SameBoy/Core/camera.c

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2.2 KiB
C
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#include "camera.h"
static int8_t dither_random(uint8_t x, uint8_t y)
{
static bool once = false;
static int8_t random[128*112];
if (!once) {
unsigned int r = 0x1337c0de;
for (int i = 0; i < sizeof(random); i++) {
random[i] = r % 85 - 42;
r += 11;
r *= 25214903917;
}
once = true;
}
return random[x + y * 128];
}
uint8_t GB_camera_read_image(GB_gameboy_t *gb, uint16_t addr)
{
uint8_t tile_x = addr / 0x10 % 0x10;
uint8_t tile_y = addr / 0x10 / 0x10;
uint8_t y = ((addr >> 1) & 0x7) + tile_y * 8;
uint8_t bit = addr & 1;
uint8_t ret = 0;
for (uint8_t x = tile_x * 8; x < tile_x * 8 + 8; x++) {
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int color = gb->camera_get_pixel_callback? gb->camera_get_pixel_callback(gb, x,y) ^ 0xFF : (rand() & 0xFF);
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/* Dither using a deterministic random */
color += dither_random(x, y);
if (color > 255) {
color = 255;
}
else if (color < 0) {
color = 0;
}
ret <<= 1;
ret |= (color >> (6 + bit)) & 1;
}
return ret;
}
void GB_set_camera_get_pixel_callback(GB_gameboy_t *gb, GB_camera_get_pixel_callback_t callback)
{
gb->camera_get_pixel_callback = callback;
}
void GB_set_camera_update_request_callback(GB_gameboy_t *gb, GB_camera_update_request_callback_t callback)
{
gb->camera_update_request_callback = callback;
}
void GB_camera_updated(GB_gameboy_t *gb)
{
gb->camera_registers[0] = 0;
}
void GB_camera_write_register(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
{
addr &= 0x7F;
if (addr == 0) {
if ((value & 1) && gb->camera_update_request_callback) {
/* If no callback is set, ignore the write as if the camera is instantly done */
gb->camera_registers[0] = 1;
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gb->camera_update_request_callback(gb);
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}
}
else {
if (addr >= 0x36) {
GB_log(gb, "Wrote invalid camera register %02x: %2x\n", addr, value);
}
/* Todo: find out what these registers do */
gb->camera_registers[addr] = value;
}
}
uint8_t GB_camera_read_register(GB_gameboy_t *gb, uint16_t addr)
{
if ((addr & 0x7F) == 0) {
return gb->camera_registers[0];
}
return 0;
}