diff options
| -rw-r--r-- | chip8.c | 22 | ||||
| -rw-r--r-- | chip8.h | 6 | ||||
| -rw-r--r-- | main.c | 6 |
3 files changed, 21 insertions, 13 deletions
@@ -3,7 +3,7 @@ uint16_t opcode; // 2 byte opcode uint8_t key[KEY_SIZE]; // hex key input uint32_t video[WIDTH*HEIGHT]; // video memory TODO: video should be 8 bit not 32 -uint8_t V[16]; // registers - 0x0 to 0xF +uint8_t V[REGISTER_COUNT]; // registers - 0x0 to 0xF uint16_t I; // special I register, stores addresses uint16_t PC; // program counter uint8_t SP; // stack pointer @@ -48,7 +48,7 @@ load_rom(char *rom) } /* read a maximum of MAX_ROM_SIZE bytes into memory starting after the reserved memory */ - fread(&memory[0x200], 1, MAX_ROM_SIZE, romfile); + fread(&memory[PROGRAM_START], 1, MAX_ROM_SIZE, romfile); fclose(romfile); return ret; @@ -58,13 +58,13 @@ void chip8_init() { /* clear everything and set sane defaults */ - memset(key, 0, sizeof(uint8_t) * 15); + memset(key, 0, sizeof(uint8_t) * KEY_SIZE); memset(video, 0, (WIDTH*HEIGHT) * sizeof(uint32_t)); - memset(V, 0, sizeof(uint8_t) * 16); + memset(V, 0, sizeof(uint8_t) * REGISTER_COUNT); memset(stack, 0, (STACK_SIZE) * sizeof(uint16_t)); memset(memory, 0, sizeof(uint8_t) * MEMORY_SIZE); - PC = 0x200; // set program counter to where roms are stored + PC = PROGRAM_START; // set program counter to where roms are stored opcode = 0; I = 0; SP = 0; @@ -75,16 +75,16 @@ chip8_init() /* load font into memory at 0x00: we have 0x00 to 0x1FF free for anything we want */ //TODO: add whole alphabet, then can write a rom to write strings or something - for (uint8_t i = 0; i < 80; i++) + for (uint8_t i = 0; i < FONT_BYTE_SIZE; i++) { - memory[0x0 + i] = chip8_fontset[i]; + memory[ + i] = chip8_fontset[i]; } uint8_t sinv[] = {0xBA, 0x7C, 0xD6, 0xFE, 0x54, 0xAA}; // temp - for (uint8_t i = 0; i < 6; i++) + for (uint8_t i = 0; i <= FONT_WIDTH; i++) { - memory[0x200+i] = sinv[i]; + memory[PROGRAM_START+i] = sinv[i]; } } @@ -103,7 +103,7 @@ chip8_draw_sprite(int startx, int starty, uint16_t mem, uint8_t size) /* loop through each byte from mem to mem+size */ byte = memory[mem+byteoffset]; int bit = 0; - for (mask = 0x80; mask != 0; mask >>= 1) + for (mask = BYTE_MASK; mask != 0; mask >>= 1) { if (byte & mask) { @@ -113,7 +113,7 @@ chip8_draw_sprite(int startx, int starty, uint16_t mem, uint8_t size) /* if the video bit is already set, we need to set the collision register */ V[0xF] = 1; } - video[pixel] ^= 0xFFFFFF; + video[pixel] ^= PIXEL_COLOR; } bit++; } @@ -12,8 +12,14 @@ #define HEIGHT 32 #define KEY_SIZE 15 #define MEMORY_SIZE 4096 +#define REGISTER_COUNT 16 #define STACK_SIZE 16 #define MAX_ROM_SIZE 0x1000 - 0x200 // memory size - reserved memory +#define PROGRAM_START 0x200 +#define FONT_WIDTH 5 +#define FONT_BYTE_SIZE 80 +#define BYTE_MASK 0x80 +#define PIXEL_COLOR 0xFFFFFF int load_rom(); void chip8_init(); @@ -45,7 +45,6 @@ quit() SDL_DestroyRenderer(renderer); SDL_DestroyWindow(window); SDL_Quit(); - } void @@ -72,7 +71,7 @@ toggle_pixel(int x, int y) // TODO: clean uint32_t dos = video[WIDTH*y+x]; if (dos <= 0) - video[WIDTH*y+x] = (255<<16)|(255<<8)|255; + video[WIDTH*y+x] = PIXEL_COLOR; else video[WIDTH*y+x] = 0; } @@ -207,7 +206,10 @@ int main(int argc, char *argv[]) chip8_cycle(); if (draw_flag) + { update_video(); + draw_flag = 0; + } frame_time = SDL_GetTicks() - frame_start; if (frame_delay > frame_time) |