/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include"Swizzle.h"
#include <emmintrin.h>
namespace mozilla::gfx {
// Load 1-3 pixels into a 4 pixel vector. static MOZ_ALWAYS_INLINE __m128i LoadRemainder_SSE2(const uint8_t* aSrc,
size_t aLength) {
__m128i px; if (aLength >= 2) { // Load first 2 pixels
px = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(aSrc)); // Load third pixel if (aLength >= 3) {
px = _mm_unpacklo_epi64(
px,
_mm_cvtsi32_si128(*reinterpret_cast<const uint32_t*>(aSrc + 2 * 4)));
}
} else { // Load single pixel
px = _mm_cvtsi32_si128(*reinterpret_cast<const uint32_t*>(aSrc));
} return px;
}
// Store 1-3 pixels from a vector into memory without overwriting. static MOZ_ALWAYS_INLINE void StoreRemainder_SSE2(uint8_t* aDst, size_t aLength, const __m128i& aSrc) { if (aLength >= 2) { // Store first 2 pixels
_mm_storel_epi64(reinterpret_cast<__m128i*>(aDst), aSrc); // Store third pixel if (aLength >= 3) {
*reinterpret_cast<uint32_t*>(aDst + 2 * 4) =
_mm_cvtsi128_si32(_mm_srli_si128(aSrc, 2 * 4));
}
} else { // Store single pixel
*reinterpret_cast<uint32_t*>(aDst) = _mm_cvtsi128_si32(aSrc);
}
}
// Premultiply vector of 4 pixels using splayed math. template <bool aSwapRB, bool aOpaqueAlpha> static MOZ_ALWAYS_INLINE __m128i PremultiplyVector_SSE2(const __m128i& aSrc) { // Isolate R and B with mask. const __m128i mask = _mm_set1_epi32(0x00FF00FF);
__m128i rb = _mm_and_si128(mask, aSrc); // Swap R and B if necessary. if (aSwapRB) {
rb = _mm_shufflelo_epi16(rb, _MM_SHUFFLE(2, 3, 0, 1));
rb = _mm_shufflehi_epi16(rb, _MM_SHUFFLE(2, 3, 0, 1));
} // Isolate G and A by shifting down to bottom of word.
__m128i ga = _mm_srli_epi16(aSrc, 8);
// Duplicate alphas to get vector of A1 A1 A2 A2 A3 A3 A4 A4
__m128i alphas = _mm_shufflelo_epi16(ga, _MM_SHUFFLE(3, 3, 1, 1));
alphas = _mm_shufflehi_epi16(alphas, _MM_SHUFFLE(3, 3, 1, 1));
// If format is not opaque, force A to 255 so that A*alpha/255 = alpha if (!aOpaqueAlpha) {
ga = _mm_or_si128(ga, _mm_set1_epi32(0x00FF0000));
} // ga = ga*a + 255; ga += ga >> 8;
ga = _mm_add_epi16(_mm_mullo_epi16(ga, alphas), mask);
ga = _mm_add_epi16(ga, _mm_srli_epi16(ga, 8)); // If format is opaque, force output A to be 255. if (aOpaqueAlpha) {
ga = _mm_or_si128(ga, _mm_set1_epi32(0xFF000000));
}
// Combine back to final pixel with (rb >> 8) | (ga & 0xFF00FF00)
rb = _mm_srli_epi16(rb, 8);
ga = _mm_andnot_si128(mask, ga); return _mm_or_si128(rb, ga);
}
// Premultiply vector of aAlignedRow + aRemainder pixels. template <bool aSwapRB, bool aOpaqueAlpha> static MOZ_ALWAYS_INLINE void PremultiplyChunk_SSE2(const uint8_t*& aSrc,
uint8_t*& aDst,
int32_t aAlignedRow,
int32_t aRemainder) { // Process all 4-pixel chunks as one vector. for (const uint8_t* end = aSrc + aAlignedRow; aSrc < end;) {
__m128i px = _mm_loadu_si128(reinterpret_cast<const __m128i*>(aSrc));
px = PremultiplyVector_SSE2<aSwapRB, aOpaqueAlpha>(px);
_mm_storeu_si128(reinterpret_cast<__m128i*>(aDst), px);
aSrc += 4 * 4;
aDst += 4 * 4;
}
// This generates a table of fixed-point reciprocals representing 1/alpha // similar to the fallback implementation. However, the reciprocal must fit // in 16 bits to multiply cheaply. Observe that reciprocals of smaller alphas // require more bits than for larger alphas. We take advantage of this by // shifting the reciprocal down by either 3 or 8 bits depending on whether // the alpha value is less than 0x20. This is easy to then undo by multiplying // the color component to be unpremultiplying by either 8 or 0x100, // respectively. The 16 bit reciprocal is duplicated into both words of a // uint32_t here to reduce unpacking overhead. #define UNPREMULQ_SSE2(x) \
(0x10001U * (0xFF0220U / ((x) * ((x) < 0x20 ? 0x100 : 8)))) #define UNPREMULQ_SSE2_2(x) UNPREMULQ_SSE2(x), UNPREMULQ_SSE2((x) + 1) #define UNPREMULQ_SSE2_4(x) UNPREMULQ_SSE2_2(x), UNPREMULQ_SSE2_2((x) + 2) #define UNPREMULQ_SSE2_8(x) UNPREMULQ_SSE2_4(x), UNPREMULQ_SSE2_4((x) + 4) #define UNPREMULQ_SSE2_16(x) UNPREMULQ_SSE2_8(x), UNPREMULQ_SSE2_8((x) + 8) #define UNPREMULQ_SSE2_32(x) UNPREMULQ_SSE2_16(x), UNPREMULQ_SSE2_16((x) + 16) staticconst uint32_t sUnpremultiplyTable_SSE2[256] = {0,
UNPREMULQ_SSE2(1),
UNPREMULQ_SSE2_2(2),
UNPREMULQ_SSE2_4(4),
UNPREMULQ_SSE2_8(8),
UNPREMULQ_SSE2_16(16),
UNPREMULQ_SSE2_32(32),
UNPREMULQ_SSE2_32(64),
UNPREMULQ_SSE2_32(96),
UNPREMULQ_SSE2_32(128),
UNPREMULQ_SSE2_32(160),
UNPREMULQ_SSE2_32(192),
UNPREMULQ_SSE2_32(224)};
// Unpremultiply a vector of 4 pixels using splayed math and a reciprocal table // that avoids doing any actual division. template <bool aSwapRB> static MOZ_ALWAYS_INLINE __m128i UnpremultiplyVector_SSE2(const __m128i& aSrc) { // Isolate R and B with mask.
__m128i rb = _mm_and_si128(aSrc, _mm_set1_epi32(0x00FF00FF)); // Swap R and B if necessary. if (aSwapRB) {
rb = _mm_shufflelo_epi16(rb, _MM_SHUFFLE(2, 3, 0, 1));
rb = _mm_shufflehi_epi16(rb, _MM_SHUFFLE(2, 3, 0, 1));
}
// Isolate G and A by shifting down to bottom of word.
__m128i ga = _mm_srli_epi16(aSrc, 8); // Extract the alphas for the 4 pixels from the now isolated words. int a1 = _mm_extract_epi16(ga, 1); int a2 = _mm_extract_epi16(ga, 3); int a3 = _mm_extract_epi16(ga, 5); int a4 = _mm_extract_epi16(ga, 7);
// Load the 16 bit reciprocals from the table for each alpha. // The reciprocals are doubled in each uint32_t entry. // Unpack them to a final vector of duplicated reciprocals of // the form Q1 Q1 Q2 Q2 Q3 Q3 Q4 Q4.
__m128i q12 =
_mm_unpacklo_epi32(_mm_cvtsi32_si128(sUnpremultiplyTable_SSE2[a1]),
_mm_cvtsi32_si128(sUnpremultiplyTable_SSE2[a2]));
__m128i q34 =
_mm_unpacklo_epi32(_mm_cvtsi32_si128(sUnpremultiplyTable_SSE2[a3]),
_mm_cvtsi32_si128(sUnpremultiplyTable_SSE2[a4]));
__m128i q1234 = _mm_unpacklo_epi64(q12, q34);
// Check if the alphas are less than 0x20, so that we can undo // scaling of the reciprocals as appropriate.
__m128i scale = _mm_cmplt_epi32(ga, _mm_set1_epi32(0x00200000)); // Produce scale factors by ((a < 0x20) ^ 8) & 0x108, // such that scale is 0x100 if < 0x20, and 8 otherwise.
scale = _mm_xor_si128(scale, _mm_set1_epi16(8));
scale = _mm_and_si128(scale, _mm_set1_epi16(0x108)); // Isolate G now so that we don't accidentally unpremultiply A.
ga = _mm_and_si128(ga, _mm_set1_epi32(0x000000FF));
// Scale R, B, and G as required depending on reciprocal precision.
rb = _mm_mullo_epi16(rb, scale);
ga = _mm_mullo_epi16(ga, scale);
// Multiply R, B, and G by the reciprocal, only taking the high word // too effectively shift right by 16.
rb = _mm_mulhi_epu16(rb, q1234);
ga = _mm_mulhi_epu16(ga, q1234);
// Combine back to final pixel with rb | (ga << 8) | (aSrc & 0xFF000000), // which will add back on the original alpha value unchanged.
ga = _mm_slli_si128(ga, 1);
ga = _mm_or_si128(ga, _mm_and_si128(aSrc, _mm_set1_epi32(0xFF000000))); return _mm_or_si128(rb, ga);
}
template <bool aSwapRB> static MOZ_ALWAYS_INLINE void UnpremultiplyChunk_SSE2(const uint8_t*& aSrc,
uint8_t*& aDst,
int32_t aAlignedRow,
int32_t aRemainder) { // Process all 4-pixel chunks as one vector. for (const uint8_t* end = aSrc + aAlignedRow; aSrc < end;) {
__m128i px = _mm_loadu_si128(reinterpret_cast<const __m128i*>(aSrc));
px = UnpremultiplyVector_SSE2<aSwapRB>(px);
_mm_storeu_si128(reinterpret_cast<__m128i*>(aDst), px);
aSrc += 4 * 4;
aDst += 4 * 4;
}
// Swizzle a vector of 4 pixels providing swaps and opaquifying. template <bool aSwapRB, bool aOpaqueAlpha> static MOZ_ALWAYS_INLINE __m128i SwizzleVector_SSE2(const __m128i& aSrc) { // Isolate R and B.
__m128i rb = _mm_and_si128(aSrc, _mm_set1_epi32(0x00FF00FF)); // Swap R and B.
rb = _mm_shufflelo_epi16(rb, _MM_SHUFFLE(2, 3, 0, 1));
rb = _mm_shufflehi_epi16(rb, _MM_SHUFFLE(2, 3, 0, 1)); // Isolate G and A.
__m128i ga = _mm_and_si128(aSrc, _mm_set1_epi32(0xFF00FF00)); // Force alpha to 255 if necessary. if (aOpaqueAlpha) {
ga = _mm_or_si128(ga, _mm_set1_epi32(0xFF000000));
} // Combine everything back together. return _mm_or_si128(rb, ga);
}
#if 0 // These specializations currently do not profile faster than the generic versions, // so disable them for now.
// Optimized implementations for when there is no R and B swap. template<>
MOZ_ALWAYS_INLINE __m128i
SwizzleVector_SSE2<false, true>(const __m128i& aSrc)
{ // Force alpha to 255. return _mm_or_si128(aSrc, _mm_set1_epi32(0xFF000000));
}
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