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0e5dfdb808f6c8f2c86087d52da2a50569e252da
chip/main.c
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531 lines
14 KiB
C
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#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdint.h>
#include <signal.h>
#include <string.h>
#include <math.h>
#include <raylib.h>
#define MEMORY_SIZE 4096
#define PROGRAM_START 512
#define FONT_START 80
#define CPU_CLOCK_HZ 600
#define TIMER_HZ 60
#define SCREEN_WIDTH 64
#define SCREEN_HEIGHT 32
enum OpcodeGroups {
OPCODE_GROUP_SYS_OR_RET = 0,
OPCODE_GROUP_JUMP = 4096,
OPCODE_GROUP_CALL = 8192,
OPCODE_GROUP_SE_VX_BYTE = 12288,
OPCODE_GROUP_SNE_VX_BYTE = 16384,
OPCODE_GROUP_SE_VX_VY = 20480,
OPCODE_GROUP_LD_VX_BYTE = 24576,
OPCODE_GROUP_ADD_VX_BYTE = 28672,
OPCODE_GROUP_ARITHMETIC = 32768,
OPCODE_GROUP_SNE_VX_VY = 36864,
OPCODE_GROUP_LD_I_ADDR = 40960,
OPCODE_GROUP_JP_V0_ADDR = 45056,
OPCODE_GROUP_RND_VX_BYTE = 49152,
OPCODE_GROUP_DRW_VX_VY_N = 53248,
OPCODE_GROUP_KEY_SKIP = 57344,
OPCODE_GROUP_MISC = 61440
};
enum SysOpcodes {
OPCODE_CLS = 224,
OPCODE_RET = 238
};
enum ArithmeticSubOpcodes {
SUB_OP_LD = 0,
SUB_OP_OR = 1,
SUB_OP_AND = 2,
SUB_OP_XOR = 3,
SUB_OP_ADD = 4,
SUB_OP_SUB = 5,
SUB_OP_SHR = 6,
SUB_OP_SUBN = 7,
SUB_OP_SHL = 14
};
enum KeySkipOpcodes {
OPCODE_SKP = 158,
OPCODE_SKNP = 161
};
enum MiscSubOpcodes {
SUB_OP_LD_VX_DT = 7,
SUB_OP_LD_VX_K = 10,
SUB_OP_LD_DT_VX = 21,
SUB_OP_LD_ST_VX = 24,
SUB_OP_ADD_I_VX = 30,
SUB_OP_LD_F_VX = 41,
SUB_OP_LD_B_VX = 51,
SUB_OP_LD_I_REG = 85,
SUB_OP_LD_REG_I = 101
};
const uint8_t fontset[80] = {
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
};
const int CYCLES_PER_FRAME = CPU_CLOCK_HZ / TIMER_HZ;
volatile sig_atomic_t keep_running = 1;
void handle_sigint(int sig) {
(void)sig;
keep_running = 0;
}
enum ExitCodes {
COMPLETED_SUCCESSFULLY,
FILE_NOT_PROVIDED,
FILE_MISSING,
PROGRAM_TOO_LARGE,
MEMORY_ALLOCATION_FAILURE,
};
// TODO: Add additional members
// i.e. registers
typedef struct ChipEight {
uint8_t memory[MEMORY_SIZE];
uint16_t pc;
uint16_t I;
uint8_t V[16];
uint8_t dt;
uint8_t st;
uint16_t stack[16];
uint8_t sc;
uint32_t display[SCREEN_WIDTH * SCREEN_HEIGHT];
uint8_t keys[16];
uint8_t key_register;
bool waiting_for_key;
} chip_eight_t;
void println(const char *format, ...) {
va_list args;
va_start(args, format);
vprintf(format, args);
va_end(args);
printf("\n");
}
void setup_graceful_exit() {
signal(SIGINT, handle_sigint);
signal(SIGTERM, handle_sigint);
}
int load_rom(chip_eight_t *chip, char *file_path) {
FILE *file_ptr = fopen(file_path, "rb");
if (file_ptr == NULL) {
return FILE_MISSING;
}
fseek(file_ptr, 0, SEEK_END);
int num_of_bytes = ftell(file_ptr);
int max_program_size = MEMORY_SIZE - PROGRAM_START;
if (num_of_bytes > max_program_size) {
fclose(file_ptr);
return PROGRAM_TOO_LARGE;
}
fseek(file_ptr, 0, SEEK_SET);
fread(&chip->memory[PROGRAM_START], sizeof(uint8_t), num_of_bytes, file_ptr);
fclose(file_ptr);
return COMPLETED_SUCCESSFULLY;
}
void init_chip(chip_eight_t *chip) {
memset(chip, 0, sizeof(chip_eight_t));
chip->pc = PROGRAM_START;
chip->dt = 0;
chip->st = 0;
chip->waiting_for_key = false;
for (int i = 0; i < 80; i++) {
chip->memory[FONT_START + i] = fontset[i];
}
}
void draw_sprite(chip_eight_t *chip, uint16_t n, uint16_t x, uint16_t y) {
uint8_t x_coordinate = chip->V[x] % SCREEN_WIDTH;
uint8_t y_coordinate = chip->V[y] % SCREEN_HEIGHT;
chip->V[15] = 0;
for (int row = 0; row < n; row++) {
uint8_t sprite_byte = chip->memory[chip->I + row];
if ((y_coordinate + row) >= SCREEN_HEIGHT) {
break;
}
for (int col = 0; col < 8; col++) {
if ((x_coordinate + col) >= SCREEN_WIDTH) {
break;
}
// extracting individual bits (pixels) from byte in memory
uint8_t sprite_pixel = sprite_byte & (128 >> col);
// flatten 2-d coordinates to index
int sprite_screen_index = ((y_coordinate + row) * SCREEN_WIDTH) + (x_coordinate + col);
uint32_t *screen_pixel = &chip->display[sprite_screen_index];
if (sprite_pixel != 0) {
if (*screen_pixel == 1) {
chip->V[15] = 1;
}
*screen_pixel ^= 1;
}
}
}
}
void update_keys(chip_eight_t *chip) {
chip->keys[1] = IsKeyDown(KEY_ONE);
chip->keys[2] = IsKeyDown(KEY_TWO);
chip->keys[3] = IsKeyDown(KEY_THREE);
chip->keys[12] = IsKeyDown(KEY_FOUR);
chip->keys[4] = IsKeyDown(KEY_Q);
chip->keys[5] = IsKeyDown(KEY_W);
chip->keys[6] = IsKeyDown(KEY_E);
chip->keys[13] = IsKeyDown(KEY_R);
chip->keys[7] = IsKeyDown(KEY_A);
chip->keys[8] = IsKeyDown(KEY_S);
chip->keys[9] = IsKeyDown(KEY_D);
chip->keys[14] = IsKeyDown(KEY_F);
chip->keys[10] = IsKeyDown(KEY_Z);
chip->keys[0] = IsKeyDown(KEY_X);
chip->keys[11] = IsKeyDown(KEY_C);
chip->keys[15] = IsKeyDown(KEY_V);
}
int main(int argc, char *argv[]) {
setup_graceful_exit();
if (argc < 2) {
println("You fucked up bro! We need a file to load into memory.");
println("Usage: chip.exe <file-to-load>");
return FILE_NOT_PROVIDED;
}
chip_eight_t *chip = malloc(sizeof(chip_eight_t));
if (chip == NULL) {
println("Failed to allocate memory for chip.");
return MEMORY_ALLOCATION_FAILURE;
}
init_chip(chip);
int load_rom_result = load_rom(chip, argv[1]);
if (load_rom_result != COMPLETED_SUCCESSFULLY) {
if (load_rom_result == FILE_MISSING) {
println("Error: The file '%s' could not be found or opened.", argv[1]);
} else if (load_rom_result == PROGRAM_TOO_LARGE) {
println("Error: The program is too large to fit in CHIP-8 memory.");
} else {
println("Error: Failed to load ROM (code %d).", load_rom_result);
}
free(chip);
return load_rom_result;
}
// Setup audio
InitAudioDevice();
// Generate 440Hz Sine wave beep in memory
int sampleRate = 44100;
float durationSeconds = 0.1f;
int frameCount = sampleRate * durationSeconds;
float *data = (float *)malloc(frameCount * sizeof(float));
if (data != NULL) {
for (int i = 0; i < frameCount; i++) {
data[i] = sinf(2.0f * PI * 440.0f * ((float)i / sampleRate)) * 0.2f;
}
}
Wave wave = { 0 };
wave.frameCount = frameCount;
wave.sampleRate = sampleRate;
wave.sampleSize = 32;
wave.channels = 1;
wave.data = data;
Sound beep_sound = LoadSoundFromWave(wave);
UnloadWave(wave); // Frees the 'data' buffer in system RAM
int scale_factor = 10;
int display_width = SCREEN_WIDTH * scale_factor;
int display_height = SCREEN_HEIGHT * scale_factor;
InitWindow(display_width, display_height, "chip");
SetTargetFPS(60);
while(!WindowShouldClose() && keep_running)
{
update_keys(chip);
if (chip->waiting_for_key) {
bool key_pressed = false;
for (int i = 0; i < 16; i++) {
if (chip->keys[i]) {
chip->V[chip->key_register] = i;
chip->waiting_for_key = false;
key_pressed = true;
break;
}
}
if (!key_pressed) {
BeginDrawing();
ClearBackground(BLACK);
for (int i = 0; i < SCREEN_HEIGHT; i++) {
for (int j = 0; j < SCREEN_WIDTH; j++) {
uint32_t screen_pixel = chip->display[i * SCREEN_WIDTH + j];
if (screen_pixel == 1) {
DrawRectangle(j * scale_factor, i * scale_factor, scale_factor, scale_factor, RAYWHITE);
}
}
}
EndDrawing();
continue;
}
}
for(int i = 0; i < CYCLES_PER_FRAME; i++) {
if (chip->waiting_for_key) {
break;
}
// read 2 bytes at a time from memory
// reading first 1 byte shifting left 1 byte ORing 2 byte
uint16_t opcode = (chip->memory[chip->pc] << 8) | (chip->memory[chip->pc + 1]);
chip->pc += 2;
// extracting the lowest 12 bits of the instruction
uint16_t nnn = opcode & 4095;
//extracting the lowest 8 bits of the instruction
uint8_t nn = opcode & 255;
//extracting the lowest 4 bits of the instruction
uint16_t n = opcode & 15;
// extracting the lower 4 bits of the high byte of the instruction
uint16_t x = (opcode & 3840) >> 8;
// extracting the upper 4 bits of the low byte of the instruction
uint16_t y = (opcode & 240) >> 4;
// extracting the lowest 8 bits of the instruction
uint16_t kk = opcode & 255;
switch(opcode & 61440) {
case OPCODE_GROUP_SYS_OR_RET:
if (opcode == OPCODE_CLS) {
memset(chip->display, 0, sizeof(chip->display));
} else if (opcode == OPCODE_RET) {
chip->sc -= 1;
chip->pc = chip->stack[chip->sc];
}
break;
case OPCODE_GROUP_JUMP:
chip->pc = nnn;
break;
case OPCODE_GROUP_CALL:
chip->stack[chip->sc] = chip->pc;
chip->sc += 1;
chip->pc = nnn;
break;
case OPCODE_GROUP_SE_VX_BYTE:
if (chip->V[x] == kk) {
chip->pc += 2;
}
break;
case OPCODE_GROUP_SNE_VX_BYTE:
if (chip->V[x] != kk) {
chip->pc += 2;
}
break;
case OPCODE_GROUP_SE_VX_VY:
if (chip->V[x] == chip->V[y]) {
chip->pc += 2;
}
break;
case OPCODE_GROUP_LD_VX_BYTE:
chip->V[x] = kk;
break;
case OPCODE_GROUP_ADD_VX_BYTE:
chip->V[x] += kk;
break;
case OPCODE_GROUP_ARITHMETIC:
if (n == SUB_OP_LD) {
chip->V[x] = chip->V[y];
} else if (n == SUB_OP_OR) {
chip->V[x] = chip->V[x] | chip->V[y];
} else if (n == SUB_OP_AND) {
chip->V[x] = chip->V[x] & chip->V[y];
} else if (n == SUB_OP_XOR) {
chip->V[x] = chip->V[x] ^ chip->V[y];
} else if (n == SUB_OP_ADD) {
uint16_t r = chip->V[x] + chip->V[y];
chip->V[15] = (r > 255) ? 1 : 0;
chip->V[x] = r & 255;
} else if (n == SUB_OP_SUB) {
chip->V[15] = (chip->V[x] >= chip->V[y]) ? 1 : 0;
chip->V[x] = chip->V[x] - chip->V[y];
} else if (n == SUB_OP_SHR) {
uint8_t flag = chip->V[x] & 1;
chip->V[15] = flag;
chip->V[x] /= 2;
} else if (n == SUB_OP_SUBN) {
chip->V[15] = (chip->V[y] >= chip->V[x]) ? 1 : 0;
chip->V[x] = chip->V[y] - chip->V[x];
} else if (n == SUB_OP_SHL) {
uint8_t flag = (chip->V[x] & 128) >> 7;
chip->V[15] = flag;
chip->V[x] *= 2;
}
break;
case OPCODE_GROUP_SNE_VX_VY:
if (chip->V[x] != chip->V[y]) {
chip->pc += 2;
}
break;
case OPCODE_GROUP_LD_I_ADDR:
chip->I = nnn;
break;
case OPCODE_GROUP_JP_V0_ADDR:
chip->pc = nnn + chip->V[0];
break;
case OPCODE_GROUP_RND_VX_BYTE:
uint8_t num = rand() % 256;
chip->V[x] = kk & num;
break;
case OPCODE_GROUP_DRW_VX_VY_N:
draw_sprite(chip, n, x, y);
break;
case OPCODE_GROUP_KEY_SKIP:
if (nn == OPCODE_SKP) {
if (chip->keys[chip->V[x] & 0x0F] == 1) {
chip->pc += 2;
}
} else if (nn == OPCODE_SKNP) {
if (chip->keys[chip->V[x] & 0x0F] != 1) {
chip->pc += 2;
}
}
break;
case OPCODE_GROUP_MISC:
if (nn == SUB_OP_LD_VX_DT) {
chip->V[x] = chip->dt;
} else if (nn == SUB_OP_LD_VX_K) {
chip->waiting_for_key = true;
chip->key_register = x;
} else if (nn == SUB_OP_LD_DT_VX) {
chip->dt = chip->V[x];
} else if (nn == SUB_OP_LD_ST_VX) {
chip->st = chip->V[x];
} else if (nn == SUB_OP_ADD_I_VX) {
chip->I += chip->V[x];
} else if (nn == SUB_OP_LD_F_VX) {
chip->I = FONT_START + ((chip->V[x] & 0x0F) * 5);
} else if (nn == SUB_OP_LD_B_VX) {
chip->memory[chip->I] = chip->V[x] / 100;
chip->memory[chip->I + 1] = (chip->V[x] / 10) % 10;
chip->memory[chip->I + 2] = chip->V[x] % 10;
} else if (nn == SUB_OP_LD_I_REG) {
for (int i = 0; i <= x; i++) {
chip->memory[chip->I + i] = chip->V[i];
}
} else if (nn == SUB_OP_LD_REG_I) {
for (int i = 0; i <= x; i++) {
chip->V[i] = chip->memory[chip->I + i];
}
}
break;
default:
break;
}
}
if (chip->dt > 0) {
chip->dt--;
}
if (chip->st > 0) {
chip->st--;
if (!IsSoundPlaying(beep_sound)) {
PlaySound(beep_sound);
}
} else {
if (IsSoundPlaying(beep_sound)) {
StopSound(beep_sound);
}
}
BeginDrawing();
ClearBackground(BLACK);
for (int i = 0; i < SCREEN_HEIGHT; i++) {
for (int j = 0; j < SCREEN_WIDTH; j++) {
uint32_t screen_pixel = chip->display[i * SCREEN_WIDTH + j];
if (screen_pixel == 1) {
DrawRectangle(j * scale_factor, i * scale_factor, scale_factor, scale_factor, RAYWHITE);
}
}
}
EndDrawing();
}
free(chip);
UnloadSound(beep_sound);
CloseAudioDevice();
CloseWindow();
return COMPLETED_SUCCESSFULLY;
}
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