t address, int type, int32_t value) {
 
     /* Access by register */
     switch (address >> 2 & 15) {
-        case 0x00>>2: break; /* CCR */
+        case 0x00>>2: extWriteCCR (sim, value);    break; /* CCR */
-        case 0x04>>2: break; /* CCSR */
+        case 0x04>>2: extWriteCCSR(sim, value);    break; /* CCSR */
-        case 0x08>>2: break; /* CDTR */
+        case 0x08>>2: sim->ext.cdtr = value;       break; /* CDTR */
-        case 0x0C>>2: break; /* CDRR */
         case 0x18>>2: tmrWriteLow    (sim, value); break; /* TLR */
         case 0x1C>>2: tmrWriteHigh   (sim, value); break; /* THR */
         case 0x20>>2: tmrWriteControl(sim, value); break; /* TCR */
-        case 0x24>>2: sim->wcr = value & 3;        break; /* WCR */
         case 0x28>>2: padWriteControl(sim, value); break; /* SCR */
+        case 0x24>>2:                                     /* WCR */
+            sim->wcr.exp1w = value >> 1 & 1;
+            sim->wcr.rom1w = value      & 1;
     }
 
 }
@@ -158,6 +159,8 @@ static void busRead(VB *sim, uint32_t address, int type, int32_t *value) {
 
         case 2: /* Misc. I/O */
             *value = busReadMisc(sim, address, type);
+            if (type == VB_S8)
+                *value = (int8_t) *value;
             break;
 
         case 3: break; /* Unmapped */

core/cpu.c

@@ -91,11 +91,6 @@
 #define CPU_XORBSU   82
 #define CPU_XORNBSU  83
 
-/* Functional operand types */
-#define CPU_LITERAL  0
-#define CPU_MEMORY   1
-#define CPU_REGISTER 2
-
 /* Bit string operations */
 #define CPU_AND_BS  0
 #define CPU_ANDN_BS 1
@@ -239,7 +234,7 @@ static int cpuOnExecute(VB *sim) {
     #define VB_ON_READ VB_DIRECT_READ
 #endif
 static int cpuRead(VB *sim, uint32_t address, int type, int32_t *value) {
-    uint32_t cycles = 4; /* TODO: Research this */
+    uint32_t cycles = 0; /* TODO: Research this */
 
     /* Retrieve the value from the simulation state directly */
     busRead(sim, address, type, value);
@@ -294,7 +289,7 @@ static int cpuReadFetch(VB *sim, int fetch, uint32_t address, int32_t *value) {
 #endif
 static int cpuWrite(VB *sim, uint32_t address, int type, int32_t value) {
     int      cancel = 0;
-    uint32_t cycles = 3; /* TODO: Research this */
+    uint32_t cycles = 0; /* TODO: Research this */
 
     /* Reset pseudo-halt */
     if (sim->ph.enabled)
@@ -500,7 +495,7 @@ static int cpuException(VB *sim) {
         sim->cpu.eipc     = sim->cpu.pc;
         sim->cpu.psw.ep   = 1;
         sim->cpu.nextPC   = 0xFFFF0000 |
-            ((cause & 0xFFF0) == 0xFF60 ? 0xFF60 : cause & 0xFFF0);
+            ((cause & 0xFFF0) == 0xFF70 ? 0xFF60 : cause & 0xFFF0);
     }
 
     /* All exceptions */
@@ -1642,6 +1637,7 @@ static void cpuSUBF_S(VB *sim) {
 /* TRAP */
 static void cpuTRAP(VB *sim) {
     sim->cpu.clocks += cpuClocks(15);
+    sim->cpu.pc     += 2;
     cpuThrow(sim, 0xFFA0 + cpuGetImm5U(sim));
 }
 

core/ext.c

@@ -0,0 +1,164 @@
+/* This file is included into vb.c and cannot be compiled on its own. */
+#ifdef VBAPI
+
+
+
+/***************************** Callback Handlers *****************************/
+
+/* Prepare to handle an exception */
+#ifndef VB_DIRECT_LINK
+    #define VB_ON_LINK sim1->onLink
+#else
+    extern int VB_DIRECT_LINK(VB *, VB *, uint8_t *, uint8_t *);
+    #define VB_ON_LINK VB_DIRECT_LINK
+#endif
+static int extOnLink(VB *sim1, VB *sim2, uint8_t *value1, uint8_t *value2) {
+    return sim1->onLink != NULL && VB_ON_LINK(sim1, sim2, value1, value2);
+}
+#undef VB_ON_LINK
+
+
+
+/***************************** Library Functions *****************************/
+
+/* Process component */
+static int extEmulate(VB *sim, uint32_t clocks) {
+    VB     *peer;      /* Communication peer */
+    VB     *sims[2];   /* Communication peers */
+    uint8_t values[2]; /* Transmission values */
+    int     x;         /* Iterator */
+
+    /* Communication will not occur */
+    if (!sim->ext.c_stat || sim->ext.c_clk_sel)
+        return 0;
+
+    /* Communication completes after time to process */
+    if (sim->ext.clocks > clocks) {
+        sim->ext.clocks -= clocks;
+        return 0;
+    }
+
+    /* Exchange transmission data */
+    sims  [0] = sim;
+    sims  [1] = sim->peer;
+    values[0] = sim->ext.cdtr;
+    values[1] = sim->peer == NULL ? 0 : sim->peer->ext.cdtr;
+    if (extOnLink(sim, sim->peer, &values[0], &values[1]))
+        return 1;
+
+    /* Update state */
+    for (x = 0; x < 2; x++) {
+        sim  = sims[x];
+        peer = sims[x ^ 1];
+        if (sim  == NULL)
+            break;
+        if (peer == NULL)
+            peer = sim;
+
+        /* Registers */
+        sim->ext.cdrr    = values[x ^ 1];
+        sim->ext.c_irq  |= !sim->ext.c_int_inh;
+        sim->ext.c_stat  = 0;
+        sim->ext.cc_rd   = sim->ext.cc_wr  & peer->ext.cc_wr;
+        sim->ext.cc_smp  = sim->ext.cc_sig & peer->ext.cc_sig & sim->ext.cc_rd;
+        sim->ext.cc_irq |= !sim->ext.cc_int_inh &&
+            sim->ext.cc_smp == sim->ext.cc_int_lev;
+
+        /* Interrupt */
+        if (sim->ext.c_irq | sim->ext.cc_irq)
+            sim->cpu.irq |= 0x0008;
+    }
+    return 0;
+}
+
+/* Read a value from CCR */
+static int32_t extReadCCR(VB *sim) {
+    return 0x6D |
+        sim->ext.c_int_inh << 7 |
+        sim->ext.c_clk_sel << 4 |
+        sim->ext.c_stat    << 1
+    ;
+}
+
+/* Read a value from CCSR */
+static int32_t extReadCCSR(VB *sim) {
+    sim->ext.cc_rd = sim->ext.cc_wr &
+        (sim->peer == NULL ? 1 : sim->peer->ext.cc_wr);
+    return 0x60 |
+        sim->ext.cc_int_inh << 7 |
+        sim->ext.cc_int_lev << 4 |
+        sim->ext.cc_sig     << 3 |
+        sim->ext.cc_smp     << 2 |
+        sim->ext.cc_wr      << 1 |
+        sim->ext.cc_rd
+    ;
+}
+
+/* Simulate a hardware reset */
+static void extReset(VB *sim) {
+
+    /* Normal */
+    sim->ext.c_clk_sel  = 0;
+    sim->ext.c_int_inh  = 0;
+    sim->ext.c_stat     = 0;
+    sim->ext.cc_int_inh = 1;
+    sim->ext.cc_int_lev = 1;
+    sim->ext.cc_sig     = 1;
+    sim->ext.cc_wr      = 1;
+    sim->ext.cdrr       = 0x00;
+    sim->ext.cdtr       = 0x00;
+
+    /* Other */
+    sim->ext.c_irq  = 0;
+    sim->ext.cc_irq = 0;
+}
+
+/* Determine how many clocks are guaranteed to process */
+static uint32_t extUntil(VB *sim, uint32_t clocks) {
+    return !sim->ext.c_stat || sim->ext.c_clk_sel || clocks < sim->ext.clocks ?
+        clocks : sim->ext.clocks;
+}
+
+/* Write a value to CCR */
+static void extWriteCCR(VB *sim, uint8_t value) {
+
+    /* Configure state */
+    sim->ext.c_int_inh = value >> 7 & 1;
+    sim->ext.c_clk_sel = value >> 4 & 1;
+
+    /* Acknowledge interrupt */
+    if (sim->ext.c_int_inh) {
+        sim->ext.c_irq = 0;
+        if (!sim->ext.cc_irq)
+            sim->cpu.irq &= ~0x0008;
+    }
+
+    /* Do not initiate a communication */
+    if (sim->ext.c_stat || (value & 0x04) == 0) /* C-Start */
+        return;
+
+    /* Initiate a communication */
+    sim->ext.c_stat = 1;
+    sim->ext.clocks = 3200; /* 160us */
+}
+
+/* Write a value to CCSR */
+static void extWriteCCSR(VB *sim, uint8_t value) {
+
+    /* Configure state */
+    sim->ext.cc_int_inh = value >> 7 & 1;
+    sim->ext.cc_int_lev = value >> 4 & 1;
+    sim->ext.cc_sig     = value >> 3 & 1;
+    sim->ext.cc_wr      = value >> 1 & 1;
+
+    /* Acknowledge interrupt */
+    if (!sim->ext.cc_int_inh)
+        return;
+    sim->ext.cc_irq = 0;
+    if (!sim->ext.c_irq)
+        sim->cpu.irq &= ~0x0008;
+}
+
+
+
+#endif /* VBAPI */

core/game-pad.c

@@ -9,12 +9,12 @@
 static void padEmulate(VB *sim, uint32_t clocks) {
 
     /* No hardware read in progress */
-    if (sim->pad.si_stat == 0)
+    if (!sim->pad.si_stat)
         return;
 
     /* Hardware read completes after time to process */
-    if (sim->pad.si_stat > clocks) {
+    if (sim->pad.clocks > clocks) {
-        sim->pad.si_stat -= clocks;
+        sim->pad.clocks -= clocks;
         return;
     }
 
@@ -38,7 +38,7 @@ static int32_t padReadControl(VB *sim) {
         sim->pad.k_int_inh << 7 |
         sim->pad.para_si   << 5 |
         sim->pad.soft_ck   << 4 |
-        !!sim->pad.si_stat << 1 |
+        sim->pad.si_stat   << 1 |
         sim->pad.s_abt_dis
     ;
 }
@@ -78,7 +78,8 @@ static void padWriteControl(VB *sim, uint8_t value) {
         sim->pad.si_stat == 0 && /* No hardware read underway */
         !sim->pad.s_abt_dis      /* Hardware reads enabled */
     ) {
-        sim->pad.si_stat = 10240; /* 512us */
+        sim->pad.clocks  = 10240; /* 512us */
+        sim->pad.si_stat = 1;
         sim->pad.step    = 0;     /* Abort software read */
     }
 
@@ -86,7 +87,7 @@ static void padWriteControl(VB *sim, uint8_t value) {
     sim->pad.para_si = value >> 5 & 1;
     if (
         sim->pad.para_si &&
-        sim->pad.si_stat == 0 /* No hardware read underway */
+        !sim->pad.si_stat /* No hardware read underway */
     ) sim->pad.step = 32;
 
     /* Signal a bit for a software read */
@@ -107,8 +108,8 @@ static void padWriteControl(VB *sim, uint8_t value) {
 
 /* Determine how many clocks are guaranteed to process */
 static uint32_t padUntil(VB *sim, uint32_t clocks) {
-    return sim->pad.si_stat != 0 && sim->pad.si_stat < clocks ?
+    return sim->pad.si_stat && sim->pad.clocks < clocks ?
-        sim->pad.si_stat : clocks;
+        sim->pad.clocks : clocks;
 }
 
 

core/pseudo-halt.c

@@ -142,6 +142,7 @@ static uint32_t phDPSTTS(VB *sim) {
         case 3: /* 8ms - L*BSY falling edge */
         case 6: /* 13ms-18ms - Display right frame buffer */
         case 7: /* 18ms - R*BSY falling edge */
+        case 8: /* 20ms - Display interval complete */
             return sim->vip.dp.until;
     }
     /* case 1: 3ms - L*BSY rising edge */

core/timer.c

@@ -5,6 +5,15 @@
 
 /***************************** Module Functions ******************************/
 
+/* Compute clocks until the next decrement to zero */
+static uint32_t tmrGetUntil(VB *sim) {
+    uint32_t fullTick = sim->tmr.t_clk_sel ? 400 : 2000;
+    uint32_t thisTick = sim->tmr.clocks +
+        (sim->tmr.t_clk_sel ? 0 : 400 * (4 - sim->tmr.tick20));
+    return thisTick + fullTick *
+        (sim->tmr.counter == 0 ? sim->tmr.reload : sim->tmr.counter - 1);
+}
+
 /* Update the counter to a new value */
 static void tmrUpdate(VB *sim, uint16_t value) {
     if (value == 0 && sim->tmr.counter != 0) {
@@ -23,10 +32,6 @@ static void tmrUpdate(VB *sim, uint16_t value) {
 /* Process component */
 static void tmrEmulate(VB *sim, uint32_t clocks) {
 
-    /* Timer is disabled */
-    if (!sim->tmr.t_enb)
-        return;
-
     /* Process all clocks */
     for (;;) {
 
@@ -40,13 +45,20 @@ static void tmrEmulate(VB *sim, uint32_t clocks) {
         /* Advance forward the component's number of clocks */
         clocks          -= sim->tmr.clocks;
         sim->tmr.until  -= sim->tmr.clocks;
-        sim->tmr.clocks = sim->tmr.t_clk_sel ? 400 : 2000;
+        sim->tmr.clocks  = 400;
+        sim->tmr.tick20 += sim->tmr.tick20 == 4 ? -4 : 1;
+
+        /* Do not decrement counter */
+        if (
+            !sim->tmr.t_enb ||
+            (!sim->tmr.t_clk_sel && sim->tmr.tick20 != 0)
+        ) continue;
 
         /* Advance to the next counter value */
         tmrUpdate(sim, sim->tmr.counter == 0 ?
             sim->tmr.reload : sim->tmr.counter - 1);
         if (sim->tmr.counter == 0)
-            sim->tmr.until = sim->tmr.clocks * ((uint32_t)sim->tmr.reload + 1);
+            sim->tmr.until = tmrGetUntil(sim);
     }
 
 }
@@ -71,8 +83,10 @@ static void tmrReset(VB *sim) {
     sim->tmr.z_stat    = 0;
 
     /* Other */
+    sim->tmr.clocks  = 400;
     sim->tmr.counter = 0xFFFF;
     sim->tmr.reload  = 0x0000;
+    sim->tmr.tick20  = 0;
 }
 
 /* Determine how many clocks are guaranteed to process */
@@ -88,14 +102,27 @@ static void tmrWriteControl(VB *sim, uint8_t value) {
     if (
         (value & 0x04) && /* Z-Stat-Clr */
         (
-            sim->tmr.counter != 0 ||
+            !sim->tmr.t_enb ||
-            !sim->tmr.t_enb
+            (
+                sim->tmr.counter != 0 &&
+                !(value & 0x01) /* T-Enb */
+            )
         )
     ) {
         sim->tmr.z_stat = sim->tmr.counter != 0;
         sim->cpu.irq   &= ~0x0002;
     }
 
+    /* Hardware bug: decrement on switch to 20us mode */
+    if (
+        !sim->tmr.t_clk_sel &&
+        (value & 0x10)      && /* T-Clk-Sel */
+        sim->tmr.tick20 != 0
+    ) {
+        tmrUpdate(sim, sim->tmr.counter == 0 ?
+            sim->tmr.reload : sim->tmr.counter - 1);
+    }
+
     /* Parse fields */
     sim->tmr.t_clk_sel = value >> 4 & 1;
     sim->tmr.tim_z_int = value >> 3 & 1;
@@ -105,10 +132,8 @@ static void tmrWriteControl(VB *sim, uint8_t value) {
     if (!sim->tmr.tim_z_int)
         sim->cpu.irq &= ~0x0002;
 
-    /* Configure countdowns */
+    /* Configure state */
-    sim->tmr.clocks = sim->tmr.t_clk_sel ? 400 : 2000;
+    sim->tmr.until = tmrGetUntil(sim);
-    sim->tmr.until  = sim->tmr.clocks * (sim->tmr.counter == 0 ?
-        (uint32_t) sim->tmr.reload + 1 : sim->tmr.counter);
 
     /* TODO: Will Z-Stat raise an interrupt when Tim-Z-Int is set? */
 }
@@ -117,12 +142,14 @@ static void tmrWriteControl(VB *sim, uint8_t value) {
 static void tmrWriteHigh(VB *sim, uint8_t value) {
     sim->tmr.reload = (uint16_t) value << 8 | (sim->tmr.reload & 0x00FF);
     tmrUpdate(sim, sim->tmr.reload);
+    sim->tmr.until  = tmrGetUntil(sim);
 }
 
 /* Write to the low data register */
 static void tmrWriteLow(VB *sim, uint8_t value) {
     sim->tmr.reload = (sim->tmr.reload & 0xFF00) | value;
     tmrUpdate(sim, sim->tmr.reload);
+    sim->tmr.until  = tmrGetUntil(sim);
 }
 
 

core/vb.c

@@ -8,8 +8,11 @@
 
 /*********************************** Types ***********************************/
 
-/* Output image */
+/* VIP BG map cell */
-typedef uint8_t Pixels[2][384*224];
+typedef struct {
+    uint8_t *palette; /* Points to a VB.vip.gplt */
+    uint8_t *pixels;  /* Points to a VB.vip.characters */
+} Cell;
 
 /* VSU channel */
 typedef struct {
@@ -26,6 +29,7 @@ typedef struct {
 
         /* Other state */
         uint32_t clocks;  /* Clocks until modification */
+        uint8_t  modmask; /* Modifications masked */
         uint8_t  reload;  /* Automatic reload value */
     } env;
 
@@ -64,9 +68,58 @@ typedef struct {
     } wave;
 
     /* Other state */
-    uint32_t clocks; /* Clocks until next sample */
+    uint32_t clocks;  /* Clocks until next wave or noise sample */
+    uint8_t  freqmod; /* Frequency modifications are active */
+    uint32_t until;   /* Clocks until channel component update */
 } Channel;
 
+/* VIP character (hflp << 1 | vflp) */
+typedef uint8_t Character[4][64];
+
+/* VIP object */
+typedef struct {
+    Cell    cell; /* BG map-like attributes */
+    int16_t jp;   /* Parallax */
+    int16_t jx;   /* Screen base X */
+    int16_t jy;   /* Screen Y */
+    uint8_t lron; /* Visible in left and right images */
+} Object;
+
+/* Output image */
+typedef uint8_t Pixels[2][384*224];
+
+/* VIP world */
+typedef struct {
+
+    /* Attributes */
+    uint8_t  bgm;       /* Mode */
+    uint8_t  end;       /* Control world */
+    int16_t  gp;        /* World parallax */
+    int16_t  gx;        /* World base X */
+    int16_t  gy;        /* World Y */
+    int16_t  mx;        /* Scroll base X */
+    int16_t  mp;        /* Scroll parallax */
+    int16_t  my;        /* Scroll Y */
+    uint8_t  over;      /* Use overplane */
+    Cell    *overplane; /* Overplane cell */
+
+    /* Non-attributes */
+    Cell    *bg[64];    /* Background arrangement */
+    int32_t  bgHeight;  /* Height of background in pixels */
+    uint32_t bgMaskX;   /* Horizontal background mask */
+    uint32_t bgMaskY;   /* Vertical background mask */
+    uint32_t bgShift;   /* Bits to shift when selecting a BG map */
+    int32_t  bgWidth;   /* Width of background in pixels */
+    uint32_t hAffine;   /* H for affine mode */
+    uint32_t hNaffine;  /* H for not affine mode */
+    uint32_t height;    /* Height of world in pixels */
+    uint8_t  lron;      /* Visible in left and right images */
+    uint32_t paramBase; /* H-bias and affine parameter address */
+    uint32_t wAffine;   /* W for affine mode */
+    uint32_t wNaffine;  /* W for not affine mode */
+    uint32_t width;     /* Width of world in pixels */
+} World;
+
 /* Simulation state */
 struct VB {
 
@@ -146,6 +199,28 @@ struct VB {
         int      step;      /* Operation sub-task ID */
     } cpu;
 
+    /* Communication port */
+    struct {
+
+        /* Register state */
+        uint8_t c_clk_sel;  /* Transmission clock source */
+        uint8_t c_int_inh;  /* Interrupt acknowledge/disable */
+        uint8_t c_stat;     /* Communication is underway */
+        uint8_t cc_int_inh; /* Interrupt acknowledge/disable */
+        uint8_t cc_int_lev; /* Interrupt condition */
+        uint8_t cc_rd;      /* Manual read */
+        uint8_t cc_sig;     /* Automatic write */
+        uint8_t cc_smp;     /* Automatic read */
+        uint8_t cc_wr;      /* Manual write */
+        uint8_t cdrr;       /* Data received */
+        uint8_t cdtr;       /* Data to transmit */
+
+        /* Other state */
+        int8_t   c_irq;  /* COM interrupt request */
+        int8_t   cc_irq; /* COMCNT interrupt request */
+        uint32_t clocks; /* Master clocks to wait */
+    } ext;
+
     /* Game pad */
     struct {
 
@@ -159,6 +234,7 @@ struct VB {
         uint8_t  soft_ck;   /* Controller communication signal */
 
         /* Other state */
+        uint32_t clocks; /* Master clocks to wait */
         uint16_t keys;   /* Next input bits */
         int      step;   /* Software read processing phase */
     } pad;
@@ -176,6 +252,7 @@ struct VB {
         uint32_t clocks;  /* Master clocks to wait */
         uint16_t counter; /* Current counter value */
         uint16_t reload;  /* Reload counter value */
+        uint8_t  tick20;  /* Current 20-microsecond tick */
         uint32_t until;   /* Clocks until interrupt condition */
     } tmr;
 
@@ -236,6 +313,7 @@ struct VB {
             int      frame;    /* FRMCYC counter */
             int32_t  halfword; /* Current output halfword offset */
             int      step;     /* Processing phase */
+            uint8_t  toggle;   /* Switch frame buffers next frame */
             uint32_t until;    /* Clocks until interrupt condition */
         } xp;
 
@@ -250,12 +328,17 @@ struct VB {
         uint16_t spt[4];     /* Object control */
 
         /* Rendering shadow memory */
+        uint8_t  buffer;            /* Output buffer */
         uint16_t halfwords[384*28]; /* Output timing by 1x8 halfword */
         Pixels   output[2];         /* Output images, row-major */
         Pixels   shadow;            /* Drawing shadow image, column-major */
 
         /* Other state */
+        Cell      cells[0x10000];   /* Pre-computed BG map attributes */
+        Character characters[2048]; /* Pre-computed character pixels */
+        Object    objects[1024];    /* Pre-computed object attributes */
         uint8_t   ram[0x40000];     /* Video memory */
+        World     worlds[32];       /* Pre-computed world attributes */
     } vip;
 
     /* VSU */
@@ -278,6 +361,8 @@ struct VB {
 
             /* Other state */
             uint32_t clocks;   /* Clocks until modification */
+            uint8_t  freqmask; /* Frequency mask */
+            uint8_t  modmask;  /* Modifications masked */
             uint16_t next;     /* Next frequency value */
             int      sample;   /* Current sample index */
         } freqmod;
@@ -296,9 +381,10 @@ struct VB {
         struct {
             float    i1[2];    /* Previous analog input sample */
             float    o1[2];    /* Previous analog output sample */
-            uint32_t capacity; /* Number of audio frames in samples */
+            unsigned capacity; /* Number of audio frames in output buffer */
-            uint32_t offset;   /* Position in output buffer */
+            unsigned offset;   /* Position in output buffer */
-            int16_t *samples;  /* Output memory */
+            void    *samples;  /* Output buffer */
+            int      type;     /* Output data type */
         } out;
 
         /* Memory */
@@ -310,6 +396,12 @@ struct VB {
         int      sample; /* Output sample index, period 417 */
     } vsu;
 
+    /* Wait controller */
+    struct {
+        uint8_t exp1w; /* Cartridge expansion 1-wait */
+        uint8_t rom1w; /* Cartridge ROM 1-wait */
+    } wcr;
+
     /* Pseudo-halt */
     struct {
         uint32_t address;   /* Monitor address */
@@ -335,7 +427,6 @@ struct VB {
     } ph;
 
     /* Other state */
-    uint8_t wcr;           /* Wait controller state */
     uint8_t wram[0x10000]; /* System RAM */
 
     /* Application data */
@@ -343,9 +434,11 @@ struct VB {
     vbOnExecute   onExecute;   /* CPU instruction execute */
     vbOnFetch     onFetch;     /* CPU instruction fetch */
     vbOnFrame     onFrame;     /* VIP frame ready */
+    vbOnLink      onLink;      /* Communication transfer */
     vbOnRead      onRead;      /* CPU instruction read */
     vbOnSamples   onSamples;   /* VSU samples full */
     vbOnWrite     onWrite;     /* CPU instruction write */
+    VB           *peer;        /* Communication peer */
     void         *tag;         /* User data */
 };
 
@@ -368,6 +461,7 @@ static int32_t SignExtend(int32_t value, int32_t bits) {
 
 /******************************** Sub-Modules ********************************/
 
+#include "ext.c"
 #include "game-pad.c"
 #include "timer.c"
 #include "bus.c"
@@ -391,7 +485,8 @@ static int sysEmulate(VB *sim, uint32_t clocks) {
     ;
 
     /* Process all components */
-    if (!never) ret  = cpuEmulate(sim, clocks);
+    if (!never){ret  = cpuEmulate(sim, clocks);}
+                ret |= extEmulate(sim, clocks);
                        padEmulate(sim, clocks);
                        tmrEmulate(sim, clocks);
                        vsuEmulate(sim, clocks);
@@ -403,6 +498,7 @@ static int sysEmulate(VB *sim, uint32_t clocks) {
 /* Determine how many clocks are guaranteed to process */
 static uint32_t sysUntil(VB *sim, uint32_t clocks) {
     clocks = cpuUntil(sim, clocks);
+    clocks = extUntil(sim, clocks);
     clocks = padUntil(sim, clocks);
     clocks = tmrUntil(sim, clocks);
     clocks = vipUntil(sim, clocks);
@@ -428,19 +524,23 @@ VBAPI int vbEmulate(VB *sim, uint32_t *clocks) {
 }
 
 /* Process multiple simulations */
-VBAPI int vbEmulateEx(VB **sims, int count, uint32_t *clocks) {
+VBAPI int vbEmulateEx(VB **sims, unsigned count, uint32_t *clocks) {
     int      brk;   /* A callback requested a break */
     uint32_t until; /* Clocks guaranteed to process */
-    int      x;     /* Iterator */
+    unsigned x;     /* Iterator */
+
+    /* Process one simulation */
+    if (count == 1)
+        return vbEmulate(sims[0], clocks);
+
+    /* Process multiple simulations */
     while (*clocks != 0) {
         until = *clocks;
-        for (x = count - 1; x >= 0; x--)
+        for (x = count; x > 0; x--)
-            until = sysUntil(sims[x], until);
+            until = sysUntil(sims[x - 1], until);
-
         brk = 0;
-        for (x = count - 1; x >= 0; x--)
+        for (x = count; x > 0; x--)
-            brk |= sysEmulate(sims[x], until);
+            brk |= sysEmulate(sims[x - 1], until);
-
         *clocks -= until;
         if (brk)
             return brk; /* TODO: return 1 */
@@ -487,6 +587,11 @@ VBAPI uint16_t vbGetKeys(VB *sim) {
     return sim->pad.keys;
 }
 
+/* Retrieve the current link callback handler */
+VBAPI vbOnLink vbGetLinkCallback(VB *sim) {
+    return sim->onLink;
+}
+
 /* Retrieve a core option value */
 VBAPI int vbGetOption(VB *sim, int key) {
     switch (key) {
@@ -495,6 +600,11 @@ VBAPI int vbGetOption(VB *sim, int key) {
     return 0;
 }
 
+/* Retrieve the communication peer */
+VBAPI VB* vbGetPeer(VB *sim) {
+    return sim->peer;
+}
+
 /* Retrieve the most recent frame image pixels */
 VBAPI void vbGetPixels(VB *sim, void *left, int leftStrideX, int leftStrideY,
     void *right, int rightStrideX, int rightStrideY) {
@@ -527,7 +637,7 @@ VBAPI void vbGetPixels(VB *sim, void *left, int leftStrideX, int leftStrideY,
             continue;
 
         /* Transfer pixels to the destination */
-        src = sim->vip.output[sim->vip.dp.buffer ^ 1][i];
+        src = sim->vip.output[sim->vip.buffer][i];
         for (y = 0; y < 224; y++, dest += yStride)
         for (x = offset = 0; x < 384; x++, offset += xStride)
             dest[offset] = *src++;
@@ -541,7 +651,7 @@ VBAPI uint32_t vbGetProgramCounter(VB *sim) {
 }
 
 /* Retrieve the value in a program register */
-VBAPI int32_t vbGetProgramRegister(VB *sim, int index) {
+VBAPI int32_t vbGetProgramRegister(VB *sim, unsigned index) {
     return index < 1 || index > 31 ? 0 : sim->cpu.program[index];
 }
 
@@ -551,13 +661,18 @@ VBAPI vbOnRead vbGetReadCallback(VB *sim) {
 }
 
 /* Retrieve the audio samples buffer */
-VBAPI void* vbGetSamples(VB *sim, uint32_t *capacity, uint32_t *position) {
+VBAPI void* vbGetSamples(VB *sim, int *type,
+    unsigned *capacity, unsigned *position) {
     if (sim->vsu.out.samples == NULL) {
+        if (type     != NULL)
+            *type     = 0;
         if (capacity != NULL)
             *capacity = 0;
         if (position != NULL)
             *position = 0;
     } else {
+        if (type     != NULL)
+            *type     = sim->vsu.out.type;
         if (capacity != NULL)
             *capacity = sim->vsu.out.capacity;
         if (position != NULL)
@@ -572,8 +687,8 @@ VBAPI vbOnSamples vbGetSamplesCallback(VB *sim) {
 }
 
 /* Retrieve the value in a system register */
-VBAPI uint32_t vbGetSystemRegister(VB *sim, int index) {
+VBAPI uint32_t vbGetSystemRegister(VB *sim, unsigned index) {
-    return index < 0 || index > 31 ? 0 : cpuGetSystemRegister(sim, index);
+    return index > 31 ? 0 : cpuGetSystemRegister(sim, index);
 }
 
 /* Retrieve a simulation's userdata pointer */
@@ -590,14 +705,17 @@ VBAPI vbOnWrite vbGetWriteCallback(VB *sim) {
 VBAPI VB* vbInit(VB *sim) {
     sim->cart.ram        = NULL;
     sim->cart.rom        = NULL;
+    sim->ph.enabled      = 0;
     sim->vsu.out.samples = NULL;
     sim->onExecute       = NULL;
     sim->onFetch         = NULL;
     sim->onFrame         = NULL;
+    sim->onLink          = NULL;
     sim->onRead          = NULL;
     sim->onSamples       = NULL;
     sim->onWrite         = NULL;
-    sim->ph.enabled      = 0;
+    sim->peer            = NULL;
+    sim->tag             = NULL;
     vbReset(sim);
     return sim;
 }
@@ -616,7 +734,8 @@ VBAPI VB* vbReset(VB *sim) {
     int x; /* Iterator */
 
     /* Wait controller */
-    sim->wcr = 0x00;
+    sim->wcr.exp1w = 0;
+    sim->wcr.rom1w = 0;
 
     /* WRAM (the hardware does not do this) */
     for (x = 0; x < 0x10000; x++)
@@ -624,6 +743,7 @@ VBAPI VB* vbReset(VB *sim) {
 
     /* Components */
     cpuReset(sim);
+    extReset(sim);
     padReset(sim);
     tmrReset(sim);
     vipReset(sim);
@@ -689,6 +809,13 @@ VBAPI uint16_t vbSetKeys(VB *sim, uint16_t keys) {
     return sim->pad.keys = keys;
 }
 
+/* Specify a new link callback handler */
+VBAPI vbOnLink vbSetLinkCallback(VB *sim, vbOnLink callback) {
+    vbOnLink prev = sim->onLink;
+    sim->onLink   = callback;
+    return prev;
+}
+
 /* Specify a new core option value */
 VBAPI int vbSetOption(VB *sim, int key, int value) {
     switch (key) {
@@ -706,8 +833,23 @@ VBAPI int vbSetOption(VB *sim, int key, int value) {
     return value;
 }
 
+/* Specify a new communication peer */
+VBAPI void vbSetPeer(VB *sim, VB *peer) {
+    if (sim->peer == peer)
+        return;
+    if (sim->peer != NULL)
+        sim->peer->peer = NULL;
+    sim->peer = peer;
+    if (peer == NULL)
+        return;
+    if (peer->peer != NULL)
+        peer->peer->peer = NULL;
+    peer->peer = sim;
+}
+
 /* Specify a new value for the program counter */
 VBAPI uint32_t vbSetProgramCounter(VB *sim, uint32_t value) {
+    sim->cpu.clocks    = 0;
     sim->cpu.operation = CPU_FETCH;
     sim->cpu.pc        = sim->cpu.nextPC = value & 0xFFFFFFFE;
     sim->cpu.step      = 0;
@@ -715,7 +857,7 @@ VBAPI uint32_t vbSetProgramCounter(VB *sim, uint32_t value) {
 }
 
 /* Specify a new value for a program register */
-VBAPI int32_t vbSetProgramRegister(VB *sim, int index, int32_t value) {
+VBAPI int32_t vbSetProgramRegister(VB *sim, unsigned index, int32_t value) {
     return index < 1 || index > 31 ? 0 : (sim->cpu.program[index] = value);
 }
 
@@ -727,12 +869,14 @@ VBAPI vbOnRead vbSetReadCallback(VB *sim, vbOnRead callback) {
 }
 
 /* Specify a new audio samples buffer */
-VBAPI int vbSetSamples(VB *sim, void *samples, uint32_t capacity) {
+VBAPI int vbSetSamples(VB *sim, void *samples, int type, unsigned capacity) {
-    if (samples != NULL && (capacity == 0 || capacity > 0x40000000))
+    if (samples != NULL &&
+        (capacity == 0 || (type != VB_S16 && type != VB_F32)))
         return 1;
-    sim->vsu.out.capacity = samples == NULL ? 0 : capacity;
+    sim->vsu.out.capacity = capacity;
     sim->vsu.out.offset   = 0;
     sim->vsu.out.samples  = samples;
+    sim->vsu.out.type     = type;
     return 0;
 }
 
@@ -744,9 +888,8 @@ VBAPI vbOnSamples vbSetSamplesCallback(VB *sim, vbOnSamples callback) {
 }
 
 /* Specify a new value for a system register */
-VBAPI uint32_t vbSetSystemRegister(VB *sim, int index, uint32_t value) {
+VBAPI uint32_t vbSetSystemRegister(VB *sim, unsigned index, uint32_t value) {
-    return index < 0 || index > 31 ? 0 :
+    return index > 31 ? 0 : cpuSetSystemRegister(sim, index, value, 1);
-        cpuSetSystemRegister(sim, index, value, 1);
 }
 
 /* Specify a new write callback handler */
@@ -757,7 +900,7 @@ VBAPI vbOnWrite vbSetWriteCallback(VB *sim, vbOnWrite callback) {
 }
 
 /* Determine the size of a simulation instance */
-VBAPI size_t vbSizeOf() {
+VBAPI size_t vbSizeOf(void) {
     return sizeof (VB);
 }
 

core/vb.h

@@ -22,6 +22,7 @@ extern "C" {
   VB_DIRECT_EXECUTE
   VB_DIRECT_FETCH
   VB_DIRECT_FRAME
+  VB_DIRECT_LINK
   VB_DIRECT_READ
   VB_DIRECT_SAMPLES
   VB_DIRECT_WRITE
@@ -78,10 +79,29 @@ extern "C" {
 #define VB_S16 2
 #define VB_U16 3
 #define VB_S32 4
+#define VB_F32 5
 
 /* Option keys */
 #define VB_PSEUDO_HALT 0
 
+/* Controller buttons */
+#define VB_PWR 0x0001
+#define VB_SGN 0x0002
+#define VB_A   0x0004
+#define VB_B   0x0008
+#define VB_RT  0x0010
+#define VB_LT  0x0020
+#define VB_RU  0x0040
+#define VB_RR  0x0080
+#define VB_LR  0x0100
+#define VB_LL  0x0200
+#define VB_LD  0x0400
+#define VB_LU  0x0800
+#define VB_STA 0x1000
+#define VB_SEL 0x2000
+#define VB_RL  0x4000
+#define VB_RD  0x8000
+
 
 
 /*********************************** Types ***********************************/
@@ -94,6 +114,7 @@ typedef int  (*vbOnException)(VB *sim, uint16_t *cause);
 typedef int  (*vbOnExecute  )(VB *sim, uint32_t address, const uint16_t *code, int length);
 typedef int  (*vbOnFetch    )(VB *sim, int fetch, uint32_t address, int32_t *value, uint32_t *cycles);
 typedef int  (*vbOnFrame    )(VB *sim);
+typedef int  (*vbOnLink     )(VB *sim1, VB *sim2, uint8_t *value1, uint8_t *value2);
 typedef int  (*vbOnRead     )(VB *sim, uint32_t address, int type, int32_t *value, uint32_t *cycles);
 typedef void (*vbOnSamples  )(VB *sim, int16_t *buffer, uint32_t capacity);
 typedef int  (*vbOnWrite    )(VB *sim, uint32_t address, int type, int32_t *value, uint32_t *cycles, int *cancel);
@@ -104,8 +125,7 @@ typedef int  (*vbOnWrite    )(VB *sim, uint32_t address, int type, int32_t *valu
 /******************************* API Commands ********************************/
 
 VBAPI int           vbEmulate             (VB *sim, uint32_t *clocks);
-VBAPI int           vbEmulateEx           (VB **sims, int count, uint32_t *clocks);
+VBAPI int           vbEmulateEx           (VB **sims, unsigned count, uint32_t *clocks);
-VBAPI void*         vbGetCallback         (VB *sim, int id);
 VBAPI void*         vbGetCartRAM          (VB *sim, uint32_t *size);
 VBAPI void*         vbGetCartROM          (VB *sim, uint32_t *size);
 VBAPI vbOnException vbGetExceptionCallback(VB *sim);
@@ -113,14 +133,16 @@ VBAPI vbOnExecute   vbGetExecuteCallback  (VB *sim);
 VBAPI vbOnFetch     vbGetFetchCallback    (VB *sim);
 VBAPI vbOnFrame     vbGetFrameCallback    (VB *sim);
 VBAPI uint16_t      vbGetKeys             (VB *sim);
+VBAPI vbOnLink      vbGetLinkCallback     (VB *sim);
 VBAPI int           vbGetOption           (VB *sim, int key);
+VBAPI VB*           vbGetPeer             (VB *sim);
 VBAPI void          vbGetPixels           (VB *sim, void *left, int leftStrideX, int leftStrideY, void *right, int rightStrideX, int rightStrideY);
 VBAPI uint32_t      vbGetProgramCounter   (VB *sim);
-VBAPI int32_t       vbGetProgramRegister  (VB *sim, int index);
+VBAPI int32_t       vbGetProgramRegister  (VB *sim, unsigned index);
 VBAPI vbOnRead      vbGetReadCallback     (VB *sim);
-VBAPI void*         vbGetSamples          (VB *sim, uint32_t *capacity, uint32_t *position);
+VBAPI void*         vbGetSamples          (VB *sim, int *type, unsigned *capacity, unsigned *position);
 VBAPI vbOnSamples   vbGetSamplesCallback  (VB *sim);
-VBAPI uint32_t      vbGetSystemRegister   (VB *sim, int index);
+VBAPI uint32_t      vbGetSystemRegister   (VB *sim, unsigned index);
 VBAPI void*         vbGetUserData         (VB *sim);
 VBAPI vbOnWrite     vbGetWriteCallback    (VB *sim);
 VBAPI VB*           vbInit                (VB *sim);
@@ -132,17 +154,19 @@ VBAPI vbOnException vbSetExceptionCallback(VB *sim, vbOnException callback);
 VBAPI vbOnExecute   vbSetExecuteCallback  (VB *sim, vbOnExecute callback);
 VBAPI vbOnFetch     vbSetFetchCallback    (VB *sim, vbOnFetch callback);
 VBAPI vbOnFrame     vbSetFrameCallback    (VB *sim, vbOnFrame callback);
+VBAPI vbOnLink      vbSetLinkCallback     (VB *sim, vbOnLink callback);
 VBAPI uint16_t      vbSetKeys             (VB *sim, uint16_t keys);
 VBAPI int           vbSetOption           (VB *sim, int key, int value);
+VBAPI void          vbSetPeer             (VB *sim, VB *peer);
 VBAPI uint32_t      vbSetProgramCounter   (VB *sim, uint32_t value);
-VBAPI int32_t       vbSetProgramRegister  (VB *sim, int index, int32_t value);
+VBAPI int32_t       vbSetProgramRegister  (VB *sim, unsigned index, int32_t value);
 VBAPI vbOnRead      vbSetReadCallback     (VB *sim, vbOnRead callback);
-VBAPI int           vbSetSamples          (VB *sim, void *samples, uint32_t capacity);
+VBAPI int           vbSetSamples          (VB *sim, void *samples, int type, unsigned capacity);
 VBAPI vbOnSamples   vbSetSamplesCallback  (VB *sim, vbOnSamples callback);
-VBAPI uint32_t      vbSetSystemRegister   (VB *sim, int index, uint32_t value);
+VBAPI uint32_t      vbSetSystemRegister   (VB *sim, unsigned index, uint32_t value);
 VBAPI void*         vbSetUserData         (VB *sim, void *tag);
 VBAPI vbOnWrite     vbSetWriteCallback    (VB *sim, vbOnWrite callback);
-VBAPI size_t        vbSizeOf              ();
+VBAPI size_t        vbSizeOf              (void);
 VBAPI int32_t       vbWrite               (VB *sim, uint32_t address, int type, int32_t value);
 
 

core/vsu.c

@@ -45,9 +45,28 @@ static void vsuOnSamples(VB *sim) {
 
 /***************************** Module Functions ******************************/
 
+/* Determine while frequency modifications should be processed */
+static uint8_t vsuCheckFreqMod(VB *sim) {
+    return
+        sim->vsu.freqmod.enb           &&
+        sim->vsu.freqmod.interval != 0 && (
+            sim->vsu.freqmod.modmask != 2 || (
+                sim->vsu.freqmod.func == 1 &&
+                sim->vsu.freqmod.rep
+            )
+        )
+    ;
+}
+
 /* Stage the next frequency modification value */
 static void vsuNextFreqMod(VB *sim, Channel *chan) {
-    uint16_t next;
+    int32_t next;
+
+    /* Modulation mask control */
+    if (sim->vsu.freqmod.modmask == 1 && sim->vsu.freqmod.func == 1) {
+        sim->vsu.freqmod.modmask = 2;
+        chan->freqmod = vsuCheckFreqMod(sim);
+    }
 
     /* Sweep */
     if (sim->vsu.freqmod.func == 0) {
@@ -57,66 +76,37 @@ static void vsuNextFreqMod(VB *sim, Channel *chan) {
         else next = chan->freq.current + next;
         if (next > 2047)
             chan->int_.enb = 0;
+        if (next < 0)
+            next = 0;
     }
 
     /* Modulation */
     else {
-        next = (chan->freq.written +
+        next = ((int32_t) chan->freq.written +
-            sim->vsu.modulation[sim->vsu.freqmod.sample]) & 2047;
+            sim->vsu.modulation[sim->vsu.freqmod.sample]) & 0x7FF;
-        if (sim->vsu.freqmod.sample != 31)
+        if (sim->vsu.freqmod.freqmask == 1)
-            sim->vsu.freqmod.sample++;
+            next = (next & 0x700) | (chan->freq.written & 0x0FF);
-        else if (sim->vsu.freqmod.rep)
+        else if (sim->vsu.freqmod.freqmask == 2)
-            sim->vsu.freqmod.sample = 0;
+            next = (next & 0x0FF) | (chan->freq.written & 0x700);
     }
 
     /* Configure state */
+    if (chan->freqmod)
         sim->vsu.freqmod.next = next;
 }
 
+/* Advance the noise channel's shift register */
+static void vsuNextNoise(VB *sim) {
+    uint32_t bit = ((
+        sim->vsu.noise.register_ >> NOISE_TAPS[sim->vsu.noise.tap] ^
+        sim->vsu.noise.register_ >> 7
+    ) & 1) ^ 1;
+    sim->vsu.noise.register_ = bit |
+        (sim->vsu.noise.register_ << 1 & 0x7FFE);
+}
+
 /* Process one channel */
-static void vsuEmulateChannel(VB *sim, int index, uint32_t clocks) {
+static void vsuEmulateChannel(VB *sim, Channel *chan) {
-    uint32_t bit;     /* Pseudorandom bit */
-    Channel *chan;    /* Channel handle */
-    int      freqmod; /* Frequency modifications enabled */
-    uint32_t until;   /* Clocks to process sub-channel components */
-
-    /* Select channel */
-    chan = &sim->vsu.channels[index];
-
-    /* Channel is disabled */
-    if (!chan->int_.enb)
-        return;
-
-    /* Process all clocks */
-    do {
-
-        /* Frequency modifications are active */
-        freqmod = 
-            index == 4           &&        /* Channel 5 */
-            sim->vsu.freqmod.enb &&        /* Modifications enabled */
-            sim->vsu.freqmod.interval != 0 /* Modifications valid */
-        ;
-
-        /* Clocks until next state change */
-        until = clocks;
-        if (chan->clocks < until)
-            until = chan->clocks;
-        if (chan->env.enb && chan->env.clocks < until)
-            until = chan->env.clocks;
-        if (chan->int_.auto_ && chan->int_.clocks < until)
-            until = chan->int_.clocks;
-        if (freqmod && sim->vsu.freqmod.clocks < until)
-            until = sim->vsu.freqmod.clocks;
-
-        /* Manage clocks */
-        clocks       -= until;
-        chan->clocks -= until;
-        if (chan->env.enb)
-            chan->env.clocks -= until;
-        if (chan->int_.auto_)
-            chan->int_.clocks -= until;
-        if (freqmod)
-            sim->vsu.freqmod.clocks -= until;
 
     /* Automatic shutoff */
     if (chan->int_.auto_ && chan->int_.clocks == 0) {
@@ -124,11 +114,11 @@ static void vsuEmulateChannel(VB *sim, int index, uint32_t clocks) {
         return;
     }
 
-        /* Next sample */
+    /* Next input sample */
     if (chan->clocks == 0) {
 
         /* Wave */
-            if (index != 5) {
+        if (chan != &sim->vsu.channels[5]) {
             chan->clocks =  4 * (2048 - (uint32_t) chan->freq.current);
             chan->wave.sample = (chan->wave.sample + 1) & 31;
         }
@@ -136,38 +126,61 @@ static void vsuEmulateChannel(VB *sim, int index, uint32_t clocks) {
         /* Noise */
         else {
             chan->clocks = 40 * (2048 - (uint32_t) chan->freq.current);
-                bit = ((
+            vsuNextNoise(sim);
-                    sim->vsu.noise.register_ >> NOISE_TAPS[sim->vsu.noise.tap]^
-                    sim->vsu.noise.register_ >> 7
-                ) & 1) ^ 1;
-                sim->vsu.noise.register_ = bit |
-                    (sim->vsu.noise.register_ << 1 & 0x7FFE);
         }
 
     }
 
     /* Envelope modification */
-        if (chan->env.enb && chan->env.clocks == 0) {
+    if (chan->env.clocks == 0) {
+        uint8_t new_envelope = chan->env.value;
         if (chan->env.dir == 0 && chan->env.value != 0)
-                chan->env.value--;
+            new_envelope--;
         else if (chan->env.dir == 1 && chan->env.value != 15)
-                chan->env.value++;
+            new_envelope++;
-            else if (chan->env.rep)
+        else if (chan->env.rep && chan->env.modmask != 2) {
-                chan->env.value = chan->env.reload;
+            new_envelope = chan->env.reload;
+            chan->env.modmask = 0;
+        } else if (!chan->env.modmask)
+            chan->env.modmask = 1;
+        if (chan->env.enb && !chan->env.modmask)
+            chan->env.value = new_envelope;
         chan->env.clocks = ((uint32_t) chan->env.interval + 1) * 307220;
     }
 
     /* Frequency modification */
-        if (freqmod && sim->vsu.freqmod.clocks == 0) {
+    if (chan == &sim->vsu.channels[4] && sim->vsu.freqmod.clocks == 0) {
+
+        /* Apply previously computed frequency modification */
+        if (chan->freqmod)
             chan->freq.current = sim->vsu.freqmod.next;
-            vsuNextFreqMod(sim, chan);
+
+        /* Channel itself is disabled */
         if (!chan->int_.enb)
             return;
+
+        /* Frequency modifications are enabled */
+        if (chan->freqmod) {
+
+            /* Not the final modulation sample */
+            if (sim->vsu.freqmod.sample != 31)
+                sim->vsu.freqmod.sample++;
+
+            /* Last modulation sample processed */
+            else {
+                sim->vsu.freqmod.modmask = 1;
+                if (sim->vsu.freqmod.rep)
+                    sim->vsu.freqmod.sample = 0;
+            }
+
+            /* Schedule next modification */
             sim->vsu.freqmod.clocks = (uint32_t) sim->vsu.freqmod.interval *
                 (sim->vsu.freqmod.clk == 0 ? 19200 : 153600);
         }
 
-    } while (clocks != 0);
+        /* Always process and validate next frequency value */
+        vsuNextFreqMod(sim, chan);
+    }
 
 }
 
@@ -207,8 +220,11 @@ static void vsuWriteEV0(VB *sim, int index, uint8_t value) {
     chan->env.interval = value      &  7;
     chan->env.value    = value >> 4 & 15;
     chan->env.reload   = chan->env.value;
-    if (index == 4)
+    if (chan->env.modmask == 1) chan->env.modmask = 2;
+    if (index == 4) {
+        chan->freqmod = vsuCheckFreqMod(sim);
         vsuNextFreqMod(sim, chan);
+    }
 
     /* Configure state */
     chan->env.clocks = 307220 * ((uint32_t) chan->env.interval + 1);
@@ -221,6 +237,12 @@ static void vsuWriteEV1(VB *sim, int index, uint8_t value) {
     /* Parse fields */
     chan->env.enb = value      & 1;
     chan->env.rep = value >> 1 & 1;
+    if (
+        !chan->env.rep && (
+            (chan->env.reload ==  0 && chan->env.dir == 0) ||
+            (chan->env.reload == 15 && chan->env.dir == 1)
+        )
+    ) chan->env.modmask = 1;
 
     /* Processing by channel */
     switch (index) {
@@ -229,12 +251,14 @@ static void vsuWriteEV1(VB *sim, int index, uint8_t value) {
             sim->vsu.freqmod.enb  = value >> 6 & 1;
             sim->vsu.freqmod.func = value >> 4 & 1;
             sim->vsu.freqmod.rep  = value >> 5 & 1;
+            chan->freqmod         = vsuCheckFreqMod(sim);
             vsuNextFreqMod(sim, chan);
             break;
 
         case 5: /* Channel 6 */
             sim->vsu.noise.tap       = value >> 4 & 7;
             sim->vsu.noise.register_ = 0x0000;
+            vsuNextNoise(sim);
     }
 
 }
@@ -245,7 +269,9 @@ static void vsuWriteFQH(VB *sim, int index, uint16_t value) {
     value = value << 8 & 0x0700;
     chan->freq.current = (chan->freq.current & 0x00FF) | value;
     chan->freq.written = (chan->freq.written & 0x00FF) | value;
-    if (index == 4)
+    if (index != 4)
+        return;
+    sim->vsu.freqmod.freqmask = 2;
     vsuNextFreqMod(sim, chan);
 }
 
@@ -254,7 +280,9 @@ static void vsuWriteFQL(VB *sim, int index, uint8_t value) {
     Channel *chan = &sim->vsu.channels[index];
     chan->freq.current = (chan->freq.current & 0x0700) | value;
     chan->freq.written = (chan->freq.written & 0x0700) | value;
-    if (index == 4)
+    if (index != 4)
+        return;
+    sim->vsu.freqmod.freqmask = 1;
     vsuNextFreqMod(sim, chan);
 }
 
@@ -269,19 +297,29 @@ static void vsuWriteINT(VB *sim, int index, uint8_t value) {
 
     /* Update state */
     chan->int_.clocks = 76805 * ((uint32_t) chan->int_.interval + 1);
-    if (chan->env.enb)
+    chan->env.modmask = 0;
+    if (
+        !chan->env.rep && (
+            (chan->env.reload ==  0 && chan->env.dir == 0) ||
+            (chan->env.reload == 15 && chan->env.dir == 1)
+        )
+    ) chan->env.modmask = 1;
     chan->env.clocks = 307220 * ((uint32_t) chan->env.interval + 1);
     if (index != 5) {
         chan->wave.sample = 0;
         chan->clocks =  4 * (2048 - (uint32_t) chan->freq.current);
     } else {
         sim->vsu.noise.register_ = 0x0000;
+        vsuNextNoise(sim);
         chan->clocks = 40 * (2048 - (uint32_t) chan->freq.current);
     }
     if (index == 4) {
         sim->vsu.freqmod.clocks = (uint32_t) sim->vsu.freqmod.interval *
             (sim->vsu.freqmod.clk == 0 ? 19200 : 153600);
+        sim->vsu.freqmod.modmask = 0;
         sim->vsu.freqmod.sample  = 0;
+        chan->freqmod = vsuCheckFreqMod(sim);
+        vsuNextFreqMod(sim, chan);
     }
 
 }
@@ -313,6 +351,8 @@ static void vsuWriteSWP(VB *sim, uint8_t value) {
         (sim->vsu.freqmod.clk == 0 ? 19200 : 153600);
     if (clocks < sim->vsu.freqmod.clocks)
         sim->vsu.freqmod.clocks = clocks;
+    sim->vsu.channels[4].freqmod = vsuCheckFreqMod(sim);
+    vsuNextFreqMod(sim, &sim->vsu.channels[4]);
 }
 
 
@@ -321,6 +361,8 @@ static void vsuWriteSWP(VB *sim, uint8_t value) {
 
 /* Process component */
 static void vsuEmulate(VB *sim, uint32_t clocks) {
+    Channel *chan;      /* Input channel */
+    uint32_t chantil;   /* Clocks until next channel state update */
     float    i0;        /* Current analog input sample */
     float    o0;        /* Current analog output sample */
     uint16_t output[2]; /* Digital output samples */
@@ -340,12 +382,55 @@ static void vsuEmulate(VB *sim, uint32_t clocks) {
         sim->vsu.clocks -= until;
 
         /* Process all channels */
-        for (x = 0; x < 6; x++)
+        for (x = 0; x < 6; x++) {
-            vsuEmulateChannel(sim, x, until);
+            chan    = &sim->vsu.channels[x];
+            chantil = until;
+
+            /* Process all clocks */
+            while (chan->int_.enb && chantil != 0) {
+
+                /* Determine when the next state change will occur */
+                if (chan->until == 0) {
+
+                    /* Clocks until next state change */
+                    chan->until = chan->clocks;
+                    if (chan->env.enb && chan->env.modmask != 2 &&
+                        chan->env.clocks < chan->until)
+                        chan->until = chan->env.clocks;
+                    if (chan->int_.auto_ && chan->int_.clocks < chan->until)
+                        chan->until = chan->int_.clocks;
+                    if (chan->freqmod && sim->vsu.freqmod.clocks < chan->until)
+                        chan->until = sim->vsu.freqmod.clocks;
+
+                    /* Manage clocks */
+                    chan->clocks -= chan->until;
+                    if (chan->env.enb && chan->env.modmask != 2)
+                        chan->env.clocks -= chan->until;
+                    if (chan->int_.auto_)
+                        chan->int_.clocks -= chan->until;
+                    if (chan->freqmod)
+                        sim->vsu.freqmod.clocks -= chan->until;
+                }
+
+                /* Manage clocks */
+                if (chan->until > chantil) {
+                    chan->until -= chantil;
+                    chantil      = 0;
+                } else {
+                    chantil     -= chan->until;
+                    chan->until  = 0;
+                }
+
+                /* Update channel state */
+                if (chan->until == 0)
+                    vsuEmulateChannel(sim, chan);
+            }
+
+        }
 
         /* Wait for the current sample to finish */
         if (sim->vsu.clocks != 0)
-            continue;
+            return;
 
         /* Compute the output sample */
         output[0] = output[1] = 0;
@@ -368,8 +453,21 @@ static void vsuEmulate(VB *sim, uint32_t clocks) {
                 sim->vsu.out.samples != NULL &&
                 sim->vsu.out.offset >> 1 < sim->vsu.out.capacity
             ) {
-                sim->vsu.out.samples[sim->vsu.out.offset++] =
+
-                    (int16_t) (o0 * 32767.0f + (o0 < 0.0f ? -0.5f : +0.5f));
+                /* Processing by data type */
+                switch (sim->vsu.out.type) {
+                    case VB_S16:
+                        ((int16_t *) sim->vsu.out.samples)
+                        [sim->vsu.out.offset++] = (int16_t)
+                        (o0 * 32767.0f + (o0 < 0.0f ? -0.5f : +0.5f));
+                        break;
+                    case VB_F32:
+                        ((float *) sim->vsu.out.samples)
+                        [sim->vsu.out.offset++] = o0;
+                        break;
+                }
+
+                /* Invoke the samples callback */
                 if (
                     e == 1 &&
                     sim->vsu.out.offset >> 1 == sim->vsu.out.capacity
@@ -403,10 +501,13 @@ static void vsuReset(VB *sim) {
     for (x = 0; x < 6; x++) {
         chan = &sim->vsu.channels[x];
         chan->clocks        = 0;
+        chan->freqmod       = 0;
+        chan->until         = 0;
         chan->env.clocks    = 0;
         chan->env.enb       = 0;
         chan->env.dir       = 0;
         chan->env.interval  = 0;
+        chan->env.modmask   = 0;
         chan->env.reload    = 0;
         chan->env.rep       = 0;
         chan->env.value     = 0;
@@ -427,8 +528,10 @@ static void vsuReset(VB *sim) {
     sim->vsu.freqmod.clocks   = 0;
     sim->vsu.freqmod.dir      = 0;
     sim->vsu.freqmod.enb      = 0;
+    sim->vsu.freqmod.freqmask = 0;
     sim->vsu.freqmod.func     = 0;
     sim->vsu.freqmod.interval = 0;
+    sim->vsu.freqmod.modmask  = 0;
     sim->vsu.freqmod.next     = 0;
     sim->vsu.freqmod.rep      = 0;
     sim->vsu.freqmod.sample   = 0;
@@ -445,21 +548,17 @@ static void vsuReset(VB *sim) {
 
 /* Write a typed value to the VSU bus */
 static void vsuWrite(VB*sim,uint32_t address,int type,int32_t value,int debug){
-
+    (void) type;
-    /* Only byte writes are allowed */
-    switch (type) {
-        case VB_S16:
-        case VB_U16:
-        case VB_S32:
-            return;
-    }
 
     /* Unmapped */
-    if (address & 3)
+    if (address & 1)
         return;
 
     /* Working variables */
-    address &= 0x7FF;
+    address &= 0x7FC;
+
+    /* Clear frequency mask */
+    sim->vsu.freqmod.freqmask = 0;
 
     /* Wave memory */
     if (address < 0x280) {

makefile

@@ -10,6 +10,7 @@ help:
 	@echo "Available make targets:"
 	@echo "  clean   Remove output files"
 	@echo "  core    Check the C core source for compiler warnings"
+	@echo "  util    Check the C utility source for compiler warnings"
 	@echo "  wasm    Build the WebAssembly module"
 	@echo
 
@@ -29,7 +30,7 @@ core:
         -D VB_DIRECT_EXCEPTION=textException -D VB_DIRECT_EXECUTE=textExecute \
         -D VB_DIRECT_FETCH=testFetch -D VB_DIRECT_FRAME=testFrame \
         -D VB_DIRECT_WRITE=testWrite -D VB_DIRECT_SAMPLES=testSamples \
-        -D VB_DIRECT_READ=testRead
+        -D VB_DIRECT_READ=testRead -D VB_DIRECT_LINK=testLink
 #	Clang generic
 	@emcc core/vb.c -I core -c -o /dev/null -O3 \
         -Werror -std=c90 -Wall -Wextra -Wpedantic -fno-strict-aliasing
@@ -40,14 +41,32 @@ core:
         -D VB_DIRECT_EXCEPTION=textException -D VB_DIRECT_EXECUTE=textExecute \
         -D VB_DIRECT_FETCH=testFetch -D VB_DIRECT_FRAME=testFrame \
         -D VB_DIRECT_WRITE=testWrite -D VB_DIRECT_SAMPLES=testSamples \
-        -D VB_DIRECT_READ=testRead
+        -D VB_DIRECT_READ=testRead -D VB_DIRECT_LINK=testLink
+
+.PHONY: util
+util:
+#	GCC generic
+	@gcc util/vbu.c -I core -I util -c -o /dev/null -O3 \
+        -Werror -std=c90 -Wall -Wextra -Wpedantic -fno-strict-aliasing
+#	GCC compilation control
+	@gcc util/vbu.c -I core -I util -c -o /dev/null -O3 \
+        -Werror -std=c90 -Wall -Wextra -Wpedantic -fno-strict-aliasing \
+        -D VB_SIGNED_PROPAGATE -D VBU_REALLOC=testRealloc
+#	Clang generic
+	@emcc util/vbu.c -I core -I util -c -o /dev/null -O3 \
+        -Werror -std=c90 -Wall -Wextra -Wpedantic -fno-strict-aliasing
+#	Clang compilation control
+	@emcc util/vbu.c -I core -I util -c -o /dev/null -O3 \
+        -Werror -std=c90 -Wall -Wextra -Wpedantic -fno-strict-aliasing \
+        -D VB_SIGNED_PROPAGATE -D VBU_REALLOC=testRealloc
 
 .PHONY: wasm
 wasm:
-	@emcc -o web/core.wasm web/wasm.c core/vb.c -I core \
+	@emcc -o web/core.wasm web/wasm.c core/vb.c util/vbu.c -I core -I util \
         -D VB_LITTLE_ENDIAN -D VB_SIGNED_PROPAGATE \
-        -D "VBAPI=__attribute__((used))" \
+        -D "VBAPI=__attribute__((used))" -D "VBUAPI=__attribute__((used))" \
-        --no-entry -O2 -flto -s WASM=1 -s WARN_ON_UNDEFINED_SYMBOLS=0 \
+        -D VB_DIRECT_FRAME=wasmOnFrame \
+        --no-entry -O2 -flto -s WASM=1 \
         -s EXPORTED_RUNTIME_METHODS=[] -s ALLOW_MEMORY_GROWTH \
         -s MAXIMUM_MEMORY=4GB -fno-strict-aliasing
 	@rm -f web/*.wasm.tmp*

util/disassembler.c

@@ -0,0 +1,700 @@
+/* This file is included into vbu.c and cannot be compiled on its own. */
+#ifdef VBUAPI
+
+
+
+/********************************* Constants *********************************/
+
+/* Operand types */
+#define DASM_BCOND   0
+#define DASM_DISP9   1
+#define DASM_DISP26  2
+#define DASM_IMM5S   3
+#define DASM_IMM5U   4
+#define DASM_IMM16S  5
+#define DASM_IMM16U  6
+#define DASM_JMP     7
+#define DASM_MEMORY  8
+#define DASM_REG1    9
+#define DASM_REG2   10
+#define DASM_SETF   11
+#define DASM_SYSTEM 12
+
+
+
+/******************************** Lookup Data ********************************/
+
+/* Instruction descriptor */
+typedef struct {
+    char    mnemonic[8];    /* Mnemonic, uppercase */
+    uint8_t operandsLength; /* Number of operands */
+    uint8_t operands[3];    /* Operand types */
+} OpDef;
+
+/* Instruction descriptors */
+static const OpDef OPDEFS[] = {
+    { "MOV"  , 2, { DASM_REG1, DASM_REG2 } },   /* 000000 */
+    { "ADD"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "SUB"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "CMP"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "SHL"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "SHR"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "JMP"  , 1, { DASM_JMP } },
+    { "SAR"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "MUL"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "DIV"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "MULU" , 2, { DASM_REG1, DASM_REG2 } },
+    { "DIVU" , 2, { DASM_REG1, DASM_REG2 } },
+    { "OR"   , 2, { DASM_REG1, DASM_REG2 } },
+    { "AND"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "XOR"  , 2, { DASM_REG1, DASM_REG2 } },
+    { "NOT"  , 1, { DASM_REG1 } },
+
+    { "MOV"  , 2, { DASM_IMM5S, DASM_REG2 } },  /* 010000 */
+    { "ADD"  , 2, { DASM_IMM5S, DASM_REG2 } },
+    { ""     , 0, { 0 } }, /* SETF */
+    { "CMP"  , 2, { DASM_IMM5S, DASM_REG2 } },
+    { "SHL"  , 2, { DASM_IMM5U, DASM_REG2 } },
+    { "SHR"  , 2, { DASM_IMM5U, DASM_REG2 } },
+    { "CLI"  , 0, { 0 } },
+    { "SAR"  , 2, { DASM_IMM5U, DASM_REG2 } },
+    { "TRAP" , 1, { DASM_IMM5U } },
+    { "RETI" , 0, { 0 } },
+    { "HALT" , 0, { 0 } },
+    { "---"  , 0, { 0 } },
+    { "LDSR" , 2, { DASM_REG2, DASM_SYSTEM } },
+    { "STSR" , 2, { DASM_SYSTEM, DASM_REG2 } },
+    { "SEI"  , 0, { 0 } },
+    { ""     , 0, { 0 } }, /* Bit string */
+
+    { ""     , 0, { 0 } }, /* BCOND */          /* 100000 */
+    { ""     , 0, { 0 } }, /* BCOND */
+    { ""     , 0, { 0 } }, /* BCOND */
+    { ""     , 0, { 0 } }, /* BCOND */
+    { ""     , 0, { 0 } }, /* BCOND */
+    { ""     , 0, { 0 } }, /* BCOND */
+    { ""     , 0, { 0 } }, /* BCOND */
+    { ""     , 0, { 0 } }, /* BCOND */
+    { "MOVEA", 3, { DASM_IMM16U, DASM_REG1, DASM_REG2 } },
+    { "ADDI" , 3, { DASM_IMM16S, DASM_REG1, DASM_REG2 } },
+    { "JR"   , 1, { DASM_DISP26 } },
+    { "JAL"  , 1, { DASM_DISP26 } },
+    { "ORI"  , 3, { DASM_IMM16U, DASM_REG1, DASM_REG2 } },
+    { "ANDI" , 3, { DASM_IMM16U, DASM_REG1, DASM_REG2 } },
+    { "XORI" , 3, { DASM_IMM16U, DASM_REG1, DASM_REG2 } },
+    { "MOVHI", 3, { DASM_IMM16U, DASM_REG1, DASM_REG2 } },
+
+    { "LD.B" , 2, { DASM_MEMORY, DASM_REG2 } }, /* 110000 */
+    { "LD.H" , 2, { DASM_MEMORY, DASM_REG2 } },
+    { "---"  , 0, { 0 } },
+    { "LD.W" , 2, { DASM_MEMORY, DASM_REG2 } },
+    { "ST.B" , 2, { DASM_REG2, DASM_MEMORY } },
+    { "ST.H" , 2, { DASM_REG2, DASM_MEMORY } },
+    { "---"  , 0, { 0 } },
+    { "ST.W" , 2, { DASM_REG2, DASM_MEMORY } },
+    { "IN.B" , 2, { DASM_MEMORY, DASM_REG2 } },
+    { "IN.H" , 2, { DASM_MEMORY, DASM_REG2 } },
+    { "CAXI" , 0, { DASM_MEMORY, DASM_REG2 } },
+    { "IN.W" , 2, { DASM_MEMORY, DASM_REG2 } },
+    { "OUT.B", 2, { DASM_REG2, DASM_MEMORY } },
+    { "OUT.H", 2, { DASM_REG2, DASM_MEMORY } },
+    { ""     , 0, { 0 } }, /* Floating-point/Nintendo */
+    { "OUT.W", 2, { DASM_REG2, DASM_MEMORY } }
+};
+
+/* Bit string instruction descriptors */
+static const OpDef OPDEFS_BITSTRING[] = {
+    { "SCH0BSU", 0, { 0 } }, /* 00000 */
+    { "SCH0BSD", 0, { 0 } },
+    { "SCH1BSU", 0, { 0 } },
+    { "SCH1BSD", 0, { 0 } },
+    { "---"    , 0, { 0 } },
+    { "---"    , 0, { 0 } },
+    { "---"    , 0, { 0 } },
+    { "---"    , 0, { 0 } },
+    { "ORBSU"  , 0, { 0 } },
+    { "ANDBSU" , 0, { 0 } },
+    { "XORBSU" , 0, { 0 } },
+    { "MOVBSU" , 0, { 0 } },
+    { "ORNBSU" , 0, { 0 } },
+    { "ANDNBSU", 0, { 0 } },
+    { "XORNBSU", 0, { 0 } },
+    { "NOTBSU" , 0, { 0 } }
+    /* +16 invalid opcodes */
+};
+
+/* Floating-point/Nintendo instruction descriptors */
+static const OpDef OPDEFS_FLOATENDO[] = {
+    { "CMPF.S" , 2, { DASM_REG1, DASM_REG2 } },
+    { "---"    , 0, { 0 } },
+    { "CVT.WS" , 2, { DASM_REG1, DASM_REG2 } },
+    { "CVT.SW" , 2, { DASM_REG1, DASM_REG2 } },
+    { "ADDF.S" , 2, { DASM_REG1, DASM_REG2 } },
+    { "SUBF.S" , 2, { DASM_REG1, DASM_REG2 } },
+    { "MULF.S" , 2, { DASM_REG1, DASM_REG2 } },
+    { "DIVF.S" , 2, { DASM_REG1, DASM_REG2 } },
+    { "XB"     , 1, { DASM_REG2 } },
+    { "XH"     , 1, { DASM_REG2 } },
+    { "REV"    , 2, { DASM_REG1, DASM_REG2 } },
+    { "TRNC.SW", 2, { DASM_REG1, DASM_REG2 } },
+    { "MPYHW"  , 2, { DASM_REG1, DASM_REG2 } },
+    /* +51 invalid opcodes */
+};
+
+/* Invalid instruction descriptors */
+static const OpDef OPDEF_ILLEGAL = { "---", 0, { 0 } };
+
+
+
+/***************************** Module Functions ******************************/
+
+/* Select the display text for a condition */
+static char* dasmCondition(VBU_DasmConfig *config, int cond) {
+    switch (cond) {
+        case  0: return "V" ;
+        case  1: return config->conditionCL == VBU_C ? "C" : "L";
+        case  2: return config->conditionEZ == VBU_E ? "E" : "Z";
+        case  3: return "NH";
+        case  4: return "N" ;
+        case  5: return "T" ;
+        case  6: return "LT";
+        case  7: return "LE";
+        case  8: return "NV";
+        case  9: return config->conditionCL == VBU_C ? "NC" : "NL";
+        case 10: return config->conditionEZ == VBU_E ? "NE" : "NZ";
+        case 11: return "H" ;
+        case 12: return "P" ;
+        case 13: return "F" ;
+        case 14: return "GE";
+    }
+    return "GT";
+}
+
+/* Format a number as hexadecimal */
+static void dasmToHex(char *dest, VBU_DasmConfig *config,
+    int minDigits, int32_t value) {
+    char  format[9];
+    char *prefix = "";
+    char *suffix = "";
+    switch (config->hexNotation) {
+        case VBU_0X    : prefix = "0x"; break;
+        case VBU_DOLLAR: prefix = "$" ; break;
+        case VBU_H     : suffix = "h" ; break;
+    }
+    sprintf(format, "%%s%%0%d%s%%s", minDigits,
+        config->hexCase == VBU_LOWER ? "x" : "X");
+    sprintf(dest, format, prefix, value, suffix);
+    if (config->hexNotation != VBU_H || *dest <= '9')
+        return;
+    *dest++ = '0';
+    sprintf(dest, format, prefix, value, suffix);
+}
+
+/* Convert a string to lowercase */
+static void dasmToLower(char *str) {
+    for (; *str; str++) {
+        if (*str >= 'A' && *str <= 'Z')
+            *str += 'a' - 'A';
+    }
+}
+
+/* Format a program register */
+static void dasmProgram(char *dest, VBU_DasmConfig *config, int id) {
+    char *text = NULL;
+    if (config->programNotation != VBU_NUMBERS) {
+        switch (id) {
+            case  2: text = "HP"; break;
+            case  3: text = "SP"; break;
+            case  4: text = "GP"; break;
+            case  5: text = "TP"; break;
+            case 31: text = "LP"; break;
+        }
+    }
+    if (text == NULL)
+        sprintf(dest, "R%d", id);
+    else strcpy(dest, text);
+    if (config->programCase == VBU_LOWER)
+        dasmToLower(dest);
+}
+
+
+
+/**************************** Operand Formatters *****************************/
+
+/* Format the condition operand of a split BCOND instruction */
+static void dasmOpBCOND(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    int cond = line->code[1] >> 2 & 15;
+    if (config->conditionNotation == VBU_NUMBERS)
+        sprintf(dest, "%d", cond);
+    else {
+        strcpy(dest, dasmCondition(config, cond));
+        if (config->conditionCase == VBU_LOWER)
+            dasmToLower(dest);
+    }
+}
+
+/* Format a 9-bit displacement operand */
+static void dasmOpDisp9(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    int32_t disp = SignExtend((int32_t) line->code[1] << 8 | line->code[0], 9);
+    sprintf(dest, config->hexCase == VBU_LOWER ?
+        "%08x" : "%08X", line->address + disp);
+}
+
+/* Format a 26-bit displacement operand */
+static void dasmOpDisp26(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    int32_t disp = SignExtend(
+        (int32_t) line->code[1] << 24 |
+        (int32_t) line->code[0] << 16 |
+        (int32_t) line->code[3] <<  8 |
+                  line->code[2]
+    , 26);
+    sprintf(dest, config->hexCase == VBU_LOWER ?
+        "%08x" : "%08X", line->address + disp);
+}
+
+/* Format a 5-bit sign-extended immediate operand */
+static void dasmOpImm5S(char *dest, VBU_DasmConfig*config, VBU_DasmLine *line){
+    if (config->immediateNotation == VBU_NUMBER)
+        *dest++ = '#';
+    sprintf(dest, "%d", SignExtend(line->code[0], 5));
+}
+
+/* Format a 5-bit zero-filled immediate operand */
+static void dasmOpImm5U(char *dest, VBU_DasmConfig*config, VBU_DasmLine *line){
+    if (config->immediateNotation == VBU_NUMBER)
+        *dest++ = '#';
+    sprintf(dest, "%d", line->code[0] & 31);
+}
+
+/* Format a 16-bit sign-extended immediate operand */
+static void dasmOpImm16S(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    int32_t imm    = (int16_t) ((int16_t) line->code[3] << 8 | line->code[2]);
+    if (config->immediateNotation == VBU_NUMBER)
+        *dest++ = '#';
+    if (imm >= -256 && imm <= 256) {
+        sprintf(dest, "%d", imm);
+        return;
+    }
+    if (imm < 0) {
+        *dest++ = '-';
+        imm     = -imm;
+    }
+    dasmToHex(dest, config, 0, imm);
+}
+
+/* Format a 16-bit zero-filled immediate operand */
+static void dasmOpImm16U(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    uint16_t imm = (uint16_t) line->code[3] << 8 | line->code[2];
+    if (config->immediateNotation == VBU_NUMBER)
+        *dest++ = '#';
+    dasmToHex(dest, config, 4, imm);
+}
+
+/* Format the operand of a JMP instruction */
+static void dasmOpJMP(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    *dest++ = '[';
+    dasmProgram(dest, config, line->code[0] & 31);
+    strcat(dest, "]");
+}
+
+/* Format a memory operand */
+static void dasmOpMemory(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    int     reg1 = line->code[0] & 31;
+    int32_t disp = (int16_t) ((int16_t) line->code[3] << 8 | line->code[2]);
+
+    /* Displacement of zero */
+    if (disp == 0) {
+        *dest++ = '[';
+        dasmProgram(dest, config, reg1);
+        strcat(dest, "]");
+        return;
+    }
+
+    /* Inside */
+    if (config->memoryNotation == VBU_INSIDE) {
+        *dest++ = '[';
+        dasmProgram(dest, config, reg1);
+        dest += strlen(dest);
+        if (disp < 0) {
+            strcpy(dest, " - ");
+            disp = -disp;
+        } else strcpy(dest, " + ");
+        dest += 3;
+        if (disp <= 256)
+            sprintf(dest, "%d", disp);
+        else dasmToHex(dest, config, 0, disp);
+        strcat(dest, "]");
+    }
+
+    /* Outside */
+    else {
+        if (disp < 0) {
+            *dest++ = '-';
+            disp = -disp;
+        }
+        if (disp <= 256)
+            sprintf(dest, "%d", disp);
+        else dasmToHex(dest, config, 0, disp);
+        dest += strlen(dest);
+        *dest++ = '[';
+        dasmProgram(dest, config, reg1);
+        strcat(dest, "]");
+    }
+
+}
+
+/* Format a source register operand */
+static void dasmOpReg1(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    dasmProgram(dest, config, line->code[0] & 31);
+}
+
+/* Format a destination register operand */
+static void dasmOpReg2(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    dasmProgram(dest, config,
+        ((uint16_t) line->code[1] << 8 | line->code[0]) >> 5 & 31);
+}
+
+/* Format the condition operand of a split SETF instruction */
+static void dasmOpSETF(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    int cond = line->code[0] & 15;
+    if (config->conditionNotation == VBU_NUMBERS)
+        sprintf(dest, "%d", cond);
+    else {
+        strcpy(dest, dasmCondition(config, cond));
+        if (config->conditionCase == VBU_LOWER)
+            dasmToLower(dest);
+    }
+}
+
+/* Format a system register operand */
+static void dasmOpSystem(char*dest, VBU_DasmConfig*config, VBU_DasmLine*line) {
+    int   id   = line->code[0] & 31;
+    char *text = NULL;
+    if (config->systemNotation != VBU_NUMBERS) {
+        switch (id) {
+            case  0: text = "EIPC" ; break;
+            case  1: text = "EIPSW"; break;
+            case  2: text = "FEPC" ; break;
+            case  3: text = "FEPSW"; break;
+            case  4: text = "ECR"  ; break;
+            case  5: text = "PSW"  ; break;
+            case  6: text = "PIR"  ; break;
+            case  7: text = "TKCW" ; break;
+            case 24: text = "CHCW" ; break;
+            case 25: text = "ADTRE"; break;
+        }
+    }
+    if (text == NULL) {
+        sprintf(dest, "%d", id);
+        return;
+    }
+    strcpy(dest, text);
+    if (config->systemCase == VBU_LOWER)
+        dasmToLower(dest);
+}
+
+
+
+/***************************** Module Functions ******************************/
+
+/* Prepare an OpDef for a BCOND instruction */
+static OpDef* dasmBCOND(VBU_DasmConfig *config,
+    VBU_DasmLine *line, OpDef *opdef) {
+    int   cond; /* Condition code */
+    char *text; /* Mnemonic text */
+
+    /* Split notation */
+    if (config->bcondNotation == VBU_SPLIT) {
+        strcpy(opdef->mnemonic, "BCOND");
+        opdef->operandsLength = 2;
+        opdef->operands[0] = DASM_BCOND;
+        opdef->operands[1] = DASM_DISP9;
+        return opdef;
+    }
+
+    /* Joined notation */
+    cond = line->code[1] >> 1 & 15;
+    switch (cond) {
+        case  0: text = "BV" ; break;
+        case  1: text = config->conditionCL == VBU_C ? "BC" : "BL"; break;
+        case  2: text = config->conditionEZ == VBU_E ? "BE" : "BZ"; break;
+        case  3: text = "BNH"; break;
+        case  4: text = "BN" ; break;
+        case  5: text = "BR" ; break;
+        case  6: text = "BLT"; break;
+        case  7: text = "BLE"; break;
+        case  8: text = "BNV"; break;
+        case  9: text = config->conditionCL == VBU_C ? "BNC" : "BNL"; break;
+        case 10: text = config->conditionEZ == VBU_E ? "BNE" : "BNZ"; break;
+        case 11: text = "BH" ; break;
+        case 12: text = "BP" ; break;
+        case 13: text = "NOP"; break;
+        case 14: text = "BGE"; break;
+        default: text = "BGT";
+    }
+    strcpy(opdef->mnemonic, text);
+    opdef->operandsLength = cond != 13;
+    opdef->operands[0]   = DASM_DISP9;
+    return opdef;
+}
+
+/* Ensure an output buffer matches the required size */
+static VBU_DasmLine* dasmGrow(
+    VBU_DasmLine **lines, size_t *size, size_t target, unsigned index) {
+    if (*size < target) {
+        while (*size < target)
+            *size *= 2;
+        *lines = VBU_REALLOC(*lines, *size);
+    }
+    return *lines == NULL ? NULL : &(*lines)[index];
+}
+
+/* Format an operand */
+static void dasmOperand(char *dest, VBU_DasmConfig *config,
+    VBU_DasmLine *line, uint8_t type) {
+    switch (type) {
+        case DASM_BCOND : dasmOpBCOND (dest, config, line); break;
+        case DASM_DISP9 : dasmOpDisp9 (dest, config, line); break;
+        case DASM_DISP26: dasmOpDisp26(dest, config, line); break;
+        case DASM_IMM5S : dasmOpImm5S (dest, config, line); break;
+        case DASM_IMM5U : dasmOpImm5U (dest, config, line); break;
+        case DASM_IMM16S: dasmOpImm16S(dest, config, line); break;
+        case DASM_IMM16U: dasmOpImm16U(dest, config, line); break;
+        case DASM_JMP   : dasmOpJMP   (dest, config, line); break;
+        case DASM_MEMORY: dasmOpMemory(dest, config, line); break;
+        case DASM_REG1  : dasmOpReg1  (dest, config, line); break;
+        case DASM_REG2  : dasmOpReg2  (dest, config, line); break;
+        case DASM_SETF  : dasmOpSETF  (dest, config, line); break;
+        case DASM_SYSTEM: dasmOpSystem(dest, config, line); break;
+    }
+}
+
+/* Prepare an OpDef for a SETF instruction */
+static OpDef* dasmSETF(VBU_DasmConfig *config,
+    VBU_DasmLine *line, OpDef *opdef) {
+
+    /* Split notation */
+    if (config->bcondNotation == VBU_SPLIT) {
+        strcpy(opdef->mnemonic, "SETF");
+        opdef->operandsLength = 2;
+        opdef->operands[0] = DASM_SETF;
+        opdef->operands[1] = DASM_REG2;
+        return opdef;
+    }
+
+    /* Joined notation */
+    sprintf(opdef->mnemonic, "SETF%s",
+        dasmCondition(config, line->code[1] >> 1 & 15));
+    opdef->operandsLength = 1;
+    opdef->operands[0]   = DASM_REG2;
+    return opdef;
+}
+
+/* Disassemble one instruction */
+static int dasmLine(VB *sim, uint32_t *address, uint32_t pc,
+    VBU_DasmConfig *config, VBU_DasmLine **lines, size_t *size, size_t *offset,
+    unsigned index) {
+    char         *dest;             /* Text output pointer */
+    char         *format;           /* Hexadecimal format string */
+    VBU_DasmLine *line;             /* Output line */
+    size_t        more;             /* Number of bytes to output */
+    OpDef        *opdef;            /* Instruction descriptor */
+    OpDef         special;          /* Special-case descriptor */
+    char          tAddress[9];      /* Address display text */
+    char          tCode[4][3];      /* Code display text */
+    char          tMnemonic[8];     /* Mnemonic display text */
+    char          tOperands[3][15]; /* Operands display text */
+    uint32_t      x;                /* Scratch and iterator */
+
+    /* Process non-text members */
+    line = &(*lines)[index];
+    line->address    = *address;
+    line->codeLength = vbuCodeSize(sim, *address);
+    line->isPC       = *address == pc;
+    for (x = 0; x < line->codeLength; x++)
+        line->code[x] = vbRead(sim, *address + x, VB_U8);
+
+    /* Advance to the next instruction or PC, whichever is sooner */
+    *address += pc != *address && pc - *address < line->codeLength ?
+        pc - *address : line->codeLength;
+
+    /* Do not process text members */
+    if (config == NULL) {
+        line->text.address        = NULL;
+        line->text.mnemonic       = NULL;
+        line->text.operandsLength = 0;
+        for (x = 0; x < line->codeLength; x++)
+            line->text.code[x] = NULL;
+        return 0;
+    }
+
+    /* Select instruction descriptor */
+    x = line->code[1] >> 2 & 63;
+    switch (x) {
+        case 0x12: /* SETF */
+            opdef = dasmSETF(config, line, &special);
+            break;
+        case 0x1F: /* Bit string */
+            x     = line->code[0] & 31;
+            opdef = (OpDef *) (x < 16 ? &OPDEFS_BITSTRING[x] : &OPDEF_ILLEGAL);
+            break;
+        case 0x20: case 0x21: case 0x22: case 0x23: /* BCOND */
+        case 0x24: case 0x25: case 0x26: case 0x27:
+            opdef = dasmBCOND(config, line, &special);
+            break;
+        case 0x3E: /* Floating-point/Nintendo */
+            x = line->code[3] >> 2 & 63;
+            opdef = (OpDef *) (x < 13 ? &OPDEFS_FLOATENDO[x] : &OPDEF_ILLEGAL);
+            break;
+        default: opdef = (OpDef *) &OPDEFS[x]; /* Other */
+    }
+
+    /* Address */
+    format = config->hexCase == VBU_LOWER ? "%08x" : "%08X";
+    sprintf(tAddress, format, line->address);
+    more = 9;
+
+    /* Code */
+    format = config->hexCase == VBU_LOWER ? "%02x" : "%02X";
+    for (x = 0; x < line->codeLength; x++) {
+        sprintf(tCode[x], format, (int) line->code[x]);
+        more += 3;
+    }
+
+    /* Mnemonic */
+    strcpy(tMnemonic, opdef->mnemonic);
+    if (config->mnemonicCase == VBU_LOWER)
+        dasmToLower(tMnemonic);
+    more += strlen(tMnemonic) + 1;
+
+    /* Operands */
+    line->text.operandsLength = opdef->operandsLength;
+    for (x = 0; x < opdef->operandsLength; x++) {
+        dasmOperand(tOperands[x], config, line, opdef->operands[x]);
+        more += strlen(tOperands[x]) + 1;
+    }
+
+    /* Grow the text buffer */
+    line = dasmGrow(lines, size, *offset + more, index);
+    if (line == NULL)
+        return 1;
+
+    /* Working variables */
+    dest     = &((char *) *lines)[*offset];
+    *offset += more;
+
+    /* Address */
+    strcpy(dest, tAddress);
+    line->text.address = dest;
+    dest += 9;
+
+    /* Code */
+    for (x = 0; x < line->codeLength; x++) {
+        strcpy(dest, tCode[x]);
+        line->text.code[x] = dest;
+        dest += 3;
+    }
+
+    /* Mnemonic */
+    strcpy(dest, tMnemonic);
+    line->text.mnemonic = dest;
+    dest += strlen(dest) + 1;
+
+    /* Operands */
+    for (x = 0; x < opdef->operandsLength; x++) {
+        strcpy(dest, tOperands[
+            config->operandOrder == VBU_DEST_FIRST ?
+            opdef->operandsLength - 1 - x :
+            x
+        ]);
+        line->text.operands[x] = dest;
+        dest += strlen(dest) + 1;
+    }
+
+    return 0;
+}
+
+
+
+/***************************** Library Functions *****************************/
+
+/* Disassemble from a simulation */
+static VBU_DasmLine* dasmDisassemble(VB *sim, uint32_t address,
+    VBU_DasmConfig *config, unsigned length, int line) {
+    uint32_t      addr;          /* Working address */
+    uint32_t     *circle = NULL; /* Circular address buffer */
+    VBU_DasmLine *lines  = NULL; /* Output line buffer */
+    size_t        offset;        /* Offset into lines buffer */
+    uint32_t      pc;            /* Program counter */
+    size_t        size;          /* Number of bytes in lines */
+    unsigned      x;             /* Iterator */
+
+    /* Nothing to disassemble */
+    if (length == 0)
+        return NULL;
+
+    /* Establish a circular buffer */
+    if (line > 0) {
+        circle = VBU_REALLOC(NULL, (size_t) (line + 1) * sizeof (uint32_t));
+        if (circle == NULL)
+            goto catch;
+    }
+
+    /* Begin decoding from at least 10 lines before first/reference */
+    addr = (address & 0xFFFFFFFE) -
+        (int32_t) (line <= 0 ? 10 : line + 10) * 4;
+
+    /* Locate the address of the line containing the reference address */
+    pc = vbGetProgramCounter(sim);
+    for (x = 0;;) {
+
+        /* Track the address in the circular buffer */
+        if (line > 0) {
+            circle[x] = addr;
+            if (++x > (size_t) line)
+                x = 0;
+        }
+
+        /* Check if the instruction contains the reference address */
+        size = vbuCodeSize(sim, addr);
+        if (address - addr < size)
+            break;
+
+        /* Advance to the next instruction or PC, whichever is sooner */
+        addr += addr != pc && pc - addr < size ? pc - addr : size;
+    }
+
+    /* Address of first line is in the circular buffer */
+    if (line > 0) {
+        addr   = circle[x];
+        circle = VBU_REALLOC(circle, 0);
+    }
+
+    /* Keep decoding until the first line of output */
+    else for (; line < 0; line++)
+        addr += vbuCodeSize(sim, addr);
+
+    /* Working variables */
+    size   = length * sizeof (VBU_DasmLine);
+    lines  = VBU_REALLOC(NULL, size);
+    offset = size;
+    if (lines == NULL)
+        goto catch;
+
+    /* Process output lines */
+    for (x = 0; x < length; x++) {
+        if (dasmLine(sim, &addr, pc, config, &lines, &size, &offset, x))
+            goto catch;
+    }
+    return VBU_REALLOC(lines, offset);
+
+    /* Exception handler */
+    catch:
+    circle = VBU_REALLOC(circle, 0);
+    lines  = VBU_REALLOC(lines , 0);
+    return NULL;
+}
+
+
+
+#endif /* VBUAPI */

util/isx.c

@@ -0,0 +1,297 @@
+/* This file is included into vbu.c and cannot be compiled on its own. */
+#ifdef VBUAPI
+
+
+
+/********************************* Constants *********************************/
+
+/* Range types */
+/*
+0x41 ('A')   8-bit integer (.db), string
+0x42 ('B')   8-bit integer (.db), numeric
+0x43 ('C')   Compiled C code
+0x44 ('D')   16-bit integer (.dd, high byte first)
+0x45 ('E')   65C816 code (8-bit accumulator, 8-bit index)
+0x46 ('F')   65C816 code (8-bit accumulator, 16-bit index)
+0x47 ('G')   65C816 code (16-bit accumulator, 8-bit index)
+0x48 ('H')   65C816 code (16-bit accumulator, 16-bit index)
+0x4C ('L')   32-bit integer (.dl SNES, .dw Virtual Boy, low byte first)
+0x53 ('S')   Size reservation, as in .bss allocation (.ds)
+0x57 ('W')   16-bit integer (.dw SNES, .dh Virtual Boy, low byte first)
+*/
+
+
+
+/***************************** Module Functions ******************************/
+
+/* Skip ISX record type 0x01 */
+static size_t isx01(uint8_t *bytes, size_t length, size_t src) {
+    /*
+      u8   Type         =0x01
+      u8   Bank         Cartridge bank number
+      u8   BankHigh     Only if Bank >= 0x80
+      u16  Address      CPU bus address
+      u16  DataLength   Number of bytes in Data
+      u8[] Data         Code bytes
+    */
+
+    /* Bank field is not present */
+    if (src + 2 > length)
+        return (size_t) -1;
+
+    /* Advance to DataLength field */
+    src += bytes[src + 1] >= 0x80 ? 5 : 4;
+
+    /* DataLength field is not present */
+    if (src + 2 > length)
+        return (size_t) -1;
+
+    /* Advance past Data field */
+    return src + 2 + ((uint16_t) bytes[src + 1] << 8 | bytes[src]);
+}
+
+/* Decode ISX record type 0x11 */
+static size_t isx11(uint8_t *bytes, size_t length, size_t src,
+    uint32_t *address, uint32_t *size) {
+    /*
+      u8   Type         =0x11
+      u32  Address      CPU bus address
+      u32  DataLength   Number of bytes in Data
+      u8[] Data         Code bytes
+    */
+
+    /* DataLength field is not present */
+    if (src + 9 > length)
+        return (size_t) -1;
+
+    /* Parse Address and DataLength fields */
+    *address = (uint32_t) bytes[src+4] << 24 | (uint32_t) bytes[src+3] << 16 |
+               (uint32_t) bytes[src+2] <<  8 |            bytes[src+1];
+    *size    = (uint32_t) bytes[src+8] << 24 | (uint32_t) bytes[src+7] << 16 |
+               (uint32_t) bytes[src+6] <<  8 |            bytes[src+5];
+
+    /* Advance past Data field */
+    return src + 9 + *size;
+}
+
+/* Skip ISX range records */
+static size_t isxRange(uint8_t *bytes,size_t length,size_t src,size_t size) {
+    /*
+      u8      Type            =0x03 (SNES) or 0x13 (Virtual Boy)
+      u16     Count           Number of ranges
+      Range[] Ranges
+       === SNES fields ===
+       u8      Bank           Cartridge bank number
+       u16     StartAddress   Lowest CPU bus address
+       u16     EndAddress     Highest CPU bus address
+       u8      RangeType      See range types
+       === Virtual Boy fields ===
+       u32     StartAddress   Lowest CPU bus address
+       u32     EndAddress     Highest CPU bus address
+       u8      RangeType      See range types
+    */
+
+    /* Count field is not present */
+    if (src + 3 > length)
+        return (size_t) -1;
+
+    /* Advance past Ranges field */
+    return src + 3 + size * ((uint16_t) bytes[src + 2] << 8 | bytes[src + 1]);
+}
+
+/* Skip ISX symbol record */
+static size_t isxSymbol(uint8_t *bytes,size_t length,size_t src,size_t size) {
+    size_t count; /* Number of symbols */
+    size_t x;     /* Iterator */
+
+    /*
+      u8       Type          =0x04 (SNES) or 0x14 (Virtual Boy)
+      u16      Count         Number of symbols
+      Symbol[] Symbols
+       u8       NameLength   Number of bytes in Name
+       u8[]     Name         Symbol name
+       === SNES fields ===
+       u8       Flags        Undocumented
+       u8       Bank         Cartridge bank number
+       u16      Address      CPU bus address
+       === Virtual Boy fields ===
+       u16      Flags        Undocumented
+       u32      Address      CPU bus address
+    */
+
+    /* Count field is not present */
+    if (src + 3 > length)
+        return (size_t) -1;
+
+    /* Working variables */
+    count = (uint16_t) bytes[src + 2] << 8 | bytes[src + 1];
+    src  += 3;
+
+    /* Process all symbols */
+    for (x = 0; x < count; x++) {
+
+        /* NameLength field is not present */
+        if (src > length)
+            return (size_t) -1;
+
+        /* Advance past remainder of symbol */
+        src += size + bytes[src];
+
+        /* Remainder of symbol is not present */
+        if (src > length)
+            return (size_t) -1;
+    }
+
+    return src;
+}
+
+/* Skip ISX system record */
+static size_t isxSystem(uint8_t *bytes, size_t length, size_t src) {
+    /*
+      u8   Type         =0x20, 0x21 or 0x22
+      u32  DataLength   Number of bytes in Data
+      u8[] Data         Record data
+    */
+
+    /* DataLength field is not present */
+    if (src + 5 > length)
+        return (size_t) -1;
+
+    /* Advance past Data field */
+    return src + 5 + (
+        (uint32_t) bytes[src + 4] << 24 | (uint32_t) bytes[src + 3] << 16 |
+        (uint32_t) bytes[src + 2] <<  8 |            bytes[src + 1]
+    );
+}
+
+
+
+/***************************** Library Functions *****************************/
+
+/* Decode an ISX debugger file to a Virtual Boy ROM */
+static void* isxFrom(uint8_t *bytes, size_t length, size_t *romLength) {
+    uint32_t addr;    /* Code record base address */
+    uint32_t highMin; /* Lowest address in upper half of ROM */
+    uint32_t lowMax;  /* Highest address in lower half of ROM */
+    uint8_t *rom;     /* Output ROM */
+    uint32_t size;    /* Code record size in bytes */
+    size_t   src;     /* Input position */
+    size_t   start;   /* Offset of first record */
+
+    /* Error checking */
+    if (length < 3)
+        return NULL;
+
+    /* Working variables */
+    highMin = 0xFFFFFF;
+    lowMax  = 0x000000;
+    size    = 0;
+    start   = strncmp((char *) bytes, "ISX", 3) ? 0 : 32;
+
+    /* First pass: determine the size of the ROM */
+    for (src = start; src < length;) {
+        switch (bytes[src]) {
+
+            case 0x11: /* Code (Virtual Boy) */
+
+                /* Decode record fields */
+                src = isx11(bytes, length, src, &addr, &size);
+                if (src > length)
+                    return NULL;
+
+                /* Validate address and data size */
+                addr &= 0x07FFFFFF;
+                if (
+                    addr < 0x07000000 ||
+                    0x08000000 - addr < size
+                ) return NULL;
+                addr &= 0x00FFFFFF;
+
+                /* Requires 16 MiB */
+                if (addr < 0x800000 && addr + size > 0x800000) {
+                    highMin = 0x800000;
+                    lowMax  = 0x7FFFFF;
+                }
+
+                /* Map from top of ROM space */
+                else if (addr & 0x800000) {
+                    if (addr < highMin)
+                        highMin = addr;
+                }
+
+                /* Map from bottom of ROM space */
+                else {
+                    addr += size - 1;
+                    if (addr > lowMax)
+                        lowMax = addr;
+                }
+ 
+                break;
+
+            case 0x01: /* Code (SNES) */
+                src = isx01    (bytes, length, src   ); break;
+            case 0x03: /* Range (SNES) */
+                src = isxRange (bytes, length, src, 6); break;
+            case 0x04: /* Symbol (SNES) */
+                src = isxSymbol(bytes, length, src, 5); break;
+            case 0x13: /* Range (Virtual Boy) */
+                src = isxRange (bytes, length, src, 9); break;
+            case 0x14: /* Symbol (Virtual Boy) */
+                src = isxSymbol(bytes, length, src, 7); break;
+            case 0x20: /* System (undocumented) */
+            case 0x21: /* System (undocumented) */
+            case 0x22: /* System (undocumented) */
+                src = isxSystem(bytes, length, src    ); break;
+            default: /* Invalid record type */
+                return NULL;
+        }
+
+        /* Record contains invalid data */
+        if (src > length)
+            return NULL;
+    }
+
+    /* Produce a ROM buffer of minimal size to fit all the code records */
+    for (
+        src = 1;
+        src < lowMax + 0x1000001 - highMin;
+        src <<= 1
+    );
+    rom = VBU_REALLOC(NULL, src);
+    if (rom == NULL)
+        return NULL;
+    *romLength = src;
+    memset(rom, 0x00, src);
+
+    /* Second pass: fill the ROM buffer with the code records */
+    for (src = start; src < length;) {
+        switch (bytes[src]) {
+
+            case 0x11: /* Code (Virtual Boy) */
+                src = isx11(bytes, length, src, &addr, &size);
+                memcpy(&rom[addr & (*romLength-1)], &bytes[src - size], size);
+                break;
+
+            case 0x01: /* Code (SNES) */
+                src = isx01    (bytes, length, src    ); break;
+            case 0x03: /* Range (SNES) */
+                src = isxRange (bytes, length, src,  9); break;
+            case 0x04: /* Symbol (SNES) */
+                src = isxSymbol(bytes, length, src,  5); break;
+            case 0x13: /* Range (Virtual Boy) */
+                src = isxRange (bytes, length, src, 12); break;
+            case 0x14: /* Symbol (Virtual Boy) */
+                src = isxSymbol(bytes, length, src,  7); break;
+            case 0x20: /* System (undocumented) */
+            case 0x21: /* System (undocumented) */
+            case 0x22: /* System (undocumented) */
+                src = isxSystem(bytes, length, src    ); break;
+        }
+    }
+
+    return rom;
+}
+
+
+
+#endif /* VBUAPI */

util/vbu.c

@@ -0,0 +1,78 @@
+#ifndef VBUAPI
+#define VBUAPI
+#endif
+#include <stdio.h>
+#include <string.h>
+#include <vbu.h>
+
+/* Memory management */
+#ifndef VBU_REALLOC
+    #include <stdlib.h>
+    #define VBU_REALLOC realloc
+#else
+    extern void* VBU_REALLOC(void *, size_t);
+#endif
+
+
+
+/***************************** Library Functions *****************************/
+
+/* Sign-extend an integer of variable width */
+static int32_t SignExtend(int32_t value, int32_t bits) {
+    #ifndef VB_SIGNED_PROPAGATE
+        value &= ~((uint32_t) 0xFFFFFFFF << bits);
+        bits   = (int32_t) 1 << (bits - (int32_t) 1);
+        return (value ^ bits) - bits;
+    #else
+        return value << (32 - bits) >> (32 - bits);
+    #endif
+}
+
+
+
+/******************************** Sub-Modules ********************************/
+
+#include "disassembler.c"
+#include "isx.c"
+
+
+
+/******************************* API Commands ********************************/
+
+/* Determine the size in bytes of an instruction */
+VBUAPI int vbuCodeSize(VB *sim, uint32_t address) {
+    int opcode = vbRead(sim, address, VB_U16) >> 10 & 63;
+    return opcode < 0x20 || opcode == 0x32 || opcode == 0x36 ? 2 : 4;
+}
+
+/* Initialize disassembler options with default settings */
+VBUAPI VBU_DasmConfig* vbuDasmInit(VBU_DasmConfig *config) {
+    config->bcondNotation     = VBU_JOINED;
+    config->conditionCase     = VBU_LOWER;
+    config->conditionCL       = VBU_L;
+    config->conditionEZ       = VBU_Z;
+    config->conditionNotation = VBU_NAMES;
+    config->hexCase           = VBU_UPPER;
+    config->hexNotation       = VBU_0X;
+    config->immediateNotation = VBU_NONE;
+    config->memoryNotation    = VBU_OUTSIDE;
+    config->mnemonicCase      = VBU_UPPER;
+    config->operandOrder      = VBU_DEST_LAST;
+    config->programCase       = VBU_LOWER;
+    config->programNotation   = VBU_NAMES;
+    config->setfNotation      = VBU_SPLIT;
+    config->systemCase        = VBU_LOWER;
+    config->systemNotation    = VBU_NAMES;
+    return config;
+}
+
+/* Disassemble from a simulation */
+VBUAPI VBU_DasmLine* vbuDisassemble(VB *sim, uint32_t address,
+    VBU_DasmConfig *config, unsigned length, int line) {
+    return dasmDisassemble(sim, address, config, length, line);
+}
+
+/* Decode an ISX debugger file to a Virtual Boy ROM */
+VBUAPI void* vbuFromISX(void *bytes, size_t length, size_t *romLength) {
+    return isxFrom(bytes, length, romLength);
+}

util/vbu.h

@@ -0,0 +1,99 @@
+#ifndef VBU_H_
+#define VBU_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef VBUAPI
+#define VBUAPI extern
+#endif
+
+/* Header includes */
+#include <vb.h>
+
+
+
+/********************************* Constants *********************************/
+
+/* Disassembler options */
+#define VBU_0X         0
+#define VBU_C          1
+#define VBU_DEST_FIRST 1
+#define VBU_DEST_LAST  0
+#define VBU_DOLLAR     1
+#define VBU_E          0
+#define VBU_H          2
+#define VBU_INSIDE     1
+#define VBU_JOINED     0
+#define VBU_L          0
+#define VBU_LOWER      1
+#define VBU_NAMES      1
+#define VBU_NONE       0
+#define VBU_NUMBER     1
+#define VBU_NUMBERS    0
+#define VBU_OUTSIDE    0
+#define VBU_SPLIT      1
+#define VBU_UPPER      0
+#define VBU_Z          1
+
+
+
+/*********************************** Types ***********************************/
+
+/* Disassembler text options */
+typedef struct {               /* Defaults listed first */
+    uint8_t bcondNotation;     /* JOINED, SPLIT */
+    uint8_t conditionCase;     /* LOWER, UPPER */
+    uint8_t conditionCL;       /* L, C */
+    uint8_t conditionEZ;       /* Z, E */
+    uint8_t conditionNotation; /* NAMES, NUMBERS */
+    uint8_t hexCase;           /* UPPER, LOWER */
+    uint8_t hexNotation;       /* 0X, H, DOLLAR */
+    uint8_t immediateNotation; /* NONE, NUMBER */
+    uint8_t memoryNotation;    /* OUTSIDE, INSIDE */
+    uint8_t mnemonicCase;      /* UPPER, LOWER */
+    uint8_t operandOrder;      /* DEST_LAST, DEST_FIRST */
+    uint8_t programCase;       /* LOWER, UPPER */
+    uint8_t programNotation;   /* NAMES, NUMBERS */
+    uint8_t setfNotation;      /* SPLIT, JOINED */
+    uint8_t systemCase;        /* LOWER, UPPER */
+    uint8_t systemNotation;    /* NAMES, NUMBERS */
+} VBU_DasmConfig;
+
+/* Disassembler output line */
+typedef struct {
+
+    /* Parsed */
+    uint32_t address;    /* Memory address */
+    uint16_t code[4];    /* Instruction bytes */
+    uint8_t  codeLength; /* Number of items in code */
+    uint8_t  isPC;       /* Set if PC is on this line */
+
+    /* Display text */
+    struct {
+        char   *address;        /* Memory address */
+        char   *code[4];        /* Instruction bytes */
+        char   *mnemonic;       /* Instruction mnemonic */
+        char   *operands[3];    /* Instruction operands */
+        uint8_t operandsLength; /* Number of items in operands */
+    } text;
+
+} VBU_DasmLine;
+
+
+
+/******************************* API Commands ********************************/
+
+VBUAPI int             vbuCodeSize   (VB *sim, uint32_t address);
+VBUAPI VBU_DasmConfig* vbuDasmInit   (VBU_DasmConfig *config);
+VBUAPI VBU_DasmLine*   vbuDisassemble(VB *sim, uint32_t address, VBU_DasmConfig *config, unsigned length, int line);
+VBUAPI void*           vbuFromISX    (void *bytes, size_t length, size_t *romLength);
+
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* VBU_H_ */

web/Audio.js

@@ -0,0 +1,99 @@
+"use strict";
+
+// Dedicated audio output processor
+class Audio extends AudioWorkletProcessor {
+
+    // Instance fields
+    buffers; // Input sample buffer queue
+    core;    // Communications with core thread
+    dom;     // Communications with DOM thread
+    offset;  // Offset into oldest buffer
+
+
+
+    ///////////////////////// Initialization Methods //////////////////////////
+
+    constructor() {
+        super();
+        this.port.onmessage = async e=>{
+            await this.#construct(e.data.core);
+            this.port.postMessage(0);
+        };
+    }
+
+    // Asynchronous constructor
+    async #construct(core) {
+
+        // Configure instance fields
+        this.buffers = [];
+        this.core    = core;
+        this.dom     = this.port;
+        this.offset  = 0;
+
+        // Configure communications
+        this.core.onmessage = e=>this.#onCore(e.data);
+        this.dom .onmessage = e=>this.#onDOM (e.data);
+    }
+
+
+
+    ///////////////////////////// Public Methods //////////////////////////////
+
+    // Produce output samples (called by the user agent)
+    process(inputs, outputs, parameters) {
+        let output = outputs[0];
+        let length = output [0].length;
+        let empty  = null;
+
+        // Process all samples
+        for (let x = 0; x < length;) {
+
+            // No bufferfed samples are available
+            if (this.buffers.length == 0) {
+                for (; x < length; x++)
+                    output[0][x] = output[1][x] = 0;
+                break;
+            }
+
+            // Transfer samples from the oldest buffer
+            let buffer = this.buffers[0];
+            let y      = this.offset;
+            for (; x < length && y < buffer.length; x++, y+=2) {
+                output[0][x] = buffer[y    ];
+                output[1][x] = buffer[y + 1];
+            }
+
+            // Advance to the next buffer
+            if (y == buffer.length) {
+                if (empty == null)
+                    empty = [];
+                empty.push(this.buffers.shift().buffer);
+                this.offset = 0;
+            }
+
+            // Buffer is not empty
+            else this.offset = y;
+        }
+
+        // Return emptied sample buffers to the core thread
+        if (empty != null)
+            this.core.postMessage(empty, empty);
+
+        return true;
+    }
+
+
+
+    ///////////////////////////// Event Handlers //////////////////////////////
+
+    // Message received from core thread
+    #onCore(e) {
+        this.buffers.push(new Float32Array(e));
+    }
+
+    // Message received from DOM thread
+    #onDOM(e) {
+    }
+
+}
+registerProcessor("shrooms-vb", Audio);

web/Constants.js

@@ -0,0 +1,88 @@
+"use strict";
+export default {
+
+    // Core
+    VB: {
+
+        // System registers
+        ADTRE: 25,
+        CHCW : 24,
+        ECR  :  4,
+        EIPC :  0,
+        EIPSW:  1,
+        FEPC :  2,
+        FEPSW:  3,
+        PIR  :  6,
+        PSW  :  5,
+        TKCW :  7,
+
+        // Memory access data types
+        S8 : 0,
+        U8 : 1,
+        S16: 2,
+        U16: 3,
+        S32: 4,
+        F32: 5,
+
+        // Option keys
+        PSEUDO_HALT: 0,
+
+        // Controller buttons
+        PWR: 0x0001,
+        SGN: 0x0002,
+        A  : 0x0004,
+        B  : 0x0008,
+        RT : 0x0010,
+        LT : 0x0020,
+        RU : 0x0040,
+        RR : 0x0080,
+        LR : 0x0100,
+        LL : 0x0200,
+        LD : 0x0400,
+        LU : 0x0800,
+        STA: 0x1000,
+        SEL: 0x2000,
+        RL : 0x4000,
+        RD : 0x8000
+    },
+
+    // Utility
+    VBU: {
+
+        // Disassembler options
+        "0X"      : 0,
+        C         : 1,
+        DEST_FIRST: 1,
+        DEST_LAST : 0,
+        DOLLAR    : 1,
+        E         : 0,
+        H         : 2,
+        INSIDE    : 1,
+        JOINED    : 0,
+        L         : 0,
+        LOWER     : 1,
+        NAMES     : 1,
+        NONE      : 0,
+        NUMBER    : 1,
+        NUMBERS   : 0,
+        OUTSIDE   : 0,
+        SPLIT     : 1,
+        UPPER     : 0,
+        Z         : 1
+    },
+
+    // Web interface
+    web: {
+
+        // Break types
+        BREAK_FRAME: 1,
+        BREAK_POINT: 2,
+
+        // Anaglyph colors
+        STEREO_CYAN   : 0x00C6F0,
+        STEREO_GREEN  : 0x00B400,
+        STEREO_MAGENTA: 0xC800FF,
+        STEREO_RED    : 0xFF0000
+    }
+
+};

web/Core.js

@@ -0,0 +1,611 @@
+"use strict";
+import Constants from /***/"./Constants.js";
+
+
+
+//////////////////////////////////// Core /////////////////////////////////////
+
+// Emulation processor
+new class Core {
+
+    // Instance fields
+    audio;       // Audio communication
+    automatic;   // Automatic emulation state
+    clocked;     // Clocked emulation state
+    dom;         // DOM communication
+    mallocs;     // Memory allocations by pointer
+    pointerType; // TypedArray for WebAssembly pointers
+    sims;        // Simulations by pointer
+
+
+
+    ///////////////////////// Initialization Methods //////////////////////////
+
+    constructor() {
+        onmessage = async e=>{
+            await this.#construct(e.data.audio, e.data.wasmUrl);
+            this.dom.postMessage(0);
+        };
+    }
+
+    // Asynchronous constructor
+    async #construct(audio, wasmUrl) {
+
+        // Configure instance fields
+        this.mallocs = new Map();
+        this.sims    = new Map();
+
+        // DOM thread communication
+        this.dom = globalThis;
+        this.dom.onmessage = e=>this[e.data.command](e.data);
+
+        // Instantiate the WebAssembly module
+        this.wasm = (await WebAssembly.instantiateStreaming(
+            fetch(wasmUrl), {
+            env: {
+                emscripten_notify_memory_growth: ()=>this.#onGrowth()
+            }
+        }));
+        Object.assign(this, this.wasm.instance.exports);
+        this.pointerType = this.PointerSize() == 8 ?
+            BigUint64Array : Uint32Array;
+
+        // Configure audio state
+        this.audio = audio;
+        audio.buffers = [0,0,0].map(v=>new Float32Array(41700 / 50 * 2));
+        audio.samples =
+            this.#malloc(41700 / 50 * 2, audio, "samples", Float32Array);
+        audio.onmessage = e=>this.#onAudio(e.data);
+
+        // Configure emulation states
+        this.automatic = { emulating: false };
+        this.clocked   = {};
+        for (let s of [ this.automatic, this.clocked ]) {
+            s.clocks   = this.#malloc(1, s, "clocks"  , Uint32Array);
+            s.pointers = this.#malloc(1, s, "pointers", this.pointerType);
+            s.sims     = [];
+        }
+
+    }
+
+
+
+    ////////////////////////////// Core Commands //////////////////////////////
+
+    // Instantiate sims
+    createSims(message) {
+        let sims = new Array(message.count);
+        let size = this.vbSizeOf();
+
+        // Process all sims
+        for (let x = 0; x < message.count; x++) {
+            let sim = {
+                canvas  : null,
+                keys    : Constants.VB.SGN,
+                pointer : sims[x] = this.CreateSim()
+            };
+            this.sims.set(sim.pointer, sim);
+
+            // Video
+            sim.pixels = this.#getPixels(sim);
+            sim.image  = new ImageData(sim.pixels, 384, 224);
+
+            // Audio
+            sim.samples = this.#noalloc(
+                this.GetExtSamples(sim.pointer),
+                41700 / 50 * 2, sim, "samples", Float32Array
+            );
+
+        }
+
+        this.dom.postMessage({
+            sims    : sims,
+            promised: true
+        });
+    }
+
+    // Produce disassembly from a sim
+    disassemble(message) {
+
+        // Disassemble from the simulation
+        let dasm = message.config == null ?
+            this.vbuDisassemble(
+                message.sim,
+                message.address,
+                0,
+                message.length,
+                message.line
+            )
+        :
+            this.Disassemble(
+                message.config.bcondNotation,
+                message.config.conditionCase,
+                message.config.conditionCL,
+                message.config.conditionEZ,
+                message.config.conditionNotation,
+                message.config.hexCase,
+                message.config.hexNotation,
+                message.config.immediateNotation,
+                message.config.memoryNotation,
+                message.config.mnemonicCase,
+                message.config.operandOrder,
+                message.config.programCase,
+                message.config.programNotation,
+                message.config.setfNotation,
+                message.config.systemCase,
+                message.config.systemNotation,
+                message.sim,
+                message.address,
+                message.length,
+                message.line
+            )
+        ;
+
+        // A memory error occurred
+        if (dasm == 0) {
+            this.dom.postMessage({
+                promised: message.promised,
+                success : false
+            });
+            return;
+        }
+
+        // Retrieve all disassembly data into a working buffer
+        let pointer = this.Realloc(0, message.length * 17 * 4);
+        let buffer  = new Uint32Array(
+            this.memory.buffer, pointer, message.length * 17);
+        this.GetDasm(pointer, dasm, message.length);
+
+        // Consume output lines
+        let lines = new Array(message.length);
+        for (let x = 0, z = 0; x < lines.length; x++) {
+            let line = lines[x] = { text: {} };
+            line.address      = buffer[z++];
+            line.code         = new Array(buffer[z++]);
+            for (let y = 0; y < line.code.length; y++)
+                line.code[y]  = buffer[z++];
+            z += 4 - line.code.length;
+            line.isPC         = buffer[z++] != 0;
+            line.text.address = this.#string(dasm + buffer[z++], true);
+            line.text.code    = new Array(line.code.length);
+            for (let y = 0; y < line.code.length; y++)
+                line.text.code[y] = this.#string(dasm + buffer[z++], true);
+            z += 4 - line.code.length;
+            line.text.mnemonic = this.#string(dasm + buffer[z++], true);
+            line.text.operands = new Array(buffer[z++]);
+            for (let y = 0; y < line.text.operands.length; y++)
+                line.text.operands[y] = this.#string(dasm + buffer[z++], true);
+            z += 3 - line.text.operands.length;
+        }
+
+        // Memory cleanup
+        this.Realloc(pointer, 0);
+        this.Realloc(dasm   , 0);
+
+        // Send response
+        this.dom.postMessage({
+            success : true,
+            lines   : lines,
+            promised: message.promised
+        });
+    }
+
+    // Emulate automatically
+    emulateAutomatic(message) {
+
+        // Configure sims
+        this.automatic.pointers = this.#realloc(
+            this.automatic.pointers, message.sims.length);
+        for (let x = 0; x < message.sims.length; x++) {
+            this.automatic.pointers[x] = message.sims[x];
+            this.automatic.sims    [x] = this.sims.get(message.sims[x]);
+        }
+
+        // Notify the DOM thread
+        this.dom.postMessage({ promised: true });
+
+        // Begin automatic emulation
+        this.automatic.emulating = true;
+        this.#autoEmulate();
+    }
+
+    // Emulate for a given number of clocks
+    emulateClocked(message) {
+
+        // Configure sims
+        this.clocked.pointers = this.#realloc(
+            this.clocked.pointers, message.sims.length);
+        for (let x = 0; x < message.sims.length; x++) {
+            this.clocked.pointers[x] = message.sims[x];
+            this.clocked.sims    [x] = this.sims.get(message.sims[x]);
+        }
+
+        // Process simulations
+        let broke = false;
+        this.clocked.clocks[0] = message.clocks;
+        while (!broke && this.clocked.clocks[0] != 0) {
+
+            // Process simulations until a suspension
+            this.Emulate(
+                this.clocked.pointers.pointer,
+                message.sims.length,
+                this.clocked.clocks.pointer
+            );
+
+            // Monitor break conditions
+            for (let x = 0; x < message.sims.length; x++) {
+                let sim    = this.clocked.sims[x];
+                sim.breaks = this.GetBreaks(sim.pointer);
+                if (breaks & Constants.web.BREAK_POINT)
+                    broke = true;
+            }
+
+        }
+
+        // Update images
+        for (let sim of this.clocked.sims) {
+            if (!(sim.breaks & Constants.web.BREAK_FRAME))
+                continue;
+            this.GetPixels(sim.pointer);
+            sim.context.putImageData(sim.image, 0, 0);
+        }
+
+        // Notify DOM thread
+        this.dom.postMessage({
+            promised: true,
+            broke   : broke,
+            clocks  : this.clocked.clocks[0]
+        });
+    }
+
+    // Attempt to produce a ROM from an ISX debugger file
+    fromISX(message) {
+
+        // Transfer the input data into WebAssembly memory
+        let input = new Uint8Array(message.data);
+        let inPtr = this.Realloc(0, input.length);
+        let inMem = new Uint8Array(this.memory.buffer, inPtr, input.length);
+        for (let x = 0; x < input.length; x++)
+            inMem[x] = input[x];
+
+        // Attempt to decode the ISX file as a ROM
+        let outPtr = this.FromISX(inPtr, input.length);
+        this.Realloc(inPtr, 0);
+
+        // The data is not an ISX file
+        if (outPtr == 0) {
+            this.dom.postMessage({ promised: true, data: null });
+            return;
+        }
+
+        // Transfer the decoded ROM from WebAssembly memory
+        let output = new Uint8Array(this.GetISXLength(outPtr));
+        let outMem = new Uint8Array(this.memory.buffer,
+            this.GetISXROM(outPtr), output.length);
+        for (let x = 0; x < output.length; x++)
+            output[x] = outMem[x];
+        this.Realloc(outPtr, 0);
+
+        // Notify DOM thread
+        this.dom.postMessage({
+            promised: true,
+            data    : output.buffer
+        }, [ output.buffer ]);
+    }
+
+    // Reset simulation state
+    reset(message) {
+        this.vbReset(message.sim);
+        this.dom.postMessage({ promised: true });
+    }
+
+    // Specify anaglyph colors
+    setAnaglyph(message) {
+        this.SetAnaglyph(message.sim, message.left, message.right);
+        this.dom.postMessage({ promised: true });
+    }
+
+    // Specify the OffscreenCanvas that goes with a sim
+    setCanvas(message) {
+        let sim = this.sims.get(message.sim);
+        sim.canvas  = message.canvas;
+        sim.context = sim.canvas.getContext("2d");
+        sim.context.putImageData(sim.image, 0, 0);
+        this.dom.postMessage({ promised: true });
+    }
+
+    // Specify a game pak RAM buffer
+    setCartRAM(message) {
+        this.#setCartMemory(message.sim, message.data,
+            this.vbGetCartRAM, this.vbSetCartRAM);
+    }
+
+    // Specify a game pak ROM buffer
+    setCartROM(message) {
+        this.#setCartMemory(message.sim, message.data,
+            this.vbGetCartROM, this.vbSetCartROM);
+    }
+
+    // Specify new game pad keys
+    setKeys(message) {
+        this.vbSetKeys(message.sim, message.keys);
+        this.dom.postMessage({ promised: true });
+    }
+
+    // Specify audio panning
+    setPanning(message) {
+        this.SetPanning(message.sim, message.panning);
+        this.dom.postMessage({ promised: true });
+    }
+
+    // Specify a new communication peer
+    setPeer(message) {
+        let orphaned = [];
+        let prev     = this.vbGetPeer(message.sim);
+        if (prev != message.peer) {
+            if (prev != 0) // Sim's previous peer has been orphaned
+                orphaned.push(prev);
+            if (message.peer != 0) {
+                prev = this.vbGetPeer(message.peer);
+                if (prev != null) // Peer's previous peer has been orphaned
+                    orphaned.push(prev);
+            }
+            this.vbSetPeer(message.sim, message.peer);
+        }
+        this.dom.postMessage({
+            orphaned: orphaned,
+            promised: true
+        });
+    }
+
+    // Specify audio volume
+    setVolume(message) {
+        this.SetVolume(message.sim, message.volume);
+        this.dom.postMessage({ promised: true });
+    }
+
+    // Suspend automatic emulation
+    suspend(message) {
+        this.automatic.emulating = false;
+        this.dom.postMessage({ promised: true });
+    }
+
+
+
+    ///////////////////////////// Event Handlers //////////////////////////////
+
+    // Message from audio thread
+    #onAudio(e) {
+
+        // Output staged images
+        if (this.automatic.emulating && this.audio.buffers.length == 0) {
+            for (let sim of this.automatic.sims)
+                sim.context.putImageData(sim.image, 0, 0);
+        }
+
+        // Acquire the emptied buffers and resume emulation
+        this.audio.buffers.push(... e.map(b=>new Float32Array(b)));
+        this.#autoEmulate();
+    }
+
+    // WebAssembly memory has grown
+    #onGrowth() {
+        for (let prev of this.mallocs.values()) {
+            let buffer = new prev.constructor(
+                this.memory.buffer, prev.pointer, prev.size);
+            Object.assign(buffer, {
+                assign : prev.assign,
+                pointer: prev.pointer,
+                size   : prev.size,
+                target : prev.target
+            });
+            this.mallocs.set(buffer.pointer, buffer);
+            this.#updateTarget(buffer);
+        }
+        for (let sim of this.sims.values()) {
+            sim.pixels = this.#getPixels(sim);
+            sim.image  = new ImageData(sim.pixels, 384, 224);
+        }
+    }
+
+
+
+    ///////////////////////////// Private Methods /////////////////////////////
+
+    // Automatic emulation processing
+    #autoEmulate() {
+
+        // Error checking
+        if (!this.automatic.emulating)
+            return;
+
+        // Process all remaining audio buffers
+        while (this.audio.buffers.length != 0) {
+
+            // Reset sample output
+            for (let sim of this.automatic.sims) {
+                this.vbSetSamples(sim.pointer, sim.samples.pointer,
+                    Constants.VB.F32, 41700 / 50);
+            }
+
+            // Process all clocks
+            this.automatic.clocks[0] = 400000; // 0.02s
+            while (this.automatic.clocks[0] != 0) {
+                this.Emulate(
+                    this.automatic.pointers.pointer,
+                    this.automatic.sims.length,
+                    this.automatic.clocks.pointer
+                );
+
+                // Too many buffers left to output video
+                if (this.audio.buffers.length > 2)
+                    continue;
+
+                // Stage the next video image
+                for (let sim of this.automatic.sims) {
+                    let breaks = this.GetBreaks(sim.pointer);
+                    if (breaks & Constants.web.BREAK_FRAME)
+                        this.GetPixels(sim.pointer);
+                }
+
+            }
+
+            // Mix and output audio samples
+            let buffer = this.audio.buffers.shift();
+            this.Mix(
+                this.audio.samples.pointer,
+                this.automatic.pointers.pointer,
+                this.automatic.sims.length
+            );
+            for (let x = 0; x < buffer.length; x++)
+                buffer[x] = this.audio.samples[x];
+            this.audio.postMessage(buffer.buffer, [ buffer.buffer ]);
+
+            // Output staged images if there's one audio buffer to go
+            if (this.audio.buffers.length != 1)
+                continue;
+            for (let sim of this.automatic.sims)
+                sim.context.putImageData(sim.image, 0, 0);
+        }
+
+    }
+
+    // Delete an allocated buffer in WebAssembly memory
+    #free(buffer) {
+        this.mallocs.delete(buffer.pointer);
+        this.Realloc(buffer.pointer, 0);
+    }
+
+    // Register a sim's pixel buffer
+    #getPixels(sim) {
+        return this.#noalloc(
+            this.GetExtPixels(sim.pointer),
+            384*224*4, sim, "pixels", Uint8ClampedArray
+        );
+    }
+
+    // Allocate memory in WebAssembly and register the buffer
+    #malloc(count, target = null, assign = null, type = Uint8ClampedArray) {
+        return this.#noalloc(
+            this.Realloc(0, count * type.BYTES_PER_ELEMENT),
+            count, target, assign, type
+        );
+    }
+
+    // Register a buffer in WebAssembly memory without allocating it
+    #noalloc(pointer, count, target=null, assign=null, type=Uint8ClampedArray){
+        let buffer = new type(this.memory.buffer, pointer, count);
+        Object.assign(buffer, {
+            assign : assign?.split("."),
+            count  : count,
+            pointer: pointer,
+            target : target
+        });
+        this.mallocs.set(pointer, buffer);
+        return buffer;
+    }
+
+    // Resize a previously allocated buffer in WebAssembly memory
+    #realloc(prev, count) {
+        this.mallocs.delete(prev.pointer);
+        let pointer = this.Realloc(prev.pointer,
+            count * prev.constructor.prototype.BYTES_PER_ELEMENT);
+        let buffer  = new prev.constructor(this.memory.buffer, pointer, count);
+        Object.assign(buffer, {
+            assign : prev.assign,
+            count  : count,
+            pointer: pointer,
+            target : prev.target
+        });
+        this.mallocs.set(pointer, buffer);
+        this.#updateTarget(buffer);
+        return buffer;
+    }
+
+    // Compute anaglyph color values
+    #setAnaglyph(sim, left, right) {
+
+        // Split out the RGB channels
+        let color  = left | right;
+        let stereo = [
+            color >> 16 & 0xFF,
+            color >>  8 & 0xFF,
+            color       & 0xFF
+        ];
+
+        // Compute scaled RGB values by output level
+        sim.anaglyph = new Array(256);
+        for (let x = 0; x < 256; x++) {
+            let level = sim.anaglyph[x] = new Array(3);
+            for (let y = 0; y < 3; y++)
+                level[y] = Math.round(x * stereo[y] / 255.0);
+        }
+
+        // Determine which channels are in each eye
+        sim.anaglyph.left  = [];
+        sim.anaglyph.right = [];
+        for (let x = 0, y = 16; x < 3; x++, y -= 8) {
+            if (left  >> y & 0xFF)
+                sim.anaglyph.left .push(x);
+            if (right >> y & 0xFF)
+                sim.anaglyph.right.push(x);
+        }
+
+    }
+
+    // Specify a game pak memory buffer
+    #setCartMemory(sim, mem, getter, setter) {
+
+        // Working variables
+        let cart = new Uint8Array(mem);
+        let prev = getter(sim);
+        let cur  = this.Realloc(0, cart.length);
+            mem  = new Uint8Array(this.memory.buffer, cur, cart.length);
+
+        // Transfer the data into core memory
+        for (let x = 0; x < mem.length; x++)
+            mem[x] = cart[x];
+
+        // Assign the ROM to the simulation
+        let success = setter(sim, cur, mem.length) == 0;
+        if (success) {
+            if (prev != 0)
+                this.Realloc(prev, 0);
+        } else this.Realloc(cur, 0);
+
+        // Reply to the DOM thread
+        this.dom.postMessage({
+            success : success,
+            promised: true
+        });
+    }
+
+    // Read a C string from WebAssembly memory
+    #string(address, indirect = false) {
+        if (address == 0)
+            return null;
+
+        if (indirect) {
+            let next = new this.pointerType(this.memory.buffer, address, 1)[0];
+            address = next;
+        }
+
+        let length = 0;
+        let memory = new Uint8Array(this.memory.buffer);
+        for (let addr = address; memory[addr++] != 0; length++);
+        return (Array.from(memory.slice(address, address + length))
+            .map(b=>String.fromCodePoint(b)).join(""));
+    }
+
+    // Update an allocated buffer's assignment in its monitor object
+    #updateTarget(buffer) {
+        if (buffer.target == null)
+            return;
+        let obj    = buffer.target;
+        let assign = buffer.assign.slice();
+        while (assign.length > 1)
+            obj = obj[assign.shift()];
+        obj[assign[0]] = buffer;
+    }
+
+}();

web/VB.js

@@ -0,0 +1,976 @@
+"use strict";
+import Constants from /**/"./Constants.js";
+
+// Instantiation guard
+const GUARD = Symbol();
+
+
+
+///////////////////////////////// DasmConfig //////////////////////////////////
+
+// Disassembler option settings
+class DasmConfig {
+
+    // Instance fields
+    #bcondNotation;
+    #conditionCase;
+    #conditionCL;
+    #conditionEZ;
+    #conditionNotation;
+    #hexCase;
+    #hexNotation;
+    #immediateNotation;
+    #memoryNotation;
+    #mnemonicCase;
+    #operandOrder;
+    #programCase;
+    #programNotation;
+    #setfNotation;
+    #systemCase;
+    #systemNotation;
+
+
+
+    ///////////////////////// Initialization Methods //////////////////////////
+
+    constructor() {
+        this.#bcondNotation     = Constants.VBU.JOINED;
+        this.#conditionCase     = Constants.VBU.LOWER;
+        this.#conditionCL       = Constants.VBU.L;
+        this.#conditionEZ       = Constants.VBU.Z;
+        this.#conditionNotation = Constants.VBU.NAMES;
+        this.#hexCase           = Constants.VBU.UPPER;
+        this.#hexNotation       = Constants.VBU["0X"];
+        this.#immediateNotation = Constants.VBU.NONE;
+        this.#memoryNotation    = Constants.VBU.OUTSIDE;
+        this.#mnemonicCase      = Constants.VBU.UPPER;
+        this.#operandOrder      = Constants.VBU.DEST_LAST;
+        this.#programCase       = Constants.VBU.LOWER;
+        this.#programNotation   = Constants.VBU.NAMES;
+        this.#setfNotation      = Constants.VBU.SPLIT;
+        this.#systemCase        = Constants.VBU.LOWER;
+        this.#systemNotation    = Constants.VBU.NAMES;
+    }
+
+
+
+    /////////////////////////// Property Accessors ////////////////////////////
+
+    get bcondNotation() { return this.#bcondNotation; }
+    set bcondNotation(value) {
+        switch (value) {
+            case Constants.VBU.JOINED:
+            case Constants.VBU.SPLIT : break;
+            default: return;
+        }
+        this.#bcondNotation = value;
+    }
+
+    get conditionCase() { return this.#conditionCase; }
+    set conditionCase(value) {
+        switch (value) {
+            case Constants.VBU.LOWER:
+            case Constants.VBU.UPPER: break;
+            default: return;
+        }
+        this.#conditionCase = value;
+    }
+
+    get conditionCL() { return this.#conditionCL; }
+    set conditionCL(value) {
+        switch (value) {
+            case Constants.VBU.C:
+            case Constants.VBU.L: break;
+            default: return;
+        }
+        this.#conditionCL = value;
+    }
+
+    get conditionEZ() { return this.#conditionEZ; }
+    set conditionEZ(value) {
+        switch (value) {
+            case Constants.VBU.E:
+            case Constants.VBU.Z: break;
+            default: return;
+        }
+        this.#conditionEZ = value;
+    }
+
+    get conditionNotation() { return this.#conditionNotation; }
+    set conditionNotation(value) {
+        switch (value) {
+            case Constants.VBU.NAMES  :
+            case Constants.VBU.NUMBERS: break;
+            default: return;
+        }
+        this.#conditionNotation = value;
+    }
+
+    get hexCase() { return this.#hexCase; }
+    set hexCase(value) {
+        switch (value) {
+            case Constants.VBU.LOWER:
+            case Constants.VBU.UPPER: break;
+            default: return;
+        }
+        this.#hexCase = value;
+    }
+
+    get hexNotation() { return this.#hexNotation; }
+    set hexNotation(value) {
+        switch (value) {
+            case Constants.VBU["0X"] :
+            case Constants.VBU.DOLLAR:
+            case Constants.VBU.H     : break;
+            default: return;
+        }
+        this.#hexNotation = value;
+    }
+
+    get immediateNotation() { return this.#immediateNotation; }
+    set immediateNotation(value) {
+        switch (value) {
+            case Constants.VBU.NONE  :
+            case Constants.VBU.NUMBER: break;
+            default: return;
+        }
+        this.#immediateNotation = value;
+    }
+
+    get memoryNotation() { return this.#memoryNotation; }
+    set memoryNotation(value) {
+        switch (value) {
+            case Constants.VBU.INSIDE :
+            case Constants.VBU.OUTSIDE: break;
+            default: return;
+        }
+        this.#memoryNotation = value;
+    }
+
+    get mnemonicCase() { return this.#mnemonicCase; }
+    set mnemonicCase(value) {
+        switch (value) {
+            case Constants.VBU.LOWER:
+            case Constants.VBU.UPPER: break;
+            default: return;
+        }
+        this.#mnemonicCase = value;
+    }
+
+    get operandOrder() { return this.#operandOrder; }
+    set operandOrder(value) {
+        switch (value) {
+            case Constants.VBU.DEST_FIRST:
+            case Constants.VBU.DEST_LAST : break;
+            default: return;
+        }
+        this.#operandOrder = value;
+    }
+
+    get programCase() { return this.#programCase; }
+    set programCase(value) {
+        switch (value) {
+            case Constants.VBU.LOWER:
+            case Constants.VBU.UPPER: break;
+            default: return;
+        }
+        this.#programCase = value;
+    }
+
+    get programNotation() { return this.#programNotation; }
+    set programNotation(value) {
+        switch (value) {
+            case Constants.VBU.NAMES  :
+            case Constants.VBU.NUMBERS: break;
+            default: return;
+        }
+        this.#programNotation = value;
+    }
+
+    get setfNotation() { return this.#setfNotation; }
+    set setfNotation(value) {
+        switch (value) {
+            case Constants.VBU.JOINED:
+            case Constants.VBU.SPLIT : break;
+            default: return;
+        }
+        this.#setfNotation = value;
+    }
+
+    get systemCase() { return this.#systemCase; }
+    set systemCase(value) {
+        switch (value) {
+            case Constants.VBU.LOWER:
+            case Constants.VBU.UPPER: break;
+            default: return;
+        }
+        this.#systemCase = value;
+    }
+
+    get systemNotation() { return this.#systemNotation; }
+    set systemNotation(value) {
+        switch (value) {
+            case Constants.VBU.NAMES  :
+            case Constants.VBU.NUMBERS: break;
+            default: return;
+        }
+        this.#systemNotation = value;
+    }
+
+}
+
+
+
+////////////////////////////////// DasmLine ///////////////////////////////////
+
+// One line of disassembler output
+class DasmLine {
+
+    // Instance fields
+    #address;
+    #addressText;
+    #code;
+    #codeText;
+    #isPC;
+    #mnemonicText;
+    #operandText;
+
+
+
+    ///////////////////////// Initialization Methods //////////////////////////
+
+    constructor() {
+        if (arguments[0] != GUARD)
+            throw new Error("Cannot be instantiated.");
+        let line = arguments[1];
+        this.#address      = line.address;
+        this.#addressText  = line.text.address;
+        this.#code         = line.code;
+        this.#codeText     = line.text.code;
+        this.#isPC         = line.isPC;
+        this.#mnemonicText = line.text.mnemonic;
+        this.#operandText  = line.text.operands;
+    }
+
+
+
+    /////////////////////////// Property Accessors ////////////////////////////
+
+    get address() { return this.#address;      }
+    get code   () { return this.#code.slice(); }
+    get isPC   () { return this.#isPC;         }
+    get text   () {
+        return {
+            address : this.#addressText,
+            code    : this.#codeText.slice(),
+            mnemonic: this.#mnemonicText,
+            operands: this.#operandText.slice()
+        };
+    }
+
+
+
+    ///////////////////////////// Public Methods //////////////////////////////
+
+    // Express self as a plain object
+    toObject() {
+        return {
+            address: this.address,
+            code   : Array.from(this.#code),
+            isPC   : this.isPC,
+            text   : this.text
+        };
+    }
+
+}
+
+
+
+///////////////////////////////////// Sim /////////////////////////////////////
+
+// Simulation instance
+class Sim extends HTMLElement {
+
+    // Instance fields
+    #anaglyph;  // Anaglyph color values
+    #canvas;    // Canvas element
+    #core;      // Core proxy
+    #emulating; // Current emulation status
+    #keys;      // Controller state
+    #panning;   // Audio stereo balance
+    #peer;      // Communication peer
+    #pointer;   // Pointer in core memory
+    #volume;    // Audio output volume
+
+
+
+    ///////////////////////// Initialization Methods //////////////////////////
+
+    constructor() {
+        if (arguments[0] != GUARD)
+            throw new Error("Must be created via VB.create()");
+        super();
+        this.proxy = {
+            construct   : (core, pointer)=>this.#construct(core, pointer),
+            isEmulating : ()=>this.#emulating,
+            setEmulating: e =>this.#emulating = e,
+            setPeer     : p =>this.#peer      = p
+        };
+    }
+
+    // Asynchronous constructor
+    async #construct(core, pointer) {
+
+        // Configure instance fields
+        this.#anaglyph  = [ VB.STEREO_RED, VB.STEREO_CYAN ];
+        this.#core      = core;
+        this.#emulating = false;
+        this.#keys      = Constants.VB.SGN;
+        this.#panning   = 0.0;
+        this.#peer      = null;
+        this.#pointer   = pointer;
+        this.#volume    = 1.0;
+        delete this.proxy;
+
+        // Create a <canvas> for the video image
+        let canvas = this.#canvas = document.createElement("canvas");
+        Object.assign(canvas, { width: 384, height: 224 });
+        canvas.style.imageRendering = "pixelated";
+
+        // Configure elements
+        Object.assign(this.style, {
+            display : "inline-block",
+            height  : "224px",
+            position: "relative",
+            width   : "384px"
+        });
+        Object.assign(canvas.style, {
+            height        : "100%",
+            imageRendering: "pixelated",
+            left          : "0",
+            position      : "absolute",
+            top           : "0",
+            width         : "100%"
+        });
+        this.append(canvas);
+
+        // Send control of the canvas to the core worker
+        let offscreen = canvas.transferControlToOffscreen();
+        await core.toCore({
+            command  : "setCanvas",
+            promised : true,
+            sim      : pointer,
+            canvas   : offscreen,
+            transfers: [ offscreen ]
+        });
+
+        return this;
+    }
+
+
+
+    /////////////////////////// Property Accessors ////////////////////////////
+
+    get anaglyph() { return this.#anaglyph.slice(); }
+    get core    () { return this.#core.core       ; }
+    get keys    () { return this.#keys            ; }
+    get panning () { return this.#panning         ; }
+    get peer    () { return this.#peer            ; }
+    get volume  () { return this.#volume          ; }
+
+
+
+    ///////////////////////////// Public Methods //////////////////////////////
+
+    // Delete the sim
+    async delete() {
+        // Unlink peer
+        // Deallocate memory
+        // Unlink core
+    }
+
+    // Disassemble from a simulation
+    async disassemble(address, config, length, line) {
+
+        // Error checking
+        if (!Number.isSafeInteger(address) ||
+            address < 0 || address > 0xFFFFFFFF)
+            throw new RangeError("Address must conform to Uint32.");
+        if (config != null && !(config instanceof DasmConfig))
+            throw new TypeError("Config must be an instance of DasmConfig.");
+        if (!Number.isSafeInteger(address) || length < 0)
+            throw new RangeError("Length must be nonnegative.");
+        if (!Number.isSafeInteger(line))
+            throw new TypeError("Line must be a safe integer.");
+
+        // Request disassembly from the core
+        let response = await this.#core.toCore({
+            command : "disassemble",
+            promised: true,
+            sim     : this.#pointer,
+            address : address,
+            length  : length,
+            line    : line,
+            config  : config == null ? null : {
+                bcondNotation    : config.bcondNotation,
+                conditionCase    : config.conditionCase,
+                conditionCL      : config.conditionCL,
+                conditionEZ      : config.conditionEZ,
+                conditionNotation: config.conditionNotation,
+                hexCase          : config.hexCase,
+                hexNotation      : config.hexNotation,
+                immediateNotation: config.immediateNotation,
+                memoryNotation   : config.memoryNotation,
+                mnemonicCase     : config.mnemonicCase,
+                operandOrder     : config.operandOrder,
+                programCase      : config.programCase,
+                programNotation  : config.programNotation,
+                setfNotation     : config.setfNotation,
+                systemCase       : config.systemCase,
+                systemNotation   : config.systemNotation
+            }
+        });
+
+        // Process the response
+        return !response.success ? null :
+            response.lines.map(l=>new DasmLine(GUARD, l));
+    }
+
+    // Reset simulation state
+    reset() {
+        return this.#core.toCore({
+            command : "reset",
+            promised: true,
+            sim     : this.#pointer
+        });
+    }
+
+    // Specify anaglyph colors
+    setAnaglyph(left, right) {
+
+        // Error checking
+        if (!Number.isSafeInteger(left ) || left  < 0 || left  > 0xFFFFFF)
+            throw new RangeError("Left must conform to Uint24.");
+        if (!Number.isSafeInteger(right) || right < 0 || right > 0xFFFFFF)
+            throw new RangeError("Right must conform to Uint24.");
+        if (
+            left & 0xFF0000 && right & 0xFF0000 ||
+            left & 0x00FF00 && right & 0x00FF00 ||
+            left & 0x0000FF && right & 0x0000FF
+        ) throw new RangeError("Left and right overlap RGB channels.");
+
+        // Configure instance fields
+        this.#anaglyph[0] = left;
+        this.#anaglyph[1] = right;
+
+        // Send the colors to the core
+        return this.#core.toCore({
+            command : "setAnaglyph",
+            promised: true,
+            sim     : this.#pointer,
+            left    : left,
+            right   : right
+        });
+    }
+
+    // Specify a game pak RAM buffer
+    setCartRAM(wram) {
+        return this.#setCartMemory("setCartRAM", wram);
+    }
+
+    // Specify a game pak ROM buffer
+    setCartROM(rom) {
+        return this.#setCartMemory("setCartROM", rom);
+    }
+
+    // Specify new game pad keys
+    setKeys(keys) {
+
+        // Error checking
+        if (!Number.isSafeInteger(keys) || keys < 0 || keys > 0xFFFF)
+            throw new RangeError("Keys must conform to Uint16.");
+        if (keys == this.#keys)
+            return;
+
+        // Configure instance fields
+        this.#keys = keys;
+
+        // Send the keys to the core
+        return this.#core.toCore({
+            command : "setKeys",
+            promised: true,
+            sim     : this.#pointer,
+            keys    : keys
+        });
+    }
+
+    // Specify audio panning
+    setPanning(panning) {
+
+        // Error checking
+        if (!Number.isFinite(panning) ||panning < -1 || panning > +1) {
+            throw new RangeError(
+                "Panning must be a number from -1 to +1.");
+        }
+
+        // Configure instance fields
+        this.#panning = panning;
+
+        // Send the panning to the core
+        return this.#core.toCore({
+            command : "setPanning",
+            promised: true,
+            sim     : this.#pointer,
+            panning : panning
+        });
+    }
+
+    // Specify a new communication peer
+    async setPeer(peer = null) {
+
+        // Error checking
+        if (peer !== null && peer.#core != this.#core)
+            throw new RangeError("Peer sim must belong to the same core.");
+
+        // Configure peers on the core
+        if (peer != this.#peer)
+            await this.#core.setPeer(this, peer);
+    }
+
+    // Specify audio volume
+    setVolume(volume) {
+
+        // Error checking
+        if (!Number.isFinite(volume) ||volume < 0 || volume > 10) {
+            throw new RangeError(
+                "Volume must be a number from 0\u00d7 to 10\u00d7.");
+        }
+
+        // Configure instance fields
+        this.#volume = volume;
+
+        // Send the volume to the core
+        return this.#core.toCore({
+            command : "setVolume",
+            promised: true,
+            sim     : this.#pointer,
+            volume  : volume
+        });
+    }
+
+
+
+    ///////////////////////////// Private Methods /////////////////////////////
+
+    // Specify a game pak memory buffer
+    async #setCartMemory(command, mem) {
+
+        // Validation
+        if (mem instanceof ArrayBuffer)
+            mem = new Uint8Array(mem);
+        if (
+            !(mem instanceof Uint8Array) &&
+            !(mem instanceof Uint8ClampedArray)
+        ) mem = Uint8Array.from(mem);
+
+        // Send the memory to the core
+        let response = await this.#core.toCore({
+            command  : command,
+            promised : true,
+            sim      : this.#pointer,
+            data     : mem.buffer,
+            transfers: [ mem.buffer ]
+        });
+        return response.success;
+    }
+
+}
+customElements.define("shrooms-vb", Sim);
+
+
+
+///////////////////////////////////// VB //////////////////////////////////////
+
+// Emulation core interface
+class VB {
+
+    // Static fields
+    static get DasmConfig() { return DasmConfig; }
+    static get DasmLine  () { return DasmLine;   }
+    static get Sim       () { return Sim;        }
+
+    // Instance fields
+    #audio;     // Audio worklet
+    #automatic; // Current automatic emulation group
+    #commands;  // Computed method table
+    #core;      // Core worker
+    #proxy;     // Self proxy for sim access
+    #sims;      // Mapping of Sim|pointer -> proxy
+    #state;     // Operations state
+
+
+
+    //////////////////////////////// Constants ////////////////////////////////
+
+    // Operations states
+    static #SUSPENDED  = Symbol();
+    static #RESUMING   = Symbol();
+    static #EMULATING  = Symbol();
+    static #SUSPENDING = Symbol();
+
+    // System registers
+    static get ADTRE() { return Constants.VB.ADTRE; }
+    static get CHCW () { return Constants.VB.CHCW ; }
+    static get ECR  () { return Constants.VB.ECR  ; }
+    static get EIPC () { return Constants.VB.EIPC ; }
+    static get EIPSW() { return Constants.VB.EIPSW; }
+    static get FEPC () { return Constants.VB.FEPC ; }
+    static get FEPSW() { return Constants.VB.FEPSW; }
+    static get PIR  () { return Constants.VB.PIR  ; }
+    static get PSW  () { return Constants.VB.PSW  ; }
+    static get TKCW () { return Constants.VB.TKCW ; }
+
+    // Memory access data types
+    static get S8 () { return Constants.VB.S8 ; }
+    static get U8 () { return Constants.VB.U8 ; }
+    static get S16() { return Constants.VB.S16; }
+    static get U16() { return Constants.VB.U16; }
+    static get S32() { return Constants.VB.S32; }
+
+    // Option keys
+    static get PSEUDO_HALT() { return Constants.VB.PSEUDO_HALT; }
+
+    // Controller buttons
+    static get PWR() { return Constants.VB.PWR; }
+    static get SGN() { return Constants.VB.SGN; }
+    static get A  () { return Constants.VB.A  ; }
+    static get B  () { return Constants.VB.B  ; }
+    static get RT () { return Constants.VB.RT ; }
+    static get LT () { return Constants.VB.LT ; }
+    static get RU () { return Constants.VB.RU ; }
+    static get RR () { return Constants.VB.RR ; }
+    static get LR () { return Constants.VB.LR ; }
+    static get LL () { return Constants.VB.LL ; }
+    static get LD () { return Constants.VB.LD ; }
+    static get LU () { return Constants.VB.LU ; }
+    static get STA() { return Constants.VB.STA; }
+    static get SEL() { return Constants.VB.SEL; }
+    static get RL () { return Constants.VB.RL ; }
+    static get RD () { return Constants.VB.RD ; }
+
+    // Disassembler options
+    static get ["0X"]    () { return Constants.VBU["0X"]     ; }
+    static get ABSOLUTE  () { return Constants.VBU.ABSOLUTE  ; }
+    static get C         () { return Constants.VBU.C         ; }
+    static get DEST_FIRST() { return Constants.VBU.DEST_FIRST; }
+    static get DEST_LAST () { return Constants.VBU.DEST_LAST ; }
+    static get DOLLAR    () { return Constants.VBU.DOLLAR    ; }
+    static get E         () { return Constants.VBU.E         ; }
+    static get H         () { return Constants.VBU.H         ; }
+    static get INSIDE    () { return Constants.VBU.INSIDE    ; }
+    static get JOINED    () { return Constants.VBU.JOINED    ; }
+    static get L         () { return Constants.VBU.L         ; }
+    static get LOWER     () { return Constants.VBU.LOWER     ; }
+    static get NAMES     () { return Constants.VBU.NAMES     ; }
+    static get NONE      () { return Constants.VBU.NONE      ; }
+    static get NUMBER    () { return Constants.VBU.NUMBER    ; }
+    static get NUMBERS   () { return Constants.VBU.NUMBERS   ; }
+    static get OUTSIDE   () { return Constants.VBU.OUTSIDE   ; }
+    static get RELATIVE  () { return Constants.VBU.RELATIVE  ; }
+    static get SPLIT     () { return Constants.VBU.SPLIT     ; }
+    static get UPPER     () { return Constants.VBU.UPPER     ; }
+    static get Z         () { return Constants.VBU.Z         ; }
+
+    // Anaglyph colors
+    static get STEREO_CYAN   () { return Constants.web.STEREO_CYAN   ; }
+    static get STEREO_GREEN  () { return Constants.web.STEREO_GREEN  ; }
+    static get STEREO_MAGENTA() { return Constants.web.STEREO_MAGENTA; }
+    static get STEREO_RED    () { return Constants.web.STEREO_RED    ; }
+
+
+
+    ///////////////////////////// Static Methods //////////////////////////////
+
+    // Create a core instance
+    static create(options) {
+        return new VB(GUARD).#construct(options);
+    }
+
+
+
+    ///////////////////////// Initialization Methods //////////////////////////
+
+    constructor() {
+        if (arguments[0] != GUARD)
+            throw new Error("Must be created via VB.create()");
+    }
+
+    // Asynchronous constructor
+    async #construct(options) {
+
+        // Configure instance fields
+        this.#automatic = null;
+        this.#sims      = new Map();
+        this.#state     = VB.#SUSPENDED;
+
+        // Ensure default options
+        options          ??= {};
+        options.audioUrl ??= import.meta.resolve("./Audio.js");
+        options.coreUrl  ??= import.meta.resolve("./Core.js");
+        options.wasmUrl  ??= import.meta.resolve("./core.wasm");
+
+        // Core<->audio communications
+        let channel = new MessageChannel();
+
+        // Audio output context
+        let audio = new AudioContext({
+            latencyHint: "interactive",
+            sampleRate : 41700
+        });
+        await audio.suspend();
+
+        // Audio node
+        await audio.audioWorklet.addModule(options.audioUrl);
+        audio = this.#audio = new AudioWorkletNode(audio, "shrooms-vb", {
+            numberOfInputs    :  0,
+            numberOfOutputs   :  1,
+            outputChannelCount: [2]
+        });
+        audio.connect(audio.context.destination);
+
+        // Send one message channel port to the audio worklet
+        await new Promise(resolve=>{
+            audio.port.onmessage = resolve;
+            audio.port.postMessage({
+                core: channel.port1
+            }, [channel.port1]);
+        });
+        audio.port.onmessage = null;//e=>this.#onAudio(e.data);
+
+        // Core worker
+        let core = this.#core = new Worker(options.coreUrl, {type: "module"});
+        core.promises = [];
+
+        // Send the other message channel port to the core worker
+        await new Promise(resolve=>{
+            core.onmessage = resolve;
+            core.postMessage({
+                audio  : channel.port2,
+                wasmUrl: options.wasmUrl
+            }, [ channel.port2 ]);
+        });
+        core.onmessage = e=>this.#onCore(e.data);
+
+        // Establish a concealed proxy for sim objects
+        this.#proxy = {
+            core   : this,
+            setPeer: (a,b)=>this.#setPeer(a,b),
+            toCore : m=>this.#toCore(m)
+        };
+
+        // Configure command table
+        this.#commands = {
+            // Will be used with subscriptions
+        };
+
+        return this;
+    }
+
+
+
+    /////////////////////////////// Properties ////////////////////////////////
+
+    // Number of managed simulations
+    get size() { return this.#sims.size / 2; }
+
+    // Managed simulations
+    get sims() { return [... this.#sims.keys()].filter(s=>s instanceof Sim); }
+
+
+
+    ///////////////////////////// Public Methods //////////////////////////////
+
+    // Create one or more sims
+    async create(count = null) {
+
+        // Error checking
+        if (count !== null && (!Number.isSafeInteger(count) || count < 1)) {
+            throw new RangeError(
+                "Count must be a safe integer and at least 1.");
+        }
+
+        // Allocate memory in the core
+        let response = await this.#toCore({
+            command : "createSims",
+            promised: true,
+            count   : count ?? 1
+        });
+
+        // Produce Sim elements for each instance
+        let sims = response.sims;
+        for (let x = 0; x < (count ?? 1); x++) {
+            let proxy = new Sim(GUARD).proxy;
+            proxy.pointer = sims[x];
+            proxy.sim     = sims[x] =
+                await proxy.construct(this.#proxy, sims[x]);
+            this.#sims.set(sims[x], proxy);
+            this.#sims.set(proxy.pointer, proxy);
+        }
+        return count === null ? sims[0] : sims;
+    }
+
+    // Begin emulation
+    async emulate(sims, clocks) {
+
+        // Error checking
+        if (sims instanceof Sim)
+            sims = [sims];
+        if (
+            !Array.isArray(sims) ||
+            sims.length == 0     ||
+            sims.some(s=>!this.#sims.has(s))
+        ) {
+            throw new TypeError("Must specify a Sim or array of Sims " +
+                "that belong to this core.");
+        }
+        if (sims.find(s=>this.#sims.get(s).isEmulating()))
+            throw new Error("Sims cannot already be part of emulation.");
+        if (
+            clocks !== true &&
+            !(Number.isSafeInteger(clocks) && clocks >= 0)
+        ) {
+            throw new RangeError(
+                "Clocks must be true or a nonnegative safe integer.");
+        }
+
+        // Cannot resume automatic emulation
+        if (clocks === true && this.#state != VB.#SUSPENDED)
+            return false;
+
+        // Manage sims
+        let proxies  = sims   .map(s=>this.#sims.get(s));
+        let pointers = proxies.map(p=>p.pointer);
+        for (let sim of proxies)
+            sim.setEmulating(true);
+
+        // Clocked emulation
+        if (clocks !== true) {
+            let response = await this.#toCore({
+                command : "emulateClocked",
+                promised: true,
+                sims    : pointers,
+                clocks  : clocks
+            });
+            for (let sim of proxies)
+                sim.setEmulating(false);
+            return {
+                broke : response.broke,
+                clocks: response.clocks
+            };
+        }
+
+        // Resume automatic emulation
+        this.#automatic = proxies;
+        this.#state     = VB.#RESUMING;
+        if (this.#audio.context.state == "suspended")
+            await this.#audio.context.resume();
+        await this.#toCore({
+            command : "emulateAutomatic",
+            promised: true,
+            sims    : pointers
+        });
+        this.#state = VB.#EMULATING;
+        return true;
+    }
+
+    // Decode an ISX debugger file to a Virtual Boy ROM
+    async fromISX(data) {
+
+        // Validation
+        if (data instanceof ArrayBuffer)
+            data = new Uint8Array(data);
+        if (
+            !(data instanceof Uint8Array) &&
+            !(data instanceof Uint8ClampedArray)
+        ) data = Uint8Array.from(data);
+
+        // Send the memory to the core
+        data = data.slice();
+        let response = await this.#toCore({
+            command  : "fromISX",
+            promised : true,
+            data     : data.buffer,
+            transfers: [ data.buffer ]
+        });
+        return response.data == null ? null : new Uint8Array(response.data);
+    }
+
+    // Suspend automatic emulation
+    async suspend() {
+
+        // Error checking
+        if (this.#state != VB.#EMULATING)
+            return false;
+
+        // Tell the core to stop emulating
+        this.#state = VB.#SUSPENDING;
+        await this.#toCore({
+            command : "suspend",
+            promised: true
+        });
+
+        // Configure state
+        this.#state = VB.#SUSPENDED;
+        for (let sim of this.#automatic)
+            sim.setEmulating(false);
+        return true;
+    }
+
+
+
+    ///////////////////////////// Private Methods /////////////////////////////
+
+    // Message received from core worker
+    #onCore(message) {
+        if (message.promised)
+            this.#core.promises.shift()(message);
+        if ("command" in message)
+            this.#commands[message.command](message);
+    }
+
+    // Specify a new communication peer
+    async #setPeer(sim, peer) {
+
+        // Associate the peers on the core
+        let response = await this.#toCore({
+            command : "setPeer",
+            promised: true,
+            sim     : this.#sims.get(sim).pointer,
+            peer    : peer == null ? 0 : this.#sims.get(peer).pointer
+        });
+
+        // Link sims
+        this.#sims.get(sim).setPeer(peer);
+        if (peer != null)
+            this.#sims.get(peer).setPeer(sim);
+
+        // Unlink orphaned sims
+        for (let pointer of response.orphaned)
+            this.#sims.get(pointer).setPeer(null);
+    }
+
+    // Send a message to the core worker
+    async #toCore(message) {
+        let transfers = message.transfers;
+        if (transfers != null)
+            delete message.transfers;
+        return await new Promise(resolve=>{
+            if (message.promised)
+                this.#core.promises.push(resolve);
+            this.#core.postMessage(message, transfers ?? []);
+        });
+    }
+
+}
+
+export default VB;

web/wasm.c

@@ -0,0 +1,273 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <emscripten/emscripten.h>
+#include <vb.h>
+#include <vbu.h>
+
+
+
+////////////////////////////////// Constants //////////////////////////////////
+
+// Break conditions
+#define BREAK_FRAME 1
+#define BREAK_POINT 2
+
+// Anaglyph colors
+#define STEREO_CYAN    0x00C6F0
+#define STEREO_GREEN   0x00B400
+#define STEREO_MAGENTA 0xC800FF
+#define STEREO_RED     0xFF0000
+
+// Element counts
+#define NUM_SAMPLES (41700 / 50 * 2)
+
+
+
+//////////////////////////////////// Types ////////////////////////////////////
+
+// Additional monitor state for simulations
+typedef struct {
+    int32_t  breaks;
+    uint32_t left[256];
+    float    panning;
+    uint8_t  pixels[384 * 224 * 4];
+    uint32_t right[256];
+    float    samples[NUM_SAMPLES];
+    float    volume;
+} Ext;
+
+
+
+////////////////////////////////// Callbacks //////////////////////////////////
+
+// Frame callback
+int wasmOnFrame(VB *sim) {
+    ((Ext *) vbGetUserData(sim))->breaks |= BREAK_FRAME;
+    return 1;
+}
+
+
+
+/////////////////////////////// Module Exports ////////////////////////////////
+
+// Specify anaglyph colors
+EMSCRIPTEN_KEEPALIVE void SetAnaglyph(VB *sim, uint32_t left, uint32_t right) {
+    Ext *ext = (Ext *) vbGetUserData(sim);
+
+    // Erase all RGB values
+    for (int x = 0; x < 256; x++)
+        ext->left[x] = ext->right[x] = 0xFF000000;
+
+    // Process all RGB channels
+    for (int c = 0, shift = 16; c < 3; c++, shift -= 8) {
+        double    max;  // Magnitude of channel value
+        uint32_t *dest; // Lookup data
+
+        // Select the magnitude and lookup channel
+        dest = ext->left;
+        max  = (left >> shift & 0xFF) / 255.0;
+        if (max == 0) {
+            dest = ext->right;
+            max  = (right >> shift & 0xFF) / 255.0;
+            if (max == 0)
+                continue;
+        }
+
+        // Compute the resulting RGB values
+        for (int x = 0; x < 256; x++)
+            *dest++ |= (uint32_t) (x * max + 0.5) << (16 - shift);
+    }
+
+}
+
+// Instantiate a simulation
+EMSCRIPTEN_KEEPALIVE void* CreateSim() {
+    size_t   sizeOfSim = vbSizeOf();
+    uint8_t *pointer   = malloc(sizeOfSim + sizeof (Ext));
+
+    // Configure sim
+    VB *sim = vbInit((VB *) pointer);
+    vbSetFrameCallback(sim, &wasmOnFrame);
+    vbSetOption(sim, VB_PSEUDO_HALT, 1);
+
+    // Configure extra
+    Ext *ext = (Ext *) (pointer + sizeOfSim);
+    ext->breaks  = 0;
+    ext->panning = 0.0f;
+    ext->volume  = 1.0f;
+    vbSetUserData(sim, ext);
+    SetAnaglyph(sim, STEREO_RED, STEREO_CYAN);
+
+    // Initialize pixels with opaque black
+    for (unsigned x = 0; x < 384 * 224; x++)
+        ((uint32_t *) ext->pixels)[x] = 0xFF000000;
+
+    return sim;
+}
+
+// Disassemble from a simulation
+EMSCRIPTEN_KEEPALIVE void* Disassemble(
+    int bcondNotation, int conditionCase, int conditionCL, int conditionEZ,
+    int conditionNotation, int hexCase, int hexNotation, int immediateNotation,
+    int memoryNotation, int mnemonicCase, int operandOrder, int programCase,
+    int programNotation, int setfNotation, int systemCase, int systemNotation,
+    VB *sim, uint32_t address, unsigned length, int line
+) {
+    VBU_DasmConfig config;
+    config.bcondNotation     = bcondNotation;
+    config.conditionCase     = conditionCase;
+    config.conditionCL       = conditionCL;
+    config.conditionEZ       = conditionEZ;
+    config.conditionNotation = conditionNotation;
+    config.hexCase           = hexCase;
+    config.hexNotation       = hexNotation;
+    config.immediateNotation = immediateNotation;
+    config.memoryNotation    = memoryNotation;
+    config.mnemonicCase      = mnemonicCase;
+    config.operandOrder      = operandOrder;
+    config.programCase       = programCase;
+    config.programNotation   = programNotation;
+    config.setfNotation      = setfNotation;
+    config.systemCase        = systemCase;
+    config.systemNotation    = systemNotation;
+    return vbuDisassemble(sim, address, &config, length, line);
+}
+
+// Process simulations
+EMSCRIPTEN_KEEPALIVE int Emulate(VB **sims, unsigned count, uint32_t *clocks) {
+    for (unsigned x = 0; x < count; x++)
+        ((Ext *) vbGetUserData(sims[x]))->breaks = 0;
+    return vbEmulateEx(sims, count, clocks);
+}
+
+// Retrieve a sim's pixel pointer
+EMSCRIPTEN_KEEPALIVE void* GetExtPixels(VB *sim) {
+    return ((Ext *) vbGetUserData(sim))->pixels;
+}
+
+// Retrieve a sim's sample pointer
+EMSCRIPTEN_KEEPALIVE void* GetExtSamples(VB *sim) {
+    return ((Ext *) vbGetUserData(sim))->samples;
+}
+
+// Retrieve the break condition flags for a sim
+EMSCRIPTEN_KEEPALIVE int32_t GetBreaks(VB *sim) {
+    return ((Ext *) vbGetUserData(sim))->breaks;
+}
+
+// Serialize disassembled lines into a linear buffer
+EMSCRIPTEN_KEEPALIVE void GetDasm(uint32_t *buffer, void *dasm, int count) {
+    for (int x = 0; x < count; x++) {
+        VBU_DasmLine *line = &((VBU_DasmLine *) dasm)[x];
+
+        // Numeric data
+        *buffer++ = line->address;
+        *buffer++ = line->codeLength;
+        for (int y = 0; y < 4; y++)
+            *buffer++ = line->code[y];
+        *buffer++ = line->isPC;
+
+        // Text data -- Store offset of string pointer from start of dasm
+        *buffer++ = (uint32_t) ((void *) &line->text.address - dasm);
+        for (int y = 0; y < 4; y++)
+            *buffer++ = (uint32_t) ((void *) &line->text.code[y] - dasm);
+        *buffer++ = (uint32_t) ((void *) &line->text.mnemonic - dasm);
+        *buffer++ = line->text.operandsLength;
+        for (int y = 0; y < 3; y++)
+            *buffer++ = (uint32_t) ((void *) &line->text.operands[y] - dasm);
+    }
+}
+
+// Retrieve anaglyph-tinted pixels from a sim
+EMSCRIPTEN_KEEPALIVE void GetPixels(VB *sim) {
+    Ext     *ext    = (Ext *) vbGetUserData(sim);
+    uint8_t *pixels = ext->pixels;
+    vbGetPixels(sim, pixels, 4, 384 * 4, pixels + 1, 4, 384 * 4);
+    for (unsigned x = 0; x < 384 * 224 * 4; x += 4, pixels += 4)
+        *(uint32_t *) pixels = ext->left[pixels[0]] | ext->right[pixels[1]];
+}
+
+// Mix audio samples for output
+EMSCRIPTEN_KEEPALIVE void Mix(float *buffer, VB **sims, int count) {
+
+    // Process all sims
+    for (int x = 0; x < count; x++) {
+        Ext   *ext     = (Ext *) vbGetUserData(sims[x]);
+        float *samples = ext->samples;
+        float  v       = ext->volume;
+
+        // First sim initializes buffer
+        if (x == 0) {
+            if (ext->panning < 0) {
+                float l = -ext->panning * v;
+                float r = (1.0f + ext->panning) * v;
+                for (unsigned y = 0; y < NUM_SAMPLES; y += 2) {
+                    buffer[y    ] = samples[y] * v + samples[y + 1] * l;
+                    buffer[y + 1] = samples[y + 1] * r;
+                }
+            } else if (ext->panning > 0) {
+                float r = ext->panning * v;
+                float l = (1.0f - ext->panning) * v;
+                for (unsigned y = 0; y < NUM_SAMPLES; y += 2) {
+                    buffer[y    ] = samples[y] * l;
+                    buffer[y + 1] = samples[y + 1] * v + samples[y] * r;
+                }
+            } else {
+                for (unsigned y = 0; y < NUM_SAMPLES; y++)
+                    buffer[y] = samples[y] * v;
+            }
+        }
+
+        // Subsequent sims add to buffer
+        else {
+            if (ext->panning < 0) {
+                float l = -ext->panning * v;
+                float r = (1.0f + ext->panning) * v;
+                for (unsigned y = 0; y < NUM_SAMPLES; y += 2) {
+                    buffer[y    ] += samples[y] * v + samples[y + 1] * l;
+                    buffer[y + 1] += samples[y + 1] * r;
+                }
+            } else if (ext->panning > 0) {
+                float r = ext->panning * v;
+                float l = (1.0f - ext->panning) * v;
+                for (unsigned y = 0; y < NUM_SAMPLES; y += 2) {
+                    buffer[y    ] += samples[y] * l;
+                    buffer[y + 1] += samples[y + 1] * v + samples[y] * r;
+                }
+            } else {
+                for (unsigned y = 0; y < NUM_SAMPLES; y++)
+                    buffer[y] += samples[y] * v;
+            }
+        }
+
+    }
+
+    // Clipping
+    for (unsigned y = 0; y < NUM_SAMPLES; y++) {
+        if (buffer[y] < -1.0f)
+            buffer[y] = -1.0f;
+        else if (buffer[y] > +1.0f)
+            buffer[y] = +1.0f;
+    }
+
+}
+
+// Determine the size in bytes of a pointer
+EMSCRIPTEN_KEEPALIVE int PointerSize() {
+    return sizeof (void *);
+}
+
+// Memory management
+EMSCRIPTEN_KEEPALIVE void* Realloc(void *data, size_t size) {
+    return realloc(data, size);
+}
+
+// Specify audio panning
+EMSCRIPTEN_KEEPALIVE void SetPanning(VB *sim, float panning) {
+    ((Ext *) vbGetUserData(sim))->panning = panning;
+}
+
+// Specify audio volume
+EMSCRIPTEN_KEEPALIVE void SetVolume(VB *sim, float volume) {
+    ((Ext *) vbGetUserData(sim))->volume = volume;
+}