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#include <stdio.h>
#include <stdlib.h>
#include <SDL2/SDL.h>
#include "chip8.h"
/* references
* https://austinmorlan.com/posts/chip8_emulator/
* http://www.multigesture.net/articles/how-to-write-an-emulator-chip-8-interpreter/
* http://mattmik.com/files/chip8/mastering/chip8.html (lots of info)
* http://devernay.free.fr/hacks/chip8/C8TECH10.HTM#0.1
* http://www.emulator101.com/chip-8-sprites.html
*/
#define VIDEO_SCALE 5
SDL_Window *window;
SDL_Renderer *renderer;
SDL_Texture *texture;
void init_video();
void update_video();
void toggle_pixel(int x, int y);
void quit();
void usage(char *);
void handle_key_down(int keycode);
void handle_key_up(int keycode);
uint8_t get_chip8_key(int keycode);
extern uint32_t video[WIDTH*HEIGHT];
extern int draw_flag;
extern uint8_t key[KEY_SIZE];
void
usage(char *program)
{
printf("usage: %s [romfile]\n", program);
}
void
quit()
{
SDL_DestroyTexture(texture);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
}
void
init_video()
{
SDL_Init(SDL_INIT_VIDEO);
window = SDL_CreateWindow("chip8 interpreter", 0, 0, WIDTH*VIDEO_SCALE, HEIGHT*VIDEO_SCALE, SDL_WINDOW_SHOWN);
renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA32, SDL_TEXTUREACCESS_STREAMING, WIDTH, HEIGHT);
}
void
update_video()
{
SDL_UpdateTexture(texture, NULL, video, sizeof(video[0])*WIDTH);
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, texture, NULL, NULL);
SDL_RenderPresent(renderer);
}
void
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;
else
video[WIDTH*y+x] = 0;
}
void
handle_key_down(int keycode)
{
uint8_t k = get_chip8_key(keycode);
if (k > 0xF) return; /* unknown key */
key[k] = 1;
}
void
handle_key_up(int keycode)
{
uint8_t k = get_chip8_key(keycode);
if (k > 0xF) return; /* unknown key */
key[k] = 0;
}
uint8_t
get_chip8_key(int keycode)
{
switch(keycode)
{
case SDLK_1: return 0x1;
case SDLK_2: return 0x2;
case SDLK_3: return 0x3;
case SDLK_4: return 0xC;
case SDLK_q: return 0x4;
case SDLK_w: return 0x5;
case SDLK_e: return 0x6;
case SDLK_r: return 0xD;
case SDLK_a: return 0x7;
case SDLK_s: return 0x8;
case SDLK_d: return 0x9;
case SDLK_f: return 0xE;
case SDLK_z: return 0xA;
case SDLK_x: return 0x0;
case SDLK_c: return 0xB;
case SDLK_v: return 0xF;
default: return 0xFF;
}
}
int main(int argc, char *argv[])
{
if (argc < 2)
{
usage(argv[0]);
exit(EXIT_FAILURE);
}
if (!load_rom(argv[1]))
{
fprintf(stderr, "cannot start interpreter\n");
exit(EXIT_FAILURE);
}
chip8_init();
init_video();
const int fps = 60;
const int frame_delay = 1000/fps;
uint32_t frame_start;
uint32_t frame_time;
int do_quit = 0;
chip8_draw_sprite(0, 0, 0xD*5, 0x5);
chip8_draw_sprite(5, 0, 0xE*5, 0x5);
chip8_draw_sprite(10, 0, 0xA*5, 0x5);
chip8_draw_sprite(15, 0, 0xD*5, 0x5);
chip8_draw_sprite(20, 0, 0xB*5, 0x5);
chip8_draw_sprite(25, 0, 0xE*5, 0x5);
chip8_draw_sprite(30, 0, 0xE*5, 0x5);
chip8_draw_sprite(35, 0, 0xf*5, 0x5);
chip8_draw_sprite(0, 9, 0xD*5, 0x5);
chip8_draw_sprite(5, 9, 0xE*5, 0x5);
chip8_draw_sprite(10, 9, 0xA*5, 0x5);
chip8_draw_sprite(15, 9, 0xD*5, 0x5);
chip8_draw_sprite(20, 9, 0xB*5, 0x5);
chip8_draw_sprite(25, 9, 0xE*5, 0x5);
chip8_draw_sprite(30, 9, 0xE*5, 0x5);
chip8_draw_sprite(35, 9, 0xf*5, 0x5);
chip8_draw_sprite(0, 20, 0x200, 0x6);
chip8_draw_sprite(8, 20, 0x200, 0x6);
chip8_draw_sprite(16, 20, 0x200, 0x6);
chip8_draw_sprite(18, 20, 0x200, 0x6);
chip8_draw_sprite(61, 25, 0x200, 0x6);
chip8_draw_sprite(50, 30, 0x200, 0x6);
SDL_Event e;
while(!do_quit)
{
frame_start = SDL_GetTicks();
// logic
while (SDL_PollEvent(&e) != 0)
{
switch (e.type)
{
case SDL_QUIT:
do_quit = 1;
break;
case SDL_KEYDOWN:
{
switch(e.key.keysym.sym)
{
case SDLK_ESCAPE:
do_quit = 1;
break;
default:
handle_key_down(e.key.keysym.sym);
break;
}
break;
}
case SDL_KEYUP:
handle_key_up(e.key.keysym.sym);
break;
default: break;
}
}
chip8_cycle();
if (draw_flag)
update_video();
frame_time = SDL_GetTicks() - frame_start;
if (frame_delay > frame_time)
{
SDL_Delay(frame_delay - frame_time);
}
}
quit();
return EXIT_SUCCESS;
}
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