380 lines
8.4 KiB
C
380 lines
8.4 KiB
C
// http://devernay.free.fr/hacks/chip8/C8TECH10.HTM
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
#define READ_INS() \
|
|
uint8_t low = c->memory[c->pc++]; \
|
|
uint8_t high = c->memory[c->pc++]; \
|
|
uint16_t ins = (low << 8) | high; \
|
|
uint16_t nnn = ins & 0x0FFF; \
|
|
uint8_t n = ins & 0x000F; \
|
|
uint8_t x = (ins >> 8) & 0x0F; \
|
|
uint8_t y = (ins >> 4) & 0x0F; \
|
|
uint8_t kk = ins & 0x00FF
|
|
|
|
#define BAD_INS() \
|
|
fprintf(stderr, "unrecognized instruction\n"); \
|
|
exit(1)
|
|
|
|
typedef struct CHIP8 {
|
|
uint8_t *memory;
|
|
uint16_t pc;
|
|
uint16_t stack[16];
|
|
uint8_t sp;
|
|
uint8_t reg[16];
|
|
uint16_t I;
|
|
uint8_t delay_timer;
|
|
uint8_t sound_timer;
|
|
} CHIP8;
|
|
|
|
CHIP8 chip8_create() {
|
|
static const uint8_t fonts[] = {
|
|
0xF0, 0x90, 0x90, 0x90, 0xF0, // 0
|
|
0x20, 0x60, 0x20, 0x20, 0x70, // 1
|
|
0xF0, 0x10, 0xF0, 0x80, 0xF0, // 2
|
|
0xF0, 0x10, 0xF0, 0x10, 0xF0, // 3
|
|
0x90, 0x90, 0xF0, 0x10, 0x10, // 4
|
|
0xF0, 0x80, 0xF0, 0x10, 0xF0, // 5
|
|
0xF0, 0x80, 0xF0, 0x90, 0xF0, // 6
|
|
0xF0, 0x10, 0x20, 0x40, 0x40, // 7
|
|
0xF0, 0x90, 0xF0, 0x90, 0xF0, // 8
|
|
0xF0, 0x90, 0xF0, 0x10, 0xF0, // 9
|
|
0xF0, 0x90, 0xF0, 0x90, 0x90, // A
|
|
0xE0, 0x90, 0xE0, 0x90, 0xE0, // B
|
|
0xF0, 0x80, 0x80, 0x80, 0xF0, // C
|
|
0xE0, 0x90, 0x90, 0x90, 0xE0, // D
|
|
0xF0, 0x80, 0xF0, 0x80, 0xF0, // E
|
|
0xF0, 0x80, 0xF0, 0x80, 0x80, // F
|
|
};
|
|
CHIP8 c = {0};
|
|
c.memory = calloc(1, 4096);
|
|
for (size_t i = 0; i < 80; i++)
|
|
c.memory[i] = fonts[i];
|
|
c.pc = 0x200;
|
|
return c;
|
|
}
|
|
|
|
void chip8_disassemble(CHIP8 *c, size_t ins_count) {
|
|
for (size_t i = 0; i < ins_count; i++) {
|
|
READ_INS();
|
|
|
|
printf("0x%x: ", c->pc);
|
|
|
|
switch ((ins >> 12) & 0xF) {
|
|
case 0x0: {
|
|
switch (nnn) {
|
|
case 0x0E0:
|
|
puts("CLS");
|
|
break;
|
|
case 0x0EE:
|
|
puts("RET");
|
|
break;
|
|
default:
|
|
printf("SYS %u\n", nnn);
|
|
}
|
|
} break;
|
|
case 0x1: {
|
|
printf("JP 0x%x\n", nnn);
|
|
} break;
|
|
case 0x2: {
|
|
printf("CALL %u\n", nnn);
|
|
} break;
|
|
case 0x3: {
|
|
printf("SE V%x, %u\n", x, kk);
|
|
} break;
|
|
case 0x4: {
|
|
printf("SNE V%x, %u\n", x, kk);
|
|
} break;
|
|
case 0x5: {
|
|
printf("SE V%x, V%x\n", x, y);
|
|
} break;
|
|
case 0x6: {
|
|
printf("LD V%x, %u\n", x, kk);
|
|
} break;
|
|
case 0x7: {
|
|
printf("ADD V%x, %u\n", x, kk);
|
|
} break;
|
|
case 0x8: {
|
|
switch (n) {
|
|
case 0x0:
|
|
printf("LD V%x, V%x\n", x, y);
|
|
break;
|
|
case 0x1:
|
|
printf("OR V%x, V%x\n", x, y);
|
|
break;
|
|
case 0x2:
|
|
printf("AND V%x, V%x\n", x, y);
|
|
break;
|
|
case 0x3:
|
|
printf("XOR V%x, V%x\n", x, y);
|
|
break;
|
|
case 0x4:
|
|
printf("ADD V%x, V%x\n", x, y);
|
|
break;
|
|
case 0x5:
|
|
printf("SUB V%x, V%x\n", x, y);
|
|
break;
|
|
case 0x6:
|
|
printf("SHR V%x\n", x);
|
|
break;
|
|
case 0x7:
|
|
printf("SUBN V%x, V%x\n", x, y);
|
|
break;
|
|
case 0xE:
|
|
printf("SHL V%x\n", x);
|
|
break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
} break;
|
|
case 0x9: {
|
|
printf("SNE V%x, V%x\n", x, y);
|
|
} break;
|
|
case 0xA: {
|
|
printf("LD I, 0x%x\n", nnn);
|
|
} break;
|
|
case 0xB: {
|
|
printf("JP V0, %u\n", nnn);
|
|
} break;
|
|
case 0xC: {
|
|
printf("RND V%x, %u\n", x, kk);
|
|
} break;
|
|
case 0xD: {
|
|
printf("DRW V%x, V%x, %u\n", x, y, n);
|
|
} break;
|
|
case 0xE: {
|
|
switch (kk) {
|
|
case 0x9E:
|
|
printf("SKP V%x\n", x);
|
|
break;
|
|
case 0xA1:
|
|
printf("SKNP V%x\n", x);
|
|
break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
} break;
|
|
case 0xF: {
|
|
switch (kk) {
|
|
case 0x07:
|
|
printf("LD V%x, DT\n", x);
|
|
break;
|
|
case 0x0A:
|
|
printf("LD V%x, K\n", x);
|
|
break;
|
|
case 0x15:
|
|
printf("LD DT, V%x\n", x);
|
|
break;
|
|
case 0x18:
|
|
printf("LD ST, V%x\n", x);
|
|
break;
|
|
case 0x1E:
|
|
printf("ADD I, V%x\n", x);
|
|
break;
|
|
case 0x29:
|
|
printf("LD F, V%x\n", x);
|
|
break;
|
|
case 0x33:
|
|
printf("LD B, V%x\n", x);
|
|
break;
|
|
case 0x55:
|
|
printf("LD [I], V%x\n", x);
|
|
break;
|
|
case 0x65:
|
|
printf("LD V%x, [I]\n", x);
|
|
break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
} break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
}
|
|
}
|
|
|
|
void chip8_execute(CHIP8 *c) {
|
|
while (1) {
|
|
READ_INS();
|
|
|
|
switch ((ins >> 12) & 0xF) {
|
|
case 0x0: {
|
|
switch (nnn) {
|
|
case 0x0E0:
|
|
puts("TODO: CLS");
|
|
break;
|
|
case 0x0EE:
|
|
c->pc = c->stack[c->sp];
|
|
c->sp--;
|
|
break;
|
|
default:
|
|
c->pc = nnn;
|
|
}
|
|
} break;
|
|
case 0x1: {
|
|
c->pc = nnn;
|
|
} break;
|
|
case 0x2: {
|
|
c->sp++;
|
|
c->stack[c->sp] = c->pc;
|
|
c->pc = nnn;
|
|
} break;
|
|
case 0x3: {
|
|
if (c->reg[x] == kk) {
|
|
c->pc += 2;
|
|
}
|
|
} break;
|
|
case 0x4: {
|
|
if (c->reg[x] != kk) {
|
|
c->pc += 2;
|
|
}
|
|
} break;
|
|
case 0x5: {
|
|
if (c->reg[x] == c->reg[y]) {
|
|
c->pc += 2;
|
|
}
|
|
} break;
|
|
case 0x6: {
|
|
c->reg[x] = kk;
|
|
} break;
|
|
case 0x7: {
|
|
c->reg[x] += kk;
|
|
} break;
|
|
case 0x8: {
|
|
switch (n) {
|
|
case 0x0:
|
|
c->reg[x] = c->reg[y];
|
|
break;
|
|
case 0x1:
|
|
c->reg[x] |= c->reg[y];
|
|
break;
|
|
case 0x2:
|
|
c->reg[x] &= c->reg[y];
|
|
break;
|
|
case 0x3:
|
|
c->reg[x] ^= c->reg[y];
|
|
break;
|
|
case 0x4: {
|
|
uint16_t res = (uint16_t)(c->reg[x]) + (uint16_t)c->reg[y];
|
|
c->reg[0xF] = res > 0xFF;
|
|
c->reg[x] = (uint8_t)(res & 0xFF);
|
|
} break;
|
|
case 0x5:
|
|
c->reg[0xF] = c->reg[x] > c->reg[y];
|
|
c->reg[x] -= c->reg[y];
|
|
break;
|
|
case 0x6:
|
|
c->reg[0xF] = c->reg[x] & 0x1;
|
|
c->reg[x] >>= 1;
|
|
break;
|
|
case 0x7:
|
|
c->reg[0xF] = c->reg[y] > c->reg[x];
|
|
c->reg[x] = c->reg[y] - c->reg[x];
|
|
break;
|
|
case 0xE:
|
|
c->reg[0xF] = (c->reg[x] & 0b10000000) >> 7;
|
|
c->reg[x] <<= 1;
|
|
break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
} break;
|
|
case 0x9: {
|
|
if (c->reg[x] != c->reg[y]) {
|
|
c->pc += 2;
|
|
}
|
|
} break;
|
|
case 0xA: {
|
|
c->I = nnn;
|
|
} break;
|
|
case 0xB: {
|
|
c->pc = nnn + c->reg[0];
|
|
} break;
|
|
case 0xC: {
|
|
c->reg[x] = (rand() % 256) & kk;
|
|
} break;
|
|
case 0xD: {
|
|
printf("TODO: DRW V%x, V%x, %u\n", x, y, n);
|
|
} break;
|
|
case 0xE: {
|
|
switch (kk) {
|
|
case 0x9E:
|
|
printf("TODO: SKP V%x\n", x);
|
|
break;
|
|
case 0xA1:
|
|
printf("TODO: SKNP V%x\n", x);
|
|
break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
} break;
|
|
case 0xF: {
|
|
switch (kk) {
|
|
case 0x07:
|
|
c->reg[x] = c->delay_timer;
|
|
break;
|
|
case 0x0A:
|
|
printf("TODO: LD V%x, K\n", x);
|
|
break;
|
|
case 0x15:
|
|
c->delay_timer = c->reg[x];
|
|
break;
|
|
case 0x18:
|
|
c->sound_timer = c->reg[x];
|
|
break;
|
|
case 0x1E:
|
|
c->I += c->reg[x];
|
|
break;
|
|
case 0x29:
|
|
c->I = c->reg[x] * 5;
|
|
break;
|
|
case 0x33:
|
|
c->memory[c->I] = c->reg[x] / 100;
|
|
c->memory[c->I + 1] = (c->reg[x] / 10) % 10;
|
|
c->memory[c->I + 2] = c->reg[x] % 10;
|
|
break;
|
|
case 0x55:
|
|
for (size_t i = 0; i <= x; i++) {
|
|
c->memory[c->I + i] = c->reg[i];
|
|
}
|
|
break;
|
|
case 0x65:
|
|
for (size_t i = 0; i <= x; i++) {
|
|
c->reg[i] = c->memory[c->I + i];
|
|
}
|
|
break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
} break;
|
|
default:
|
|
BAD_INS();
|
|
}
|
|
}
|
|
}
|
|
|
|
void chip8_free(CHIP8 c) { free(c.memory); }
|
|
|
|
int main(int argc, char *argv[]) {
|
|
if (argc < 2) {
|
|
fprintf(stderr, "Usage: %s <path>\n", argv[0]);
|
|
return 1;
|
|
}
|
|
|
|
CHIP8 c = chip8_create();
|
|
|
|
uint8_t buffer[4000];
|
|
FILE *f = fopen(argv[1], "rb");
|
|
size_t n = fread(buffer, 1, 4000, f);
|
|
fclose(f);
|
|
|
|
for (size_t i = 0; i < n; i++) {
|
|
c.memory[0x200 + i] = buffer[i];
|
|
}
|
|
|
|
// chip8_disassemble(&c, n / 2);
|
|
chip8_execute(&c);
|
|
|
|
chip8_free(c);
|
|
} |