diff options
Diffstat (limited to 'chip8.c')
| -rw-r--r-- | chip8.c | 30 |
1 files changed, 17 insertions, 13 deletions
@@ -79,10 +79,17 @@ chip8_init() { memory[0x0 + i] = chip8_fontset[i]; } + + uint8_t sinv[] = {0xBA, 0x7C, 0xD6, 0xFE, 0x54, 0xAA}; + // temp + for (uint8_t i = 0; i < 6; i++) + { + memory[0x200+i] = sinv[i]; + } } void -chip8_draw_sprite(int startx, int starty, uint8_t mem, uint8_t size) +chip8_draw_sprite(int startx, int starty, uint16_t mem, uint8_t size) { /* * draw sprite located at loc of height size at startx,starty @@ -90,7 +97,7 @@ chip8_draw_sprite(int startx, int starty, uint8_t mem, uint8_t size) uint8_t byte = 0; uint8_t mask = 0x1; - uint8_t destbit = 0x0; + V[0xF] = 0; /* set collision register to 0 */ for (uint8_t byteoffset = 0; byteoffset < size; byteoffset++) { /* loop through each byte from mem to mem+size */ @@ -98,21 +105,18 @@ chip8_draw_sprite(int startx, int starty, uint8_t mem, uint8_t size) int bit = 0; for (mask = 0x80; mask != 0; mask >>= 1) { - if (byte&mask) - { - destbit = 1; - video[WIDTH*starty+(startx+bit)] = 0xFFFFFF; - } - else + if (byte & mask) { - destbit = 0; - video[WIDTH*starty+(startx+bit)] = 0x0; + uint32_t pixel = WIDTH*(starty%HEIGHT)+((startx%WIDTH)+bit); + if (video[pixel] != 0) + { + /* if the video bit is already set, we need to set the collision register */ + V[0xF] = 1; + } + video[pixel] ^= 0xFFFFFF; } - printf("%d", destbit); bit++; } starty++; - puts(""); } - puts("---"); } |