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Add a WebPExtractAlpha function to dsp

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This is the opposite of WebPDispatchAlpha

+ Implement the SSE2 version

Change-Id: I0c297309255f508c5261da8aad01f7e57f924d6c
This commit is contained in:
Pascal Massimino
2014-09-15 08:11:36 +02:00
parent 0716a98eb3
commit cddd334050
3 changed files with 73 additions and 1 deletions
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20
src/dsp/alpha_processing.c
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@ -303,9 +303,28 @@ static int DispatchAlpha(const uint8_t* alpha, int alpha_stride,
return (alpha_mask != 0xff);
}
static int ExtractAlpha(const uint8_t* argb, int argb_stride,
int width, int height,
uint8_t* alpha, int alpha_stride) {
uint8_t alpha_mask = 0xff;
int i, j;
for (j = 0; j < height; ++j) {
for (i = 0; i < width; ++i) {
const uint8_t alpha_value = argb[4 * i];
alpha[i] = alpha_value;
alpha_mask &= alpha_value;
}
argb += argb_stride;
alpha += alpha_stride;
}
return (alpha_mask == 0xff);
}
void (*WebPApplyAlphaMultiply)(uint8_t*, int, int, int, int);
void (*WebPApplyAlphaMultiply4444)(uint8_t*, int, int, int);
int (*WebPDispatchAlpha)(const uint8_t*, int, int, int, uint8_t*, int);
int (*WebPExtractAlpha)(const uint8_t*, int, int, int, uint8_t*, int);
//------------------------------------------------------------------------------
// Init function
@ -320,6 +339,7 @@ void WebPInitAlphaProcessing(void) {
WebPApplyAlphaMultiply = ApplyAlphaMultiply;
WebPApplyAlphaMultiply4444 = ApplyAlphaMultiply_16b;
WebPDispatchAlpha = DispatchAlpha;
WebPExtractAlpha = ExtractAlpha;
// If defined, use CPUInfo() to overwrite some pointers with faster versions.
if (VP8GetCPUInfo != NULL) {