mirror of
https://github.com/webmproject/libwebp.git
synced 2025-07-15 21:39:59 +02:00
Add a WebPExtractAlpha function to dsp
This is the opposite of WebPDispatchAlpha + Implement the SSE2 version Change-Id: I0c297309255f508c5261da8aad01f7e57f924d6c
This commit is contained in:
@ -72,6 +72,51 @@ static int DispatchAlpha(const uint8_t* alpha, int alpha_stride,
|
||||
return (alpha_and != 0xff);
|
||||
}
|
||||
|
||||
static int ExtractAlpha(const uint8_t* argb, int argb_stride,
|
||||
int width, int height,
|
||||
uint8_t* alpha, int alpha_stride) {
|
||||
// alpha_and stores an 'and' operation of all the alpha[] values. The final
|
||||
// value is not 0xff if any of the alpha[] is not equal to 0xff.
|
||||
uint32_t alpha_and = 0xff;
|
||||
int i, j;
|
||||
const __m128i a_mask = _mm_set1_epi32(0xffu); // to preserve alpha
|
||||
const __m128i all_0xff = _mm_set_epi32(0, 0, ~0u, ~0u);
|
||||
__m128i all_alphas = all_0xff;
|
||||
|
||||
// We must be able to access 3 extra bytes after the last written byte
|
||||
// 'src[4 * width - 4]', because we don't know if alpha is the first or the
|
||||
// last byte of the quadruplet.
|
||||
const int limit = (width - 1) & ~7;
|
||||
|
||||
for (j = 0; j < height; ++j) {
|
||||
const __m128i* src = (const __m128i*)argb;
|
||||
for (i = 0; i < limit; i += 8) {
|
||||
// load 32 argb bytes
|
||||
const __m128i a0 = _mm_loadu_si128(src + 0);
|
||||
const __m128i a1 = _mm_loadu_si128(src + 1);
|
||||
const __m128i b0 = _mm_and_si128(a0, a_mask);
|
||||
const __m128i b1 = _mm_and_si128(a1, a_mask);
|
||||
const __m128i c0 = _mm_packs_epi32(b0, b1);
|
||||
const __m128i d0 = _mm_packus_epi16(c0, c0);
|
||||
// store
|
||||
_mm_storel_epi64((__m128i*)&alpha[i], d0);
|
||||
// accumulate eight alpha 'and' in parallel
|
||||
all_alphas = _mm_and_si128(all_alphas, d0);
|
||||
src += 2;
|
||||
}
|
||||
for (; i < width; ++i) {
|
||||
const uint32_t alpha_value = argb[4 * i];
|
||||
alpha[i] = alpha_value;
|
||||
alpha_and &= alpha_value;
|
||||
}
|
||||
argb += argb_stride;
|
||||
alpha += alpha_stride;
|
||||
}
|
||||
// Combine the eight alpha 'and' into a 8-bit mask.
|
||||
alpha_and &= _mm_movemask_epi8(_mm_cmpeq_epi8(all_alphas, all_0xff));
|
||||
return (alpha_and == 0xff);
|
||||
}
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
// Non-dither premultiplied modes
|
||||
|
||||
@ -219,5 +264,6 @@ void WebPInitAlphaProcessingSSE2(void) {
|
||||
WebPMultRow = MultRow;
|
||||
WebPApplyAlphaMultiply = ApplyAlphaMultiply;
|
||||
WebPDispatchAlpha = DispatchAlpha;
|
||||
WebPExtractAlpha = ExtractAlpha;
|
||||
#endif
|
||||
}
|
||||
|
Reference in New Issue
Block a user