Adjust brightness values

Reviewed-on: #1

core/bus.c

@@ -159,6 +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

@@ -234,7 +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);
@@ -289,7 +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)
@@ -495,7 +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 */
@@ -1637,6 +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/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

@@ -29,6 +29,7 @@ typedef struct {
 
         /* Other state */
         uint32_t clocks;  /* Clocks until modification */
+        uint8_t  modmask; /* Modifications masked */
         uint8_t  reload;  /* Automatic reload value */
     } env;
 
@@ -251,6 +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;
 
@@ -311,6 +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;
 
@@ -325,6 +328,7 @@ 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 */
@@ -357,6 +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;
@@ -631,7 +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++;
@@ -894,7 +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

@@ -126,7 +126,6 @@ typedef int  (*vbOnWrite    )(VB *sim, uint32_t address, int type, int32_t *valu
 
 VBAPI int           vbEmulate             (VB *sim, 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);
@@ -167,7 +166,7 @@ VBAPI vbOnSamples   vbSetSamplesCallback  (VB *sim, vbOnSamples callback);
 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/vip.c

@@ -41,15 +41,17 @@ static const uint8_t BG_TEMPLATES[][64] = {
 };
 
 /* 8-bit color magnitude by brightness level */
+/* Generated as BRIGHT8[n] = round((n / 132) ** 1.6 * 255) */
 static const uint8_t BRIGHT8[] = {
-      0,  2,  4,  6,  8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30,
+      0, 12, 19, 24, 29, 33, 37, 41, 44, 48, 51, 54, 57, 60, 63, 65,
-     32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62,
+     68, 71, 73, 76, 78, 81, 83, 86, 88, 90, 92, 95, 97, 99,101,103,
-     64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94,
+    105,107,109,111,113,115,117,119,121,123,125,127,128,130,132,134,
-     96, 98,100,102,104,106,108,110,112,114,116,118,120,122,124,126,
+    136,137,139,141,142,144,146,148,149,151,153,154,156,157,159,161,
-    129,131,133,135,137,139,141,143,145,147,149,151,153,155,157,159,
+    162,164,165,167,168,170,172,173,175,176,178,179,181,182,184,185,
-    161,163,165,167,169,171,173,175,177,179,181,183,185,187,189,191,
+    186,188,189,191,192,194,195,197,198,199,201,202,203,205,206,208,
-    193,195,197,199,201,203,205,207,209,211,213,215,217,219,221,223,
+    209,210,212,213,214,216,217,218,220,221,222,224,225,226,228,229,
-    225,227,229,231,233,235,237,239,241,243,245,247,249,251,253,255
+    230,231,233,234,235,236,238,239,240,242,243,244,245,246,248,249,
+    250,251,253,254,255
 };
 
 
@@ -234,7 +236,7 @@ static void vipWriteCell(VB *sim, uint32_t offset, int type, int32_t value) {
         case VB_S8:
         case VB_U8:
             value = offset & 1 ?
-                value << 8 |           sim->vip.ram[0x20000 | offset] :
+                value << 8 |           sim->vip.ram[0x20001 ^ offset] :
                 value      | (int32_t) sim->vip.ram[0x20001 | offset] << 8
             ;
             break;
@@ -284,7 +286,7 @@ static void vipWriteObject(VB *sim, uint32_t offset, int type, int32_t value) {
         case VB_S8:
         case VB_U8:
             value = offset & 1 ?
-                value << 8 |           sim->vip.ram[0x3E000 | offset] :
+                value << 8 |           sim->vip.ram[0x3E001 ^ offset] :
                 value      | (int32_t) sim->vip.ram[0x3E001 | offset] << 8
             ;
             break;
@@ -326,7 +328,7 @@ static void vipWriteWorld(VB *sim, uint32_t offset, int type, int32_t value) {
         case VB_S8:
         case VB_U8:
             value = offset & 1 ?
-                value << 8 |           sim->vip.ram[0x3D800 | offset] :
+                value << 8 |           sim->vip.ram[0x3D801 ^ offset] :
                 value      | (int32_t) sim->vip.ram[0x3D801 | offset] << 8
             ;
             break;
@@ -435,6 +437,9 @@ static void vipWriteIO(
 
         case 0x5F802>>1: /* INTENB */
             sim->vip.intenb = (sim->vip.intenb & mask) | (value & 0xE01F);
+            if (sim->vip.intenb & sim->vip.intpnd)
+                sim->cpu.irq  |=  0x0010;
+            else sim->cpu.irq &= ~0x0010;
             break;
         case 0x5F804>>1: /* INTCLR */
             sim->vip.intpnd &= ~value;
@@ -481,10 +486,12 @@ static void vipWriteIO(
             break;
 
         case 0x5F830>>1: /* CTA */
+            if (debug) {
                 if ((mask & 0xFF00) == 0)
                     sim->vip.cta.cta_r = value >> 8;
                 if ((mask & 0x00FF) == 0)
                     sim->vip.cta.cta_l = value;
+            }
             break;
 
         case 0x5F842>>1: /* XPCTRL */
@@ -544,7 +551,7 @@ static void vipWriteIO(
             break;
 
         case 0x5F870>>1: /* BKCOL */
-            sim->vip.bkcol = (sim->vip.bkcol & mask) | (value & 3 * ~mask);
+            sim->vip.bkcol = (sim->vip.bkcol & mask) | (value & 3 & ~mask);
             break;
     }
 
@@ -584,7 +591,7 @@ static void vipComputeBrightness(VB *sim) {
 
     /* Transform brightness values to 0..255 */
     for (x = 1; x < 4; x++)
-        sim->vip.dp.brt[x] = brt[x] > 127 ? 255 : BRIGHT8[brt[x]];
+        sim->vip.dp.brt[x] = brt[x] > 132 ? 255 : BRIGHT8[brt[x]];
 }
 
 /* Transfer one column of frame buffer pixels to output */
@@ -596,7 +603,7 @@ static void vipTransferColumn(VB *sim, int32_t eye) {
 
     /* Select destination address in host memory */
     dest = &sim->vip.output
-        [sim->vip.dp.buffer][eye][sim->vip.dp.column];
+        [sim->vip.buffer ^ 1][eye][sim->vip.dp.column];
 
     /* Output is disabled */
     if (!sim->vip.dp.enabled) {
@@ -652,28 +659,29 @@ static int vipEmulateDisplay(VB *sim, uint32_t clocks) {
                 vipThrow(sim, 0x0010); /* FRAMESTART */
 
                 /* Game frame */
-                if (sim->vip.xp.xpen) {
                 if (sim->vip.xp.frame >= sim->vip.frmcyc) {
                     sim->vip.xp.frame = 0;
 
-                        /* Initiate drawing procedure */
-                        if (sim->vip.xp.step == 0) {
-                            sim->vip.dp.buffer  ^= 1;
-                            sim->vip.xp.enabled  = 1;
-                            sim->vip.xp.overtime = 0;
-                            sim->vip.xp.step     = 1;
                     vipThrow(sim, 0x0008); /* GAMESTART */
-                        }
+                    if (sim->vip.xp.step != 0) {
-
-                        /* Drawing procedure has run into overtime */
-                        else {
                         sim->vip.xp.overtime = 1;
                         vipThrow(sim, 0x8000); /* TIMEERR */
                     }
 
-                    } else sim->vip.xp.frame++;
+                    /* Initiate drawing procedure */
+                    else if (sim->vip.xp.xpen) {
+                        sim->vip.dp.buffer  ^= sim->vip.xp.toggle;
+                        sim->vip.xp.enabled  = 1;
+                        sim->vip.xp.overtime = 0;
+                        sim->vip.xp.step     = 1;
+                        sim->vip.xp.toggle   = 0;
                     }
 
+                }
+
+                /* Not a game frame */
+                else sim->vip.xp.frame++;
+
                 break;
 
             /* 0ms-3ms - Idle */
@@ -765,6 +773,7 @@ static int vipEmulateDisplay(VB *sim, uint32_t clocks) {
             /* 18ms-20ms - Idle */
 
             case 8: /* 20ms - Display interval complete */
+                sim->vip.buffer ^= 1;
                 sim->vip.dp.step = 0;
                 if (vipOnFrame(sim))
                     return 1;
@@ -976,7 +985,7 @@ static void vipDrawHBias(VB *sim, World *world) {
         /* Process all visible lines */
         param = &sim->vip.ram[world->paramBase +
             ((y1 - world->gy) << 2) + (i << 1)];
-        for (y = y1; y < y2; y++, param += 2) {
+        for (y = y1; y < y2; y++, param += 4) {
 
             /* Configure window bounds */
             wnd.y1 = y;
@@ -984,7 +993,7 @@ static void vipDrawHBias(VB *sim, World *world) {
 
             /* Draw the background into the window */
             vipDrawBackground(sim->vip.shadow[i], &wnd, world,
-                mx + busReadBuffer(param, VB_S16), my);
+                mx - busReadBuffer(param, VB_S16), my);
         }
 
     }
@@ -1056,8 +1065,8 @@ static void vipDrawAffine(VB *sim, World *world) {
 
             /* Adjust left-edge parameters */
             if ((mp < 0) ^ i) {
-                mx += dx * (wx - mp);
+                mx += dx * (wx + mp);
-                my += dy * (wx - mp);
+                my += dy * (wx + mp);
             } else {
                 mx += dx * wx;
                 my += dy * wx;
@@ -1262,6 +1271,7 @@ static void vipEmulateDrawing(VB *sim, uint32_t clocks) {
             case 4: /* Drawing complete */
                 sim->vip.xp.enabled = 0;
                 sim->vip.xp.step    = 0;
+                sim->vip.xp.toggle  = 1;
                 if (sim->vip.dp.buffer == 0)
                      sim->vip.xp.f1bsy = 0;
                 else sim->vip.xp.f0bsy = 0;
@@ -1311,8 +1321,13 @@ static void vipRead(VB *sim, uint32_t address, int type, int32_t *value) {
         *value = 0;
 
     /* I/O register */
-    else if (address < 0x60000)
+    else if (address < 0x60000) {
         *value = vipReadIO(sim, address, type);
+        switch (type) {
+            case VB_S8 : *value = (int8_t ) *value; break;
+            case VB_S16: *value = (int16_t) *value; break;
+        }
+    }
 
     /* Unmapped */
     else if (address < 0x78000)
@@ -1332,7 +1347,7 @@ static void vipReset(VB *sim) {
     Character *chr;     /* Character state */
     Object    *obj;     /* Object state */
     World     *world;   /* World state */
-    int        x, y;  /* Iterators */
+    int        x, y, z; /* Iterators */
 
     /* Normal */
     sim->vip.intenb   = 0x0000;
@@ -1422,6 +1437,13 @@ static void vipReset(VB *sim) {
     sim->vip.xp.sbcount  = 0;
     sim->vip.xp.sbout    = 0;
 
+    /* Other */
+    sim->vip.buffer = 0;
+    for (x = 0; x < 2; x++)
+    for (y = 0; y < 2; y++)
+    for (z = 0; z < 384*224; z++)
+        sim->vip.output[x][y][z] = 0;
+
     /* Display processor other */
     sim->vip.dp.brt[0] = 0;
     sim->vip.dp.buffer = 0; /* TODO: Hardware might actually do this */
@@ -1432,6 +1454,7 @@ static void vipReset(VB *sim) {
     /* Pixel processor other */
     sim->vip.xp.clocks = 0;
     sim->vip.xp.step   = 0;
+    sim->vip.xp.toggle = 0;
     sim->vip.xp.until  = 0;
 }
 

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) {
@@ -57,25 +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, Channel *chan) {
-    uint32_t bit; /* Pseudorandom bit */
 
     /* Automatic shutoff */
     if (chan->int_.auto_ && chan->int_.clocks == 0) {
@@ -95,37 +126,62 @@ static void vsuEmulateChannel(VB *sim, Channel *chan) {
         /* 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 (chan->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);
         }
 
+        /* Always process and validate next frequency value */
+        vsuNextFreqMod(sim, chan);
+    }
+
 }
 
 /* Produce output for a channel */
@@ -164,8 +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);
@@ -178,6 +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) {
@@ -186,14 +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);
-            chan->freqmod =
-                sim->vsu.freqmod.enb && sim->vsu.freqmod.interval != 0;
             break;
 
         case 5: /* Channel 6 */
             sim->vsu.noise.tap       = value >> 4 & 7;
             sim->vsu.noise.register_ = 0x0000;
+            vsuNextNoise(sim);
     }
 
 }
@@ -204,7 +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);
 }
 
@@ -213,7 +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);
 }
 
@@ -228,19 +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);
     }
 
 }
@@ -272,8 +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 =
+    sim->vsu.channels[4].freqmod = vsuCheckFreqMod(sim);
-        sim->vsu.freqmod.enb && sim->vsu.freqmod.interval != 0;
+    vsuNextFreqMod(sim, &sim->vsu.channels[4]);
 }
 
 
@@ -315,7 +394,8 @@ static void vsuEmulate(VB *sim, uint32_t clocks) {
 
                     /* Clocks until next state change */
                     chan->until = chan->clocks;
-                    if (chan->env.enb && chan->env.clocks < chan->until)
+                    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;
@@ -324,7 +404,7 @@ static void vsuEmulate(VB *sim, uint32_t clocks) {
 
                     /* Manage clocks */
                     chan->clocks -= chan->until;
-                    if (chan->env.enb)
+                    if (chan->env.enb && chan->env.modmask != 2)
                         chan->env.clocks -= chan->until;
                     if (chan->int_.auto_)
                         chan->int_.clocks -= chan->until;
@@ -427,6 +507,7 @@ static void vsuReset(VB *sim) {
         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;
@@ -447,8 +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;
@@ -465,21 +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) {

util/disassembler.c

@@ -513,6 +513,8 @@ static int dasmLine(VB *sim, uint32_t *address, uint32_t pc,
     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;
 
@@ -657,6 +659,8 @@ static VBU_DasmLine* dasmDisassemble(VB *sim, uint32_t 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;
     }
 

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

@@ -33,6 +33,7 @@ static int32_t SignExtend(int32_t value, int32_t bits) {
 /******************************** Sub-Modules ********************************/
 
 #include "disassembler.c"
+#include "isx.c"
 
 
 
@@ -70,3 +71,8 @@ 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

@@ -88,6 +88,7 @@ typedef struct {
 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);
 
 
 

web/Audio.js

@@ -1,7 +1,5 @@
 "use strict";
 
-//////////////////////////////////// Audio ////////////////////////////////////
-
 // Dedicated audio output processor
 class Audio extends AudioWorkletProcessor {
 

web/Constants.js

@@ -1,4 +1,5 @@
-let Constants = {
+"use strict";
+export default {
 
     // Core
     VB: {
@@ -85,5 +86,3 @@ let Constants = {
     }
 
 };
-
-export { Constants };

web/Core.js

@@ -1,5 +1,5 @@
 "use strict";
-import { Constants } from "./Constants.js";
+import Constants from /***/"./Constants.js";
 
 
 
@@ -87,10 +87,7 @@ new class Core {
             this.sims.set(sim.pointer, sim);
 
             // Video
-            sim.pixels = this.#noalloc(
+            sim.pixels = this.#getPixels(sim);
-                this.GetExtPixels(sim.pointer),
-                384*224*4, sim, "pixels", Uint8ClampedArray
-            );
             sim.image  = new ImageData(sim.pixels, 384, 224);
 
             // Audio
@@ -261,6 +258,47 @@ new class Core {
         });
     }
 
+    // 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);
@@ -364,9 +402,11 @@ new class Core {
             this.mallocs.set(buffer.pointer, buffer);
             this.#updateTarget(buffer);
         }
-        for (let sim of this.sims)
+        for (let sim of this.sims.values()) {
+            sim.pixels = this.#getPixels(sim);
             sim.image  = new ImageData(sim.pixels, 384, 224);
         }
+    }
 
 
 
@@ -436,6 +476,14 @@ new class Core {
         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(

web/VB.js

@@ -1,5 +1,5 @@
 "use strict";
-import { Constants } from "./Constants.js";
+import Constants from /**/"./Constants.js";
 
 // Instantiation guard
 const GUARD = Symbol();
@@ -436,8 +436,17 @@ class Sim extends HTMLElement {
             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
-    async setAnaglyph(left, right) {
+    setAnaglyph(left, right) {
 
         // Error checking
         if (!Number.isSafeInteger(left ) || left  < 0 || left  > 0xFFFFFF)
@@ -455,7 +464,7 @@ class Sim extends HTMLElement {
         this.#anaglyph[1] = right;
 
         // Send the colors to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setAnaglyph",
             promised: true,
             sim     : this.#pointer,
@@ -475,7 +484,7 @@ class Sim extends HTMLElement {
     }
 
     // Specify new game pad keys
-    async setKeys(keys) {
+    setKeys(keys) {
 
         // Error checking
         if (!Number.isSafeInteger(keys) || keys < 0 || keys > 0xFFFF)
@@ -487,7 +496,7 @@ class Sim extends HTMLElement {
         this.#keys = keys;
 
         // Send the keys to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setKeys",
             promised: true,
             sim     : this.#pointer,
@@ -496,7 +505,7 @@ class Sim extends HTMLElement {
     }
 
     // Specify audio panning
-    async setPanning(panning) {
+    setPanning(panning) {
 
         // Error checking
         if (!Number.isFinite(panning) ||panning < -1 || panning > +1) {
@@ -508,7 +517,7 @@ class Sim extends HTMLElement {
         this.#panning = panning;
 
         // Send the panning to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setPanning",
             promised: true,
             sim     : this.#pointer,
@@ -529,7 +538,7 @@ class Sim extends HTMLElement {
     }
 
     // Specify audio volume
-    async setVolume(volume) {
+    setVolume(volume) {
 
         // Error checking
         if (!Number.isFinite(volume) ||volume < 0 || volume > 10) {
@@ -541,7 +550,7 @@ class Sim extends HTMLElement {
         this.#volume = volume;
 
         // Send the volume to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setVolume",
             promised: true,
             sim     : this.#pointer,
@@ -596,7 +605,7 @@ class VB {
     #commands;  // Computed method table
     #core;      // Core worker
     #proxy;     // Self proxy for sim access
-    #sims;      // All sims
+    #sims;      // Mapping of Sim|pointer -> proxy
     #state;     // Operations state
 
 
@@ -683,8 +692,8 @@ class VB {
     ///////////////////////////// Static Methods //////////////////////////////
 
     // Create a core instance
-    static async create(options) {
+    static create(options) {
-        return await new VB(GUARD).#construct(options);
+        return new VB(GUARD).#construct(options);
     }
 
 
@@ -769,6 +778,16 @@ class VB {
 
 
 
+    /////////////////////////////// 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
@@ -809,7 +828,7 @@ class VB {
         if (
             !Array.isArray(sims) ||
             sims.length == 0     ||
-            sims.find(s=>!this.#sims.has(s))
+            sims.some(s=>!this.#sims.has(s))
         ) {
             throw new TypeError("Must specify a Sim or array of Sims " +
                 "that belong to this core.");
@@ -864,6 +883,28 @@ class VB {
         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() {
 
@@ -932,4 +973,4 @@ class VB {
 
 }
 
-export { VB };
+export default VB;