diff options
| -rw-r--r-- | chip8.c | 49 | ||||
| -rw-r--r-- | chip8.h | 2 |
2 files changed, 47 insertions, 4 deletions
@@ -1,5 +1,6 @@ #include "chip8.h" +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 @@ -8,6 +9,30 @@ uint16_t PC; // program counter uint8_t SP; // stack pointer uint16_t stack[STACK_SIZE]; // stack, for address storage when using subroutines, maximum of 16 levels of nested subroutines uint8_t memory[MEMORY_SIZE]; // 4KB of program memory +int draw_flag; // draw flag, when 1 the screen will be drawn +uint8_t delay_timer; // delay timer, decremented by one at 60hz, at 0 do nothing +uint8_t sound_timer; // sound timer, decremented by one at 60hz, while it is > 0 a beep is played + +/* 0 - F hexidecimal font as required by the chip8 spec */ +uint8_t chip8_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 +}; int load_rom(char *rom) @@ -32,10 +57,26 @@ load_rom(char *rom) void chip8_init() { - /* clear everything */ - memset(key, 0, 15); + /* clear everything and set sane defaults */ + memset(key, 0, sizeof(uint8_t) * 15); memset(video, 0, (WIDTH*HEIGHT) * sizeof(uint32_t)); - memset(V, 0, 16); + memset(V, 0, sizeof(uint8_t) * 16); memset(stack, 0, (STACK_SIZE) * sizeof(uint16_t)); - memset(memory, 0, MEMORY_SIZE); + memset(memory, 0, sizeof(uint8_t) * MEMORY_SIZE); + + PC = 0x200; // set program counter to where roms are stored + opcode = 0; + I = 0; + SP = 0; + draw_flag = 1; // draw by default i guess + delay_timer = 0; + sound_timer = 0; + srand(time(NULL)); // seed rng + + /* 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++) + { + memory[0x0 + i] = chip8_fontset[i]; + } } @@ -2,9 +2,11 @@ #define CHIP8_H #include <stdio.h> +#include <stdlib.h> #include <stdint.h> #include <string.h> #include <errno.h> +#include <time.h> #define WIDTH 64 #define HEIGHT 32 |