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1 // Copyright 2015 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Utilities for processing transparent channel, SSE4.1 variant.
11 //
12 // Author: Skal (pascal.massimino@gmail.com)
13 
14 #include "src/dsp/dsp.h"
15 
16 #if defined(WEBP_USE_SSE41)
17 
18 #include <smmintrin.h>
19 
20 //------------------------------------------------------------------------------
21 
ExtractAlpha_SSE41(const uint8_t * argb,int argb_stride,int width,int height,uint8_t * alpha,int alpha_stride)22 static int ExtractAlpha_SSE41(const uint8_t* argb, int argb_stride,
23                               int width, int height,
24                               uint8_t* alpha, int alpha_stride) {
25   // alpha_and stores an 'and' operation of all the alpha[] values. The final
26   // value is not 0xff if any of the alpha[] is not equal to 0xff.
27   uint32_t alpha_and = 0xff;
28   int i, j;
29   const __m128i all_0xff = _mm_set1_epi32(~0u);
30   __m128i all_alphas = all_0xff;
31 
32   // We must be able to access 3 extra bytes after the last written byte
33   // 'src[4 * width - 4]', because we don't know if alpha is the first or the
34   // last byte of the quadruplet.
35   const int limit = (width - 1) & ~15;
36   const __m128i kCstAlpha0 = _mm_set_epi8(-1, -1, -1, -1, -1, -1, -1, -1,
37                                           -1, -1, -1, -1, 12, 8, 4, 0);
38   const __m128i kCstAlpha1 = _mm_set_epi8(-1, -1, -1, -1, -1, -1, -1, -1,
39                                           12, 8, 4, 0, -1, -1, -1, -1);
40   const __m128i kCstAlpha2 = _mm_set_epi8(-1, -1, -1, -1, 12, 8, 4, 0,
41                                           -1, -1, -1, -1, -1, -1, -1, -1);
42   const __m128i kCstAlpha3 = _mm_set_epi8(12, 8, 4, 0, -1, -1, -1, -1,
43                                           -1, -1, -1, -1, -1, -1, -1, -1);
44   for (j = 0; j < height; ++j) {
45     const __m128i* src = (const __m128i*)argb;
46     for (i = 0; i < limit; i += 16) {
47       // load 64 argb bytes
48       const __m128i a0 = _mm_loadu_si128(src + 0);
49       const __m128i a1 = _mm_loadu_si128(src + 1);
50       const __m128i a2 = _mm_loadu_si128(src + 2);
51       const __m128i a3 = _mm_loadu_si128(src + 3);
52       const __m128i b0 = _mm_shuffle_epi8(a0, kCstAlpha0);
53       const __m128i b1 = _mm_shuffle_epi8(a1, kCstAlpha1);
54       const __m128i b2 = _mm_shuffle_epi8(a2, kCstAlpha2);
55       const __m128i b3 = _mm_shuffle_epi8(a3, kCstAlpha3);
56       const __m128i c0 = _mm_or_si128(b0, b1);
57       const __m128i c1 = _mm_or_si128(b2, b3);
58       const __m128i d0 = _mm_or_si128(c0, c1);
59       // store
60       _mm_storeu_si128((__m128i*)&alpha[i], d0);
61       // accumulate sixteen alpha 'and' in parallel
62       all_alphas = _mm_and_si128(all_alphas, d0);
63       src += 4;
64     }
65     for (; i < width; ++i) {
66       const uint32_t alpha_value = argb[4 * i];
67       alpha[i] = alpha_value;
68       alpha_and &= alpha_value;
69     }
70     argb += argb_stride;
71     alpha += alpha_stride;
72   }
73   // Combine the sixteen alpha 'and' into an 8-bit mask.
74   alpha_and |= 0xff00u;  // pretend the upper bits [8..15] were tested ok.
75   alpha_and &= _mm_movemask_epi8(_mm_cmpeq_epi8(all_alphas, all_0xff));
76   return (alpha_and == 0xffffu);
77 }
78 
79 //------------------------------------------------------------------------------
80 // Entry point
81 
82 extern void WebPInitAlphaProcessingSSE41(void);
83 
WebPInitAlphaProcessingSSE41(void)84 WEBP_TSAN_IGNORE_FUNCTION void WebPInitAlphaProcessingSSE41(void) {
85   WebPExtractAlpha = ExtractAlpha_SSE41;
86 }
87 
88 #else  // !WEBP_USE_SSE41
89 
90 WEBP_DSP_INIT_STUB(WebPInitAlphaProcessingSSE41)
91 
92 #endif  // WEBP_USE_SSE41
93