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https://github.com/webmproject/libwebp.git
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SSE2: 30% faster ApplyAlphaMultiply()
and 15% faster MultARGBRow()
by switching to formulae:
X / 255 = (X + 1 + (X >> 8)) >> 8 for any 16bit value X.
(X / 255 + .5) = (XX + (XX >> 8)) >> 8, with XX = X + 128
Change-Id: Ia4a7408aee74d7f61b58f5dff304d05546c04e81
This commit is contained in:
Pascal Massimino
parent
f44acd253b
commit
28fe054e73
@ -151,45 +151,40 @@ static int ExtractAlpha(const uint8_t* argb, int argb_stride,
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// We can't use a 'const int' for the SHUFFLE value, because it has to be an
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// immediate in the _mm_shufflexx_epi16() instruction. We really need a macro.
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#define APPLY_ALPHA(RGBX, SHUFFLE, MASK, MULT) do { \
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const __m128i argb0 = _mm_loadl_epi64((__m128i*)&(RGBX)); \
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const __m128i argb1 = _mm_unpacklo_epi8(argb0, zero); \
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const __m128i alpha0 = _mm_and_si128(argb1, MASK); \
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const __m128i alpha1 = _mm_shufflelo_epi16(alpha0, SHUFFLE); \
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const __m128i alpha2 = _mm_shufflehi_epi16(alpha1, SHUFFLE); \
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/* alpha2 = [0 a0 a0 a0][0 a1 a1 a1] */ \
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const __m128i scale0 = _mm_mullo_epi16(alpha2, MULT); \
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const __m128i scale1 = _mm_mulhi_epu16(alpha2, MULT); \
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const __m128i argb2 = _mm_mulhi_epu16(argb1, scale0); \
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const __m128i argb3 = _mm_mullo_epi16(argb1, scale1); \
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const __m128i argb4 = _mm_adds_epu16(argb2, argb3); \
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const __m128i argb5 = _mm_srli_epi16(argb4, 7); \
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const __m128i argb6 = _mm_or_si128(argb5, alpha0); \
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const __m128i argb7 = _mm_packus_epi16(argb6, zero); \
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_mm_storel_epi64((__m128i*)&(RGBX), argb7); \
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// We use: v / 255 = (v + 1 + (v >> 8)) >> 8, where v = alpha * {r,g,b} is
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// a 16bit value.
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#define APPLY_ALPHA(RGBX, SHUFFLE) do { \
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const __m128i argb0 = _mm_loadl_epi64((const __m128i*)&(RGBX)); \
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const __m128i argb1 = _mm_unpacklo_epi8(argb0, zero); \
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const __m128i alpha0 = _mm_or_si128(argb1, kMask); \
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const __m128i alpha1 = _mm_shufflelo_epi16(alpha0, SHUFFLE); \
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const __m128i alpha2 = _mm_shufflehi_epi16(alpha1, SHUFFLE); \
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/* alpha2 = [ff a0 a0 a0][ff a1 a1 a1] */ \
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const __m128i A0 = _mm_mullo_epi16(alpha2, argb1); \
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const __m128i A1 = _mm_srli_epi16(A0, 8); \
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const __m128i A2 = _mm_add_epi16(A1, A0); \
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const __m128i A3 = _mm_add_epi16(A2, one); \
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const __m128i A4 = _mm_srli_epi16(A3, 8); \
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const __m128i A5 = _mm_packus_epi16(A4, zero); \
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_mm_storel_epi64((__m128i*)&(RGBX), A5); \
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} while (0)
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static void ApplyAlphaMultiply(uint8_t* rgba, int alpha_first,
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int w, int h, int stride) {
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static void ApplyAlphaMultiply_SSE2(uint8_t* rgba, int alpha_first,
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int w, int h, int stride) {
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const __m128i zero = _mm_setzero_si128();
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const __m128i one = _mm_set1_epi16(1);
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const __m128i kMask = _mm_set_epi16(0, 0xff, 0xff, 0, 0, 0xff, 0xff, 0);
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const int kSpan = 2;
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const int w2 = w & ~(kSpan - 1);
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while (h-- > 0) {
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uint32_t* const rgbx = (uint32_t*)rgba;
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int i;
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if (!alpha_first) {
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const __m128i kMask = _mm_set_epi16(0xff, 0, 0, 0, 0xff, 0, 0, 0);
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const __m128i kMult =
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_mm_set_epi16(0, 0x8081, 0x8081, 0x8081, 0, 0x8081, 0x8081, 0x8081);
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for (i = 0; i < w2; i += kSpan) {
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APPLY_ALPHA(rgbx[i], _MM_SHUFFLE(0, 3, 3, 3), kMask, kMult);
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for (i = 0; i + kSpan <= w; i += kSpan) {
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APPLY_ALPHA(rgbx[i], _MM_SHUFFLE(2, 3, 3, 3));
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}
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} else {
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const __m128i kMask = _mm_set_epi16(0, 0, 0, 0xff, 0, 0, 0, 0xff);
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const __m128i kMult =
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_mm_set_epi16(0x8081, 0x8081, 0x8081, 0, 0x8081, 0x8081, 0x8081, 0);
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for (i = 0; i < w2; i += kSpan) {
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APPLY_ALPHA(rgbx[i], _MM_SHUFFLE(0, 0, 0, 3), kMask, kMult);
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for (i = 0; i + kSpan <= w; i += kSpan) {
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APPLY_ALPHA(rgbx[i], _MM_SHUFFLE(0, 0, 0, 1));
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}
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}
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// Finish with left-overs.
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@ -213,45 +208,37 @@ static void ApplyAlphaMultiply(uint8_t* rgba, int alpha_first,
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// -----------------------------------------------------------------------------
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// Apply alpha value to rows
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// We use: kINV255 = (1 << 24) / 255 = 0x010101
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// So: a * kINV255 = (a << 16) | [(a << 8) | a]
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// -> _mm_mulhi_epu16() takes care of the (a<<16) part,
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// and _mm_mullo_epu16(a * 0x0101,...) takes care of the "(a << 8) | a" one.
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static void MultARGBRow(uint32_t* const ptr, int width, int inverse) {
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static void MultARGBRow_SSE2(uint32_t* const ptr, int width, int inverse) {
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int x = 0;
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if (!inverse) {
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const int kSpan = 2;
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const __m128i zero = _mm_setzero_si128();
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const __m128i kRound =
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_mm_set_epi16(0, 1 << 7, 1 << 7, 1 << 7, 0, 1 << 7, 1 << 7, 1 << 7);
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const __m128i kMult =
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_mm_set_epi16(0, 0x0101, 0x0101, 0x0101, 0, 0x0101, 0x0101, 0x0101);
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const __m128i kOne64 = _mm_set_epi16(1u << 8, 0, 0, 0, 1u << 8, 0, 0, 0);
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const int w2 = width & ~(kSpan - 1);
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for (x = 0; x < w2; x += kSpan) {
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const __m128i argb0 = _mm_loadl_epi64((__m128i*)&ptr[x]);
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const __m128i argb1 = _mm_unpacklo_epi8(argb0, zero);
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const __m128i tmp0 = _mm_shufflelo_epi16(argb1, _MM_SHUFFLE(3, 3, 3, 3));
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const __m128i tmp1 = _mm_shufflehi_epi16(tmp0, _MM_SHUFFLE(3, 3, 3, 3));
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const __m128i tmp2 = _mm_srli_epi64(tmp1, 16);
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const __m128i scale0 = _mm_mullo_epi16(tmp1, kMult);
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const __m128i scale1 = _mm_or_si128(tmp2, kOne64);
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const __m128i argb2 = _mm_mulhi_epu16(argb1, scale0);
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const __m128i argb3 = _mm_mullo_epi16(argb1, scale1);
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const __m128i argb4 = _mm_adds_epu16(argb2, argb3);
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const __m128i argb5 = _mm_adds_epu16(argb4, kRound);
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const __m128i argb6 = _mm_srli_epi16(argb5, 8);
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const __m128i argb7 = _mm_packus_epi16(argb6, zero);
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_mm_storel_epi64((__m128i*)&ptr[x], argb7);
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const __m128i k128 = _mm_set1_epi16(128);
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const __m128i kMask = _mm_set_epi16(0, 0xff, 0, 0, 0, 0xff, 0, 0);
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for (x = 0; x + kSpan <= width; x += kSpan) {
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// To compute 'result = (int)(a * x / 255. + .5)', we use:
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// tmp = a * v + 128, result = (tmp + (tmp >> 8)) >> 8
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const __m128i A0 = _mm_loadl_epi64((const __m128i*)&ptr[x]);
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const __m128i A1 = _mm_unpacklo_epi8(A0, zero);
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const __m128i A2 = _mm_or_si128(A1, kMask);
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const __m128i A3 = _mm_shufflelo_epi16(A2, _MM_SHUFFLE(2, 3, 3, 3));
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const __m128i A4 = _mm_shufflehi_epi16(A3, _MM_SHUFFLE(2, 3, 3, 3));
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// here, A4 = [ff a0 a0 a0][ff a1 a1 a1]
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const __m128i A5 = _mm_mullo_epi16(A4, A1);
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const __m128i A6 = _mm_add_epi16(A5, k128);
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const __m128i A7 = _mm_srli_epi16(A6, 8);
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const __m128i A8 = _mm_add_epi16(A7, A6);
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const __m128i A9 = _mm_srli_epi16(A8, 8);
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const __m128i A10 = _mm_packus_epi16(A9, zero);
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_mm_storel_epi64((__m128i*)&ptr[x], A10);
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}
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}
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width -= x;
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if (width > 0) WebPMultARGBRowC(ptr + x, width, inverse);
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}
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static void MultRow(uint8_t* const ptr, const uint8_t* const alpha,
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int width, int inverse) {
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static void MultRow_SSE2(uint8_t* const ptr, const uint8_t* const alpha,
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int width, int inverse) {
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int x = 0;
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if (!inverse) {
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const int kSpan = 8;
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@ -283,9 +270,9 @@ static void MultRow(uint8_t* const ptr, const uint8_t* const alpha,
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extern void WebPInitAlphaProcessingSSE2(void);
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WEBP_TSAN_IGNORE_FUNCTION void WebPInitAlphaProcessingSSE2(void) {
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WebPMultARGBRow = MultARGBRow;
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WebPMultRow = MultRow;
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WebPApplyAlphaMultiply = ApplyAlphaMultiply;
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WebPMultARGBRow = MultARGBRow_SSE2;
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WebPMultRow = MultRow_SSE2;
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WebPApplyAlphaMultiply = ApplyAlphaMultiply_SSE2;
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WebPDispatchAlpha = DispatchAlpha;
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WebPDispatchAlphaToGreen = DispatchAlphaToGreen;
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WebPExtractAlpha = ExtractAlpha;
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