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This commit is contained in:
Antoni Piasecki
2025-07-18 17:09:47 +02:00
parent 06b0192bb9
commit a334740040
1 changed files with 22 additions and 3 deletions
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25
mos6502.c
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@@ -1,4 +1,5 @@
// https://www.masswerk.at/6502/6502_instruction_set.html // https://www.masswerk.at/6502/6502_instruction_set.html
// TODO: IO
// TODO: decimal mode // TODO: decimal mode
// TODO: interrupts? // TODO: interrupts?
// TODO: cycles? // TODO: cycles?
@@ -25,6 +26,8 @@ typedef struct MOS6502 {
uint8_t Y; uint8_t Y;
uint8_t SP; uint8_t SP;
uint8_t P; uint8_t P;
uint8_t display_modified_this_cycle;
} MOS6502; } MOS6502;
void mos6502_disassemble(MOS6502 *m); void mos6502_disassemble(MOS6502 *m);
@@ -55,13 +58,14 @@ uint8_t mos6502_mem_read(MOS6502 *m, uint16_t addr) { return m->memory[addr]; }
void mos6502_mem_write(MOS6502 *m, uint16_t addr, uint8_t v) { void mos6502_mem_write(MOS6502 *m, uint16_t addr, uint8_t v) {
m->memory[addr] = v; m->memory[addr] = v;
if (addr == 0x0400) { if (0x0400 <= addr && addr < 0x0600) {
printf("%c", m->memory[addr]); m->display_modified_this_cycle = 1;
fflush(stdout);
} }
} }
void mos6502_step(MOS6502 *m) { void mos6502_step(MOS6502 *m) {
m->display_modified_this_cycle = 0;
uint8_t op = READ_U8(); uint8_t op = READ_U8();
switch (op) { switch (op) {
case 0x00: { case 0x00: {
@@ -1413,7 +1417,22 @@ int main(int argc, char *argv[]) {
m.pc = old_pc; m.pc = old_pc;
printf("\tA: %02X X: %02X Y: %02X\n", m.A, m.X, m.Y); printf("\tA: %02X X: %02X Y: %02X\n", m.A, m.X, m.Y);
} }
mos6502_step(&m); mos6502_step(&m);
if (m.display_modified_this_cycle) {
static char buf[1024];
size_t p = 0;
for (size_t y = 0; y < 16; y++) {
for (size_t x = 0; x < 32; x++) {
char c = mos6502_mem_read(&m, 0x0400 + x + (y * 32));
buf[p++] = c == 0 ? ' ' : c;
}
buf[p++] = '\n';
}
buf[p] = '\0';
printf("\x1b[?25l%s\x1b[8A\x1b[8A", buf);
}
} }
} }