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Add a fast path for ARGB888->(A)BGR888 blending with pixel alpha

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This commit is contained in:
Cameron Cawley 2021-09-28 18:07:22 +01:00 committed by Sam Lantinga
parent 8b23029d23
commit c270949b5e
1 changed files with 61 additions and 0 deletions
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61
src/video/SDL_blit_A.c
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@ -575,6 +575,61 @@ BlitRGBtoRGBPixelAlpha(SDL_BlitInfo * info)
}
}
/* fast ARGB888->(A)BGR888 blending with pixel alpha */
static void
BlitRGBtoBGRPixelAlpha(SDL_BlitInfo * info)
{
int width = info->dst_w;
int height = info->dst_h;
Uint32 *srcp = (Uint32 *) info->src;
int srcskip = info->src_skip >> 2;
Uint32 *dstp = (Uint32 *) info->dst;
int dstskip = info->dst_skip >> 2;
while (height--) {
/* *INDENT-OFF* */
DUFFS_LOOP4({
Uint32 dalpha;
Uint32 d;
Uint32 s1;
Uint32 d1;
Uint32 s = *srcp;
Uint32 alpha = s >> 24;
/* FIXME: Here we special-case opaque alpha since the
compositioning used (>>8 instead of /255) doesn't handle
it correctly. Also special-case alpha=0 for speed?
Benchmark this! */
if (alpha) {
/*
* take out the middle component (green), and process
* the other two in parallel. One multiply less.
*/
s1 = s & 0xff00ff;
s1 = (s1 >> 16) | (s1 << 16);
s &= 0xff00;
if (alpha == SDL_ALPHA_OPAQUE) {
*dstp = 0xff000000 | s | s1;
} else {
d = *dstp;
dalpha = d >> 24;
d1 = d & 0xff00ff;
d1 = (d1 + ((s1 - d1) * alpha >> 8)) & 0xff00ff;
d &= 0xff00;
d = (d + ((s - d) * alpha >> 8)) & 0xff00;
dalpha = alpha + (dalpha * (alpha ^ 0xFF) >> 8);
*dstp = d1 | d | (dalpha << 24);
}
}
++srcp;
++dstp;
}, width);
/* *INDENT-ON* */
srcp += srcskip;
dstp += dstskip;
}
}
#ifdef __3dNOW__
/* fast (as in MMX with prefetch) ARGB888->(A)RGB888 blending with pixel alpha */
static void
@ -1407,6 +1462,12 @@ SDL_CalculateBlitA(SDL_Surface * surface)
#endif
return BlitRGBtoRGBPixelAlpha;
}
} else if (sf->Rmask == df->Bmask
&& sf->Gmask == df->Gmask
&& sf->Bmask == df->Rmask && sf->BytesPerPixel == 4) {
if (sf->Amask == 0xff000000) {
return BlitRGBtoBGRPixelAlpha;
}
}
return BlitNtoNPixelAlpha;