int
main(void)
{
int i, j;
int err, maxerr, maxi;
int nerr, ntot;
nerr = 0;
ntot = 0;
maxerr = 0;
maxi = -1;
for(i = 0; i < 256; i++){
for(j = 0; j < 256; j++){
if((err = div255(i*j) - (i*j)/255) != 0){
err = err >= 0 ? err : -err;
if(err > maxerr){
maxerr = err;
maxi = i*j;
}
nerr++;
printf("error %d/255 = %d, need %d\n", i*j, div255(i*j), (i*j)/255);
}
ntot++;
}
}
printf("%d errors from %d total, maximum error: %d, %d/255 = %d, should be %d\n", nerr, ntot, maxerr, maxi, div255(maxi), maxi/255);
return 0;
}
static void assRender(VSFrameRef *dst, VSFrameRef *alpha, const VSAPI *vsapi,
ASS_Image *img)
{
uint8_t *planes[4];
int strides[4], p;
for(p = 0; p < 4; p++) {
VSFrameRef *fr = p == 3 ? alpha : dst;
planes[p] = vsapi->getWritePtr(fr, p % 3);
strides[p] = vsapi->getStride(fr, p % 3);
memset(planes[p], 0, strides[p] * vsapi->getFrameHeight(fr, p % 3));
}
while(img) {
uint8_t *dstp[4], *alphap, *sp, color[4];
uint16_t outa;
int x, y, k;
if(img->w == 0 || img->h == 0) {
img = img->next;
continue;
}
color[0] = _r(img->color);
color[1] = _g(img->color);
color[2] = _b(img->color);
color[3] = _a(img->color);
dstp[0] = planes[0] + (strides[0] * img->dst_y) + img->dst_x;
dstp[1] = planes[1] + (strides[1] * img->dst_y) + img->dst_x;
dstp[2] = planes[2] + (strides[2] * img->dst_y) + img->dst_x;
dstp[3] = planes[3] + (strides[3] * img->dst_y) + img->dst_x;
alphap = dstp[3];
sp = img->bitmap;
for(y = 0; y < img->h; y++) {
for(x = 0; x < img->w; x++) {
k = div255(sp[x] * color[3]);
outa = k * 255 + (alphap[x] * (255 - k));
if(outa != 0) {
dstp[0][x] = blend(k, color[0], alphap[x], dstp[0][x], outa);
dstp[1][x] = blend(k, color[1], alphap[x], dstp[1][x], outa);
dstp[2][x] = blend(k, color[2], alphap[x], dstp[2][x], outa);
dstp[3][x] = div255(outa);
}
}
dstp[0] += strides[0];
dstp[1] += strides[1];
dstp[2] += strides[2];
dstp[3] += strides[3];
alphap += strides[3];
sp += img->stride;
}
img = img->next;
}
}
