/* This file is included into vb.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_DasmLine *line) {
    sprintf(dest, "%d", SignExtend(line->code[0], 5));
}

/* Format a 5-bit zero-filled immediate operand */
static void dasmOpImm5U(char *dest, VBU_DasmLine *line) {
    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 (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];
    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];
}

/* Determine the size of an instruction */
static uint32_t dasmInstSize(VB *sim, uint32_t address) {
    unsigned opcode = vbRead(sim, address, VB_U16) >> 10 & 63;
    return opcode < 0x20 || opcode == 0x32 || opcode == 0x36 ? 2 : 4;
}

/* 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,         line); break;
        case DASM_IMM5U : dasmOpImm5U (dest,         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 = dasmInstSize(sim, *address);
    line->isPC       = *address == pc;
    for (x = 0; x < line->codeLength; x++)
        line->code[x] = vbRead(sim, *address + x, VB_U8);
    *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 = dasmInstSize(sim, addr);
        if (address - addr < size)
            break;
        addr += 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 += dasmInstSize(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 lines;

    /* Exception handler */
    catch:
    circle = VBU_REALLOC(circle, 0);
    lines  = VBU_REALLOC(lines , 0);
    return NULL;
}



#endif /* VBUAPI */