1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677 |
- // Copyright 2014 Google Inc. All Rights Reserved.
- //
- // Use of this source code is governed by a BSD-style license
- // that can be found in the COPYING file in the root of the source
- // tree. An additional intellectual property rights grant can be found
- // in the file PATENTS. All contributing project authors may
- // be found in the AUTHORS file in the root of the source tree.
- // -----------------------------------------------------------------------------
- //
- // Utilities for processing transparent channel.
- //
- // Author: Skal (pascal.massimino@gmail.com)
- #include "./dsp.h"
- #if defined(WEBP_USE_SSE2)
- #include <emmintrin.h>
- //------------------------------------------------------------------------------
- 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);
- }
- #endif // WEBP_USE_SSE2
- //------------------------------------------------------------------------------
- // Init function
- extern void WebPInitAlphaProcessingSSE2(void);
- void WebPInitAlphaProcessingSSE2(void) {
- #if defined(WEBP_USE_SSE2)
- WebPExtractAlpha = ExtractAlpha;
- #endif
- }
|