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chip8.c
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chip8.c
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#include <stdio.h>
#include <stdbool.h>
extern const int SCALE;
typedef struct {
uint8_t display[64*32]; // display de 64x32 pixels
uint8_t memory[4096]; // chip-8 possui 4 KB (4096 bytes) de memória total.
uint8_t regs[16];
uint16_t reg_I;
uint8_t DT; // delay timer
uint8_t ST; // sound timer
bool keypad[16]; // o keypad hexadecimal do Chip8.
bool waiting_for_keypress;
uint8_t waiting_for_keypress_reg;
uint16_t pc; // program counter
uint8_t sp; // stack pointer
uint16_t stack[16]; // stack (16 valores de 16 bits)
bool debug_autorun; // executar o main loop automaticamente?
} Chip;
void Chip8_Load(Chip *c, char *path) {
printf("Carregando ROM:\t%s\n", path);
long rom_length;
uint8_t *rom_buffer;
FILE *rom = fopen(path, "rb");
if (!rom) {
fprintf(stderr, "Impossível abrir a ROM para leitura!\n");
exit(1);
}
fseek(rom, 0, SEEK_END);
rom_length = ftell(rom);
rewind(rom);
rom_buffer = (uint8_t*) malloc(sizeof(uint8_t) * rom_length);
fread(rom_buffer, sizeof(uint8_t), rom_length, rom);
// escrever o conteúdo da ROM na RAM a partir de 0x200
for (int i = 0; i < rom_length; i++) {
c->memory[0x200 + i] = rom_buffer[i];
}
fclose(rom);
free(rom_buffer);
printf("%ld bytes lidos\n", rom_length);
c->debug_autorun = 1;
c->pc = 0x200;
// sprite fonts
c->memory[0x00 + 0] = 0xF0; // 0
c->memory[0x00 + 1] = 0x90;
c->memory[0x00 + 2] = 0x90;
c->memory[0x00 + 3] = 0x90;
c->memory[0x00 + 4] = 0xF0;
c->memory[0x10 + 0] = 0x20; // 1
c->memory[0x10 + 1] = 0x60;
c->memory[0x10 + 2] = 0x20;
c->memory[0x10 + 3] = 0x20;
c->memory[0x10 + 4] = 0x70;
c->memory[0x20 + 0] = 0xF0; // 2
c->memory[0x20 + 1] = 0x10;
c->memory[0x20 + 2] = 0xF0;
c->memory[0x20 + 3] = 0x80;
c->memory[0x20 + 4] = 0xF0;
c->memory[0x30 + 0] = 0xF0; // 3
c->memory[0x30 + 1] = 0x10;
c->memory[0x30 + 2] = 0xF0;
c->memory[0x30 + 3] = 0x10;
c->memory[0x30 + 4] = 0xF0;
c->memory[0x40 + 0] = 0x90; // 4
c->memory[0x40 + 1] = 0x90;
c->memory[0x40 + 2] = 0xF0;
c->memory[0x40 + 3] = 0x10;
c->memory[0x40 + 4] = 0x10;
c->memory[0x50 + 0] = 0xF0; // 5
c->memory[0x50 + 1] = 0x80;
c->memory[0x50 + 2] = 0xF0;
c->memory[0x50 + 3] = 0x10;
c->memory[0x50 + 4] = 0xF0;
c->memory[0x60 + 0] = 0xF0; // 6
c->memory[0x60 + 1] = 0x80;
c->memory[0x60 + 2] = 0xF0;
c->memory[0x60 + 3] = 0x90;
c->memory[0x60 + 4] = 0xF0;
c->memory[0x70 + 0] = 0xF0; // 7
c->memory[0x70 + 1] = 0x10;
c->memory[0x70 + 2] = 0x20;
c->memory[0x70 + 3] = 0x40;
c->memory[0x70 + 4] = 0x40;
c->memory[0x80 + 0] = 0xF0; // 8
c->memory[0x80 + 1] = 0x90;
c->memory[0x80 + 2] = 0xF0;
c->memory[0x80 + 3] = 0x90;
c->memory[0x80 + 4] = 0xF0;
c->memory[0x90 + 0] = 0xF0; // 9
c->memory[0x90 + 1] = 0x90;
c->memory[0x90 + 2] = 0xF0;
c->memory[0x90 + 3] = 0x10;
c->memory[0x90 + 4] = 0xF0;
c->memory[0xA0 + 0] = 0xF0; // A
c->memory[0xA0 + 1] = 0x90;
c->memory[0xA0 + 2] = 0xF0;
c->memory[0xA0 + 3] = 0x90;
c->memory[0xA0 + 4] = 0x90;
c->memory[0xB0 + 0] = 0xE0; // B
c->memory[0xB0 + 1] = 0x90;
c->memory[0xB0 + 2] = 0xE0;
c->memory[0xB0 + 3] = 0x90;
c->memory[0xB0 + 4] = 0xE0;
c->memory[0xC0 + 0] = 0xF0; // C
c->memory[0xC0 + 1] = 0x80;
c->memory[0xC0 + 2] = 0x80;
c->memory[0xC0 + 3] = 0x80;
c->memory[0xC0 + 4] = 0xF0;
c->memory[0xD0 + 0] = 0xE0; // D
c->memory[0xD0 + 1] = 0x90;
c->memory[0xD0 + 2] = 0x90;
c->memory[0xD0 + 3] = 0x90;
c->memory[0xD0 + 4] = 0xE0;
c->memory[0xE0 + 0] = 0xF0; // E
c->memory[0xE0 + 1] = 0x80;
c->memory[0xE0 + 2] = 0xF0;
c->memory[0xE0 + 3] = 0x80;
c->memory[0xE0 + 4] = 0xF0;
c->memory[0xF0 + 0] = 0xF0; // F
c->memory[0xF0 + 1] = 0x80;
c->memory[0xF0 + 2] = 0xF0;
c->memory[0xF0 + 3] = 0x80;
c->memory[0xF0 + 4] = 0x80;
}
void Chip8_Update(Chip *c) {
if (c->waiting_for_keypress) {
return;
}
uint16_t op = (c->memory[c->pc] << 8) | c->memory[c->pc + 1];
//printf("PC %#.3x : %#.4x \n", c->pc, op);
uint16_t arg_nnn = op & 0x0FFF;
uint8_t arg_kk = op & 0x00FF;
uint8_t arg_x = (op & 0x0F00) >> 8;
uint8_t arg_y = (op & 0x00F0) >> 4;
uint8_t arg_n = (op & 0x000F);
if (op == 0x00E0) {
// CLS limpar display
for (int i = 0; i < 32*64; i++) {
c->display[i] = 0x00;
}
} else if (op == 0x00EE) {
// RET retornar de uma subrotina
c->sp--;
c->pc = c->stack[c->sp];
} else if ((op & 0xF000) == 0x1000) {
// JP pular para nnn
c->pc = arg_nnn - 0x02;
} else if ((op & 0xF000) == 0x2000) {
// CALL
c->stack[c->sp] = c->pc;
c->sp++;
c->pc = arg_nnn - 0x02;
} else if ((op & 0xF000) == 0x3000) {
// SE Vx == kk
if (c->regs[arg_x] == arg_kk)
c->pc += 0x02;
} else if ((op & 0xF000) == 0x4000) {
// SNE Vx != kk
if (c->regs[arg_x] != arg_kk)
c->pc += 0x02;
} else if ((op & 0xF000) == 0x5000) {
// SE Vx == Vy
if (c->regs[arg_x] == c->regs[arg_y])
c->pc += 0x02;
} else if ((op & 0xF000) == 0x6000) {
// LD Vx, kk
c->regs[arg_x] = arg_kk;
} else if ((op & 0xF000) == 0x7000) {
// ADD Vx, kk
c->regs[arg_x] += arg_kk;
} else if ((op & 0xF00F) == 0x8000) {
// LD Vx, Vy
c->regs[arg_x] = c->regs[arg_y];
} else if ((op & 0xF00F) == 0x8001) {
// OR Vx, Vy
c->regs[arg_x] = c->regs[arg_x] | c->regs[arg_y];
} else if ((op & 0xF00F) == 0x8002) {
// AND Vx, Vy
c->regs[arg_x] = c->regs[arg_x] & c->regs[arg_y];
} else if ((op & 0xF00F) == 0x8003) {
// XOR Vx, Vy
c->regs[arg_x] = c->regs[arg_x] ^ c->regs[arg_y];
} else if ((op & 0xF00F) == 0x8004) {
// ADD Vx, Vy
int sum = c->regs[arg_x] + c->regs[arg_y];
c->regs[0xF] = (sum > 255) ? 1 : 0;
c->regs[arg_x] = sum & 0xFF;
} else if ((op & 0xF00F) == 0x8005) {
// SUB Vx, Vy
c->regs[0xF] = (c->regs[arg_x] > c->regs[arg_y]) ? 1 : 0;
c->regs[arg_x] = (c->regs[arg_x] - c->regs[arg_y]) & 0xFF;
} else if ((op & 0xF00F) == 0x8006) {
// SHR Vx
c->regs[0xF] = (c->regs[arg_x] & 1 == 1) ? 1 : 0;
c->regs[arg_x] = c->regs[arg_x] >> 1;
} else if ((op & 0xF00F) == 0x8007) {
// SUBN Vx, Vy
c->regs[0xF] = (c->regs[arg_y] > c->regs[arg_x]) ? 1 : 0;
c->regs[arg_x] = (c->regs[arg_y] - c->regs[arg_x]) & 0xFF;
} else if ((op & 0xF00F) == 0x800E) {
// SHL Vx
if ((c->regs[arg_x] & 0x80) == 0x80) {
c->regs[0xF] = 1;
} else {
c->regs[0xF] = 0;
}
c->regs[arg_x] = c->regs[arg_x] << 1;
} else if ((op & 0xF00F) == 0x9000) {
// SNE Vx, Vy
if (c->regs[arg_x] != c->regs[arg_y])
c->pc += 0x02;
} else if ((op & 0xF000) == 0xA000) {
// LD I, addr
c->reg_I = arg_nnn;
} else if ((op & 0xF000) == 0xB000) {
// JP V0, addr
c->pc = c->regs[0] + arg_nnn - 0x02;
} else if ((op & 0xF000) == 0xC000) {
// RND Vx, byte
c->regs[arg_x] = (rand() & 0xFF) & arg_kk;
} else if ((op & 0xF000)== 0xD000) {
// DRW Vx, Vy, nibble
uint8_t target_v_reg_x = arg_x;
uint8_t target_v_reg_y = arg_y;
uint8_t x_location = c->regs[target_v_reg_x];
uint8_t y_location = c->regs[target_v_reg_y];
uint8_t sprite_height = arg_n;
uint8_t pixel;
c->regs[0xF] = 0;
for (int y_coordinate = 0; y_coordinate < sprite_height; y_coordinate++) {
pixel = c->memory[c->reg_I + y_coordinate];
for (int x_coordinate = 0; x_coordinate < 8; x_coordinate++) {
if ((pixel & (0x80 >> x_coordinate)) != 0) {
uint8_t _y = y_location + y_coordinate;
uint8_t _x = x_location + x_coordinate;
if (c->display[_y * 64 + _x] == 1) {
c->regs[0xF] = 1;
}
c->display[_y * 64 + _x] ^= 1;
}
}
}
} else if ((op & 0xF0FF) == 0xE09E) {
// SKP Vx
if (c->keypad[c->regs[arg_x]] == 0x1)
c->pc += 0x2;
} else if ((op & 0xF0FF) == 0xE0A1) {
// SKNP Vx
if (c->keypad[c->regs[arg_x]] == 0x0)
c->pc += 0x2;
} else if ((op & 0xF0FF) == 0xF007) {
// LD Vx, DT
c->regs[arg_x] = c->DT;
} else if ((op & 0xF0FF) == 0xF00A) {
// LD Vx, K
// FIXME: implementar teclado
c->waiting_for_keypress = 0x1;
c->waiting_for_keypress_reg = arg_x;
printf("LD Vx, K ..... Aguardando keypress...\n");
} else if ((op & 0xF0FF) == 0xF015) {
// LD DT, Vx
c->DT = c->regs[arg_x];
} else if ((op & 0xF0FF) == 0xF018) {
// LD ST, Vx
c->ST = c->regs[arg_x];
} else if ((op & 0xF0FF) == 0xF01E) {
// ADD I, Vx
c->reg_I += c->regs[arg_x];
} else if ((op & 0xF0FF) == 0xF029) {
// LD F, Vx
c->reg_I = c->regs[arg_x] << 4;
} else if ((op & 0xF0FF) == 0xF033) {
// LD B, Vx
c->memory[c->reg_I] = c->regs[arg_x] / 100;
c->memory[c->reg_I+1] = (c->regs[arg_x] / 10) % 10;
c->memory[c->reg_I+2] = (c->regs[arg_x] % 100) % 10;
} else if ((op & 0xF0FF) == 0xF055) {
// LD [I], Vx
for (int i = 0; i <= arg_x; i++) {
c->memory[c->reg_I + i] = c->regs[i];
}
//c->reg_I += arg_x + 1;
} else if ((op & 0xF0FF) == 0xF065) {
// LD Vx, [I]
for (int i = 0; i <= arg_x; i++) {
c->regs[i] = c->memory[c->reg_I + i];
}
//c->reg_I += arg_x + 1;
}
c->pc += 0x02;
if (c->DT > 0) c->DT--;
if (c->ST > 0) c->ST--;
}
void Chip8_Render(Chip *c, SDL_Renderer *renderer) {
for (int y = 0; y < 32; y++) {
for (int x = 0; x < 64; x++) {
if (c->display[x + y * 64] > 0) {
SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
} else {
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
}
SDL_Rect r;
r.x = x * SCALE;
r.y = y * SCALE;
r.w = 1 * SCALE;
r.h = 1 * SCALE;
SDL_RenderFillRect(renderer, &r);
}
}
}
void Chip8_HandleKeyboard(Chip *c, int key, int down) {
uint8_t ch8_key;
switch (key) {
case SDLK_NUMLOCKCLEAR:
ch8_key = 0x1;
break;
case SDLK_KP_DIVIDE:
ch8_key = 0x2;
break;
case SDLK_KP_MULTIPLY:
ch8_key = 0x3;
break;
case SDLK_KP_MINUS:
ch8_key = 0xC;
break;
case SDLK_KP_7:
ch8_key = 0x4;
break;
case SDLK_KP_8:
ch8_key = 0x5;
break;
case SDLK_KP_9:
ch8_key = 0x6;
break;
case SDLK_KP_PLUS:
ch8_key = 0xD;
break;
case SDLK_KP_4:
ch8_key = 0x7;
break;
case SDLK_KP_5:
ch8_key = 0x8;
break;
case SDLK_KP_6:
ch8_key = 0x9;
break;
case SDLK_KP_COMMA:
ch8_key = 0xE;
break;
case SDLK_KP_1:
ch8_key = 0xA;
break;
case SDLK_KP_2:
ch8_key = 0x0;
break;
case SDLK_KP_3:
ch8_key = 0xB;
break;
case SDLK_KP_ENTER:
ch8_key = 0xF;
break;
default:
return;
}
if (c->waiting_for_keypress) {
c->waiting_for_keypress = false;
c->regs[c->waiting_for_keypress_reg] = ch8_key;
}
c->keypad[ch8_key] = (down > 0) ? true : false;
}