blues/decode.c

33 lines
874 B
C

#include "decode.h"
void decode_ega_spr(const uint8_t *src, int src_pitch, int w, int h, uint8_t *dst, int dst_pitch, int dst_x, int dst_y, int xflip) {
assert((src_pitch & 7) == 0);
src_pitch /= 8;
assert((w & 7) == 0);
w /= 8;
const int bitplane_size = w * h;
for (int y = 0; y < h; ++y) {
const int y_offset = dst_y + y;
for (int x = 0; x < w; ++x) {
for (int i = 0; i < 8; ++i) {
int color = 0;
const int mask = 1 << (7 - i);
for (int bit = 0; bit < 4; ++bit) {
if (src[bit * bitplane_size] & mask) {
color |= 1 << (3 - bit);
}
}
if (color != 0) {
const int x_offset = dst_x + (xflip ? (w * 8 - x * 8 - i) : (x * 8 + i));
if (x_offset >= 0 && x_offset < 320 && y_offset >= 0 && y_offset < 200) {
dst[y_offset * dst_pitch + x_offset] = color;
}
}
}
++src;
}
src += src_pitch - w;
}
}