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add WebPDispatchAlphaToGreen() to dsp

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SSE2 version is 2.1x faster

This is used to transfer the alpha plane to green channel before lossless compression.

Change-Id: I01d9df0051c183b1ff5d6eb69961d4f43e33141a
This commit is contained in:
Pascal Massimino
2014-10-06 23:15:44 +02:00
parent 1bd4c2ad23
commit 2d9b0a4472
4 changed files with 51 additions and 13 deletions
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27
src/dsp/alpha_processing_sse2.c
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@ -72,6 +72,32 @@ static int DispatchAlpha(const uint8_t* alpha, int alpha_stride,
return (alpha_and != 0xff);
}
static void DispatchAlphaToGreen(const uint8_t* alpha, int alpha_stride,
int width, int height,
uint32_t* dst, int dst_stride) {
int i, j;
const __m128i zero = _mm_setzero_si128();
const int limit = width & ~15;
for (j = 0; j < height; ++j) {
for (i = 0; i < limit; i += 16) { // process 16 alpha bytes
const __m128i a0 = _mm_loadu_si128((__m128i*)&alpha[i]);
const __m128i a1 = _mm_unpacklo_epi8(zero, a0); // note the 'zero' first!
const __m128i b1 = _mm_unpackhi_epi8(zero, a0);
const __m128i a2_lo = _mm_unpacklo_epi16(a1, zero);
const __m128i b2_lo = _mm_unpacklo_epi16(b1, zero);
const __m128i a2_hi = _mm_unpackhi_epi16(a1, zero);
const __m128i b2_hi = _mm_unpackhi_epi16(b1, zero);
_mm_storeu_si128((__m128i*)&dst[i + 0], a2_lo);
_mm_storeu_si128((__m128i*)&dst[i + 4], a2_hi);
_mm_storeu_si128((__m128i*)&dst[i + 8], b2_lo);
_mm_storeu_si128((__m128i*)&dst[i + 12], b2_hi);
}
for (; i < width; ++i) dst[i] = alpha[i] << 8;
alpha += alpha_stride;
dst += dst_stride;
}
}
static int ExtractAlpha(const uint8_t* argb, int argb_stride,
int width, int height,
uint8_t* alpha, int alpha_stride) {
@ -264,6 +290,7 @@ void WebPInitAlphaProcessingSSE2(void) {
WebPMultRow = MultRow;
WebPApplyAlphaMultiply = ApplyAlphaMultiply;
WebPDispatchAlpha = DispatchAlpha;
WebPDispatchAlphaToGreen = DispatchAlphaToGreen;
WebPExtractAlpha = ExtractAlpha;
#endif
}