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disassemble more instructions

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This commit is contained in:
Antoni Piasecki
2025-07-12 17:21:44 +02:00
parent 3722260228
commit 904ec6541f
1 changed files with 88 additions and 12 deletions
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100
mos6502.c
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@@ -12,47 +12,119 @@
typedef struct MOS6502 {
uint8_t *memory;
uint16_t pc;
uint8_t A;
uint8_t X;
uint8_t Y;
uint8_t SP;
uint8_t P;
// TODO
// uint8_t A;
// uint8_t X;
// uint8_t Y;
// uint8_t SP;
// uint8_t P;
} MOS6502;
MOS6502 mos6502_create() {
MOS6502 m = {0};
m.pc = 0x600;
m.memory = malloc(1 << 16);
m.memory = calloc(1, 1 << 16);
return m;
}
void mos6502_disassemble(MOS6502 *m, size_t ins_count) {
for (size_t i = 0; i < ins_count; i++) {
printf("%04X: ", m->pc);
uint8_t op = m->memory[m->pc++];
switch (op) {
case 0x00: {
printf("BRK\n");
} break;
case 0x18: {
printf("CLC\n");
} break;
case 0x20: {
READ_ADDR();
printf("JSR $%04X\n", addr);
} break;
case 0x38: {
printf("SEC\n");
} break;
case 0x4C: {
READ_ADDR();
printf("JMP $%X\n", addr);
printf("JMP $%04X\n", addr);
} break;
case 0x60: {
printf("RTS\n");
} break;
case 0x69: {
printf("ADC #$%02X\n", m->memory[m->pc++]);
} break;
case 0x85: {
printf("STA #$%02X\n", m->memory[m->pc++]);
} break;
case 0x8C: {
READ_ADDR();
printf("STY $%04X\n", addr);
} break;
case 0x8D: {
READ_ADDR();
printf("STA $%X\n", addr);
printf("STA $%04X\n", addr);
} break;
case 0x8E: {
READ_ADDR();
printf("STX $%04X\n", addr);
} break;
case 0x90: {
int8_t offset = m->memory[m->pc++];
printf("BCC $%04X\n", m->pc + offset);
} break;
case 0x99: {
READ_ADDR();
printf("STA $%04X,Y\n", addr);
} break;
case 0xA0: {
printf("LDY #$%02X\n", m->memory[m->pc++]);
} break;
case 0xA2: {
printf("LDX #$%X\n", m->memory[m->pc++]);
printf("LDX #$%02X\n", m->memory[m->pc++]);
} break;
case 0xA9: {
printf("LDA #$%02X\n", m->memory[m->pc++]);
} break;
case 0xAD: {
READ_ADDR();
printf("LDA $%04X\n", addr);
} break;
case 0xB0: {
int8_t offset = m->memory[m->pc++];
printf("BCS $%04X\n", m->pc + offset);
} break;
case 0xB1: {
printf("LDA (#$%02X),Y\n", m->memory[m->pc++]);
} break;
case 0xBD: {
READ_ADDR();
printf("LDA $%X,X\n", addr);
printf("LDA $%04X,X\n", addr);
} break;
case 0xC8: {
printf("INY\n");
} break;
case 0xC9: {
printf("CMP #$%02X\n", m->memory[m->pc++]);
} break;
case 0xD0: {
int8_t offset = m->memory[m->pc++];
printf("BNE $%04X\n", m->pc + offset);
} break;
case 0xE0: {
printf("CPX #$%02X\n", m->memory[m->pc++]);
} break;
case 0xE8: {
printf("INX\n");
} break;
case 0xE9: {
printf("SBC #$%02X\n", m->memory[m->pc++]);
} break;
case 0xF0: {
printf("BEQ %d\n", m->memory[m->pc++]);
int8_t offset = m->memory[m->pc++];
printf("BEQ $%04X\n", m->pc + offset);
} break;
default:
fprintf(stderr, "unrecognized opcode: %x\n", op);
@@ -61,6 +133,8 @@ void mos6502_disassemble(MOS6502 *m, size_t ins_count) {
}
}
void mos6502_free(MOS6502 m) { free(m.memory); }
int main(int argc, char *argv[]) {
if (argc < 2) {
fprintf(stderr, "Usage: %s <path>\n", argv[0]);
@@ -78,5 +152,7 @@ int main(int argc, char *argv[]) {
m.memory[0x600 + i] = buffer[i];
}
mos6502_disassemble(&m, 7);
mos6502_disassemble(&m, 103);
mos6502_free(m);
}