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1 // Copyright 2014 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.
11 //
12 // Author: Skal (pascal.massimino@gmail.com)
13 
14 #include "src/dsp/dsp.h"
15 
16 #if defined(WEBP_USE_SSE2)
17 #include <emmintrin.h>
18 
19 //------------------------------------------------------------------------------
20 
DispatchAlpha_SSE2(const uint8_t * alpha,int alpha_stride,int width,int height,uint8_t * dst,int dst_stride)21 static int DispatchAlpha_SSE2(const uint8_t* alpha, int alpha_stride,
22                               int width, int height,
23                               uint8_t* dst, int dst_stride) {
24   // alpha_and stores an 'and' operation of all the alpha[] values. The final
25   // value is not 0xff if any of the alpha[] is not equal to 0xff.
26   uint32_t alpha_and = 0xff;
27   int i, j;
28   const __m128i zero = _mm_setzero_si128();
29   const __m128i rgb_mask = _mm_set1_epi32(0xffffff00u);  // to preserve RGB
30   const __m128i all_0xff = _mm_set_epi32(0, 0, ~0u, ~0u);
31   __m128i all_alphas = all_0xff;
32 
33   // We must be able to access 3 extra bytes after the last written byte
34   // 'dst[4 * width - 4]', because we don't know if alpha is the first or the
35   // last byte of the quadruplet.
36   const int limit = (width - 1) & ~7;
37 
38   for (j = 0; j < height; ++j) {
39     __m128i* out = (__m128i*)dst;
40     for (i = 0; i < limit; i += 8) {
41       // load 8 alpha bytes
42       const __m128i a0 = _mm_loadl_epi64((const __m128i*)&alpha[i]);
43       const __m128i a1 = _mm_unpacklo_epi8(a0, zero);
44       const __m128i a2_lo = _mm_unpacklo_epi16(a1, zero);
45       const __m128i a2_hi = _mm_unpackhi_epi16(a1, zero);
46       // load 8 dst pixels (32 bytes)
47       const __m128i b0_lo = _mm_loadu_si128(out + 0);
48       const __m128i b0_hi = _mm_loadu_si128(out + 1);
49       // mask dst alpha values
50       const __m128i b1_lo = _mm_and_si128(b0_lo, rgb_mask);
51       const __m128i b1_hi = _mm_and_si128(b0_hi, rgb_mask);
52       // combine
53       const __m128i b2_lo = _mm_or_si128(b1_lo, a2_lo);
54       const __m128i b2_hi = _mm_or_si128(b1_hi, a2_hi);
55       // store
56       _mm_storeu_si128(out + 0, b2_lo);
57       _mm_storeu_si128(out + 1, b2_hi);
58       // accumulate eight alpha 'and' in parallel
59       all_alphas = _mm_and_si128(all_alphas, a0);
60       out += 2;
61     }
62     for (; i < width; ++i) {
63       const uint32_t alpha_value = alpha[i];
64       dst[4 * i] = alpha_value;
65       alpha_and &= alpha_value;
66     }
67     alpha += alpha_stride;
68     dst += dst_stride;
69   }
70   // Combine the eight alpha 'and' into a 8-bit mask.
71   alpha_and &= _mm_movemask_epi8(_mm_cmpeq_epi8(all_alphas, all_0xff));
72   return (alpha_and != 0xff);
73 }
74 
DispatchAlphaToGreen_SSE2(const uint8_t * alpha,int alpha_stride,int width,int height,uint32_t * dst,int dst_stride)75 static void DispatchAlphaToGreen_SSE2(const uint8_t* alpha, int alpha_stride,
76                                       int width, int height,
77                                       uint32_t* dst, int dst_stride) {
78   int i, j;
79   const __m128i zero = _mm_setzero_si128();
80   const int limit = width & ~15;
81   for (j = 0; j < height; ++j) {
82     for (i = 0; i < limit; i += 16) {   // process 16 alpha bytes
83       const __m128i a0 = _mm_loadu_si128((const __m128i*)&alpha[i]);
84       const __m128i a1 = _mm_unpacklo_epi8(zero, a0);  // note the 'zero' first!
85       const __m128i b1 = _mm_unpackhi_epi8(zero, a0);
86       const __m128i a2_lo = _mm_unpacklo_epi16(a1, zero);
87       const __m128i b2_lo = _mm_unpacklo_epi16(b1, zero);
88       const __m128i a2_hi = _mm_unpackhi_epi16(a1, zero);
89       const __m128i b2_hi = _mm_unpackhi_epi16(b1, zero);
90       _mm_storeu_si128((__m128i*)&dst[i +  0], a2_lo);
91       _mm_storeu_si128((__m128i*)&dst[i +  4], a2_hi);
92       _mm_storeu_si128((__m128i*)&dst[i +  8], b2_lo);
93       _mm_storeu_si128((__m128i*)&dst[i + 12], b2_hi);
94     }
95     for (; i < width; ++i) dst[i] = alpha[i] << 8;
96     alpha += alpha_stride;
97     dst += dst_stride;
98   }
99 }
100 
ExtractAlpha_SSE2(const uint8_t * argb,int argb_stride,int width,int height,uint8_t * alpha,int alpha_stride)101 static int ExtractAlpha_SSE2(const uint8_t* argb, int argb_stride,
102                              int width, int height,
103                              uint8_t* alpha, int alpha_stride) {
104   // alpha_and stores an 'and' operation of all the alpha[] values. The final
105   // value is not 0xff if any of the alpha[] is not equal to 0xff.
106   uint32_t alpha_and = 0xff;
107   int i, j;
108   const __m128i a_mask = _mm_set1_epi32(0xffu);  // to preserve alpha
109   const __m128i all_0xff = _mm_set_epi32(0, 0, ~0u, ~0u);
110   __m128i all_alphas = all_0xff;
111 
112   // We must be able to access 3 extra bytes after the last written byte
113   // 'src[4 * width - 4]', because we don't know if alpha is the first or the
114   // last byte of the quadruplet.
115   const int limit = (width - 1) & ~7;
116 
117   for (j = 0; j < height; ++j) {
118     const __m128i* src = (const __m128i*)argb;
119     for (i = 0; i < limit; i += 8) {
120       // load 32 argb bytes
121       const __m128i a0 = _mm_loadu_si128(src + 0);
122       const __m128i a1 = _mm_loadu_si128(src + 1);
123       const __m128i b0 = _mm_and_si128(a0, a_mask);
124       const __m128i b1 = _mm_and_si128(a1, a_mask);
125       const __m128i c0 = _mm_packs_epi32(b0, b1);
126       const __m128i d0 = _mm_packus_epi16(c0, c0);
127       // store
128       _mm_storel_epi64((__m128i*)&alpha[i], d0);
129       // accumulate eight alpha 'and' in parallel
130       all_alphas = _mm_and_si128(all_alphas, d0);
131       src += 2;
132     }
133     for (; i < width; ++i) {
134       const uint32_t alpha_value = argb[4 * i];
135       alpha[i] = alpha_value;
136       alpha_and &= alpha_value;
137     }
138     argb += argb_stride;
139     alpha += alpha_stride;
140   }
141   // Combine the eight alpha 'and' into a 8-bit mask.
142   alpha_and &= _mm_movemask_epi8(_mm_cmpeq_epi8(all_alphas, all_0xff));
143   return (alpha_and == 0xff);
144 }
145 
146 //------------------------------------------------------------------------------
147 // Non-dither premultiplied modes
148 
149 #define MULTIPLIER(a)   ((a) * 0x8081)
150 #define PREMULTIPLY(x, m) (((x) * (m)) >> 23)
151 
152 // We can't use a 'const int' for the SHUFFLE value, because it has to be an
153 // immediate in the _mm_shufflexx_epi16() instruction. We really need a macro.
154 // We use: v / 255 = (v * 0x8081) >> 23, where v = alpha * {r,g,b} is a 16bit
155 // value.
156 #define APPLY_ALPHA(RGBX, SHUFFLE) do {                              \
157   const __m128i argb0 = _mm_loadu_si128((const __m128i*)&(RGBX));    \
158   const __m128i argb1_lo = _mm_unpacklo_epi8(argb0, zero);           \
159   const __m128i argb1_hi = _mm_unpackhi_epi8(argb0, zero);           \
160   const __m128i alpha0_lo = _mm_or_si128(argb1_lo, kMask);           \
161   const __m128i alpha0_hi = _mm_or_si128(argb1_hi, kMask);           \
162   const __m128i alpha1_lo = _mm_shufflelo_epi16(alpha0_lo, SHUFFLE); \
163   const __m128i alpha1_hi = _mm_shufflelo_epi16(alpha0_hi, SHUFFLE); \
164   const __m128i alpha2_lo = _mm_shufflehi_epi16(alpha1_lo, SHUFFLE); \
165   const __m128i alpha2_hi = _mm_shufflehi_epi16(alpha1_hi, SHUFFLE); \
166   /* alpha2 = [ff a0 a0 a0][ff a1 a1 a1] */                          \
167   const __m128i A0_lo = _mm_mullo_epi16(alpha2_lo, argb1_lo);        \
168   const __m128i A0_hi = _mm_mullo_epi16(alpha2_hi, argb1_hi);        \
169   const __m128i A1_lo = _mm_mulhi_epu16(A0_lo, kMult);               \
170   const __m128i A1_hi = _mm_mulhi_epu16(A0_hi, kMult);               \
171   const __m128i A2_lo = _mm_srli_epi16(A1_lo, 7);                    \
172   const __m128i A2_hi = _mm_srli_epi16(A1_hi, 7);                    \
173   const __m128i A3 = _mm_packus_epi16(A2_lo, A2_hi);                 \
174   _mm_storeu_si128((__m128i*)&(RGBX), A3);                           \
175 } while (0)
176 
ApplyAlphaMultiply_SSE2(uint8_t * rgba,int alpha_first,int w,int h,int stride)177 static void ApplyAlphaMultiply_SSE2(uint8_t* rgba, int alpha_first,
178                                     int w, int h, int stride) {
179   const __m128i zero = _mm_setzero_si128();
180   const __m128i kMult = _mm_set1_epi16(0x8081u);
181   const __m128i kMask = _mm_set_epi16(0, 0xff, 0xff, 0, 0, 0xff, 0xff, 0);
182   const int kSpan = 4;
183   while (h-- > 0) {
184     uint32_t* const rgbx = (uint32_t*)rgba;
185     int i;
186     if (!alpha_first) {
187       for (i = 0; i + kSpan <= w; i += kSpan) {
188         APPLY_ALPHA(rgbx[i], _MM_SHUFFLE(2, 3, 3, 3));
189       }
190     } else {
191       for (i = 0; i + kSpan <= w; i += kSpan) {
192         APPLY_ALPHA(rgbx[i], _MM_SHUFFLE(0, 0, 0, 1));
193       }
194     }
195     // Finish with left-overs.
196     for (; i < w; ++i) {
197       uint8_t* const rgb = rgba + (alpha_first ? 1 : 0);
198       const uint8_t* const alpha = rgba + (alpha_first ? 0 : 3);
199       const uint32_t a = alpha[4 * i];
200       if (a != 0xff) {
201         const uint32_t mult = MULTIPLIER(a);
202         rgb[4 * i + 0] = PREMULTIPLY(rgb[4 * i + 0], mult);
203         rgb[4 * i + 1] = PREMULTIPLY(rgb[4 * i + 1], mult);
204         rgb[4 * i + 2] = PREMULTIPLY(rgb[4 * i + 2], mult);
205       }
206     }
207     rgba += stride;
208   }
209 }
210 #undef MULTIPLIER
211 #undef PREMULTIPLY
212 
213 //------------------------------------------------------------------------------
214 // Alpha detection
215 
HasAlpha8b_SSE2(const uint8_t * src,int length)216 static int HasAlpha8b_SSE2(const uint8_t* src, int length) {
217   const __m128i all_0xff = _mm_set1_epi8((char)0xff);
218   int i = 0;
219   for (; i + 16 <= length; i += 16) {
220     const __m128i v = _mm_loadu_si128((const __m128i*)(src + i));
221     const __m128i bits = _mm_cmpeq_epi8(v, all_0xff);
222     const int mask = _mm_movemask_epi8(bits);
223     if (mask != 0xffff) return 1;
224   }
225   for (; i < length; ++i) if (src[i] != 0xff) return 1;
226   return 0;
227 }
228 
HasAlpha32b_SSE2(const uint8_t * src,int length)229 static int HasAlpha32b_SSE2(const uint8_t* src, int length) {
230   const __m128i alpha_mask = _mm_set1_epi32(0xff);
231   const __m128i all_0xff = _mm_set1_epi8((char)0xff);
232   int i = 0;
233   // We don't know if we can access the last 3 bytes after the last alpha
234   // value 'src[4 * length - 4]' (because we don't know if alpha is the first
235   // or the last byte of the quadruplet). Hence the '-3' protection below.
236   length = length * 4 - 3;   // size in bytes
237   for (; i + 64 <= length; i += 64) {
238     const __m128i a0 = _mm_loadu_si128((const __m128i*)(src + i +  0));
239     const __m128i a1 = _mm_loadu_si128((const __m128i*)(src + i + 16));
240     const __m128i a2 = _mm_loadu_si128((const __m128i*)(src + i + 32));
241     const __m128i a3 = _mm_loadu_si128((const __m128i*)(src + i + 48));
242     const __m128i b0 = _mm_and_si128(a0, alpha_mask);
243     const __m128i b1 = _mm_and_si128(a1, alpha_mask);
244     const __m128i b2 = _mm_and_si128(a2, alpha_mask);
245     const __m128i b3 = _mm_and_si128(a3, alpha_mask);
246     const __m128i c0 = _mm_packs_epi32(b0, b1);
247     const __m128i c1 = _mm_packs_epi32(b2, b3);
248     const __m128i d  = _mm_packus_epi16(c0, c1);
249     const __m128i bits = _mm_cmpeq_epi8(d, all_0xff);
250     const int mask = _mm_movemask_epi8(bits);
251     if (mask != 0xffff) return 1;
252   }
253   for (; i + 32 <= length; i += 32) {
254     const __m128i a0 = _mm_loadu_si128((const __m128i*)(src + i +  0));
255     const __m128i a1 = _mm_loadu_si128((const __m128i*)(src + i + 16));
256     const __m128i b0 = _mm_and_si128(a0, alpha_mask);
257     const __m128i b1 = _mm_and_si128(a1, alpha_mask);
258     const __m128i c  = _mm_packs_epi32(b0, b1);
259     const __m128i d  = _mm_packus_epi16(c, c);
260     const __m128i bits = _mm_cmpeq_epi8(d, all_0xff);
261     const int mask = _mm_movemask_epi8(bits);
262     if (mask != 0xffff) return 1;
263   }
264   for (; i <= length; i += 4) if (src[i] != 0xff) return 1;
265   return 0;
266 }
267 
268 // -----------------------------------------------------------------------------
269 // Apply alpha value to rows
270 
MultARGBRow_SSE2(uint32_t * const ptr,int width,int inverse)271 static void MultARGBRow_SSE2(uint32_t* const ptr, int width, int inverse) {
272   int x = 0;
273   if (!inverse) {
274     const int kSpan = 2;
275     const __m128i zero = _mm_setzero_si128();
276     const __m128i k128 = _mm_set1_epi16(128);
277     const __m128i kMult = _mm_set1_epi16(0x0101);
278     const __m128i kMask = _mm_set_epi16(0, 0xff, 0, 0, 0, 0xff, 0, 0);
279     for (x = 0; x + kSpan <= width; x += kSpan) {
280       // To compute 'result = (int)(a * x / 255. + .5)', we use:
281       //   tmp = a * v + 128, result = (tmp * 0x0101u) >> 16
282       const __m128i A0 = _mm_loadl_epi64((const __m128i*)&ptr[x]);
283       const __m128i A1 = _mm_unpacklo_epi8(A0, zero);
284       const __m128i A2 = _mm_or_si128(A1, kMask);
285       const __m128i A3 = _mm_shufflelo_epi16(A2, _MM_SHUFFLE(2, 3, 3, 3));
286       const __m128i A4 = _mm_shufflehi_epi16(A3, _MM_SHUFFLE(2, 3, 3, 3));
287       // here, A4 = [ff a0 a0 a0][ff a1 a1 a1]
288       const __m128i A5 = _mm_mullo_epi16(A4, A1);
289       const __m128i A6 = _mm_add_epi16(A5, k128);
290       const __m128i A7 = _mm_mulhi_epu16(A6, kMult);
291       const __m128i A10 = _mm_packus_epi16(A7, zero);
292       _mm_storel_epi64((__m128i*)&ptr[x], A10);
293     }
294   }
295   width -= x;
296   if (width > 0) WebPMultARGBRow_C(ptr + x, width, inverse);
297 }
298 
MultRow_SSE2(uint8_t * const ptr,const uint8_t * const alpha,int width,int inverse)299 static void MultRow_SSE2(uint8_t* const ptr, const uint8_t* const alpha,
300                          int width, int inverse) {
301   int x = 0;
302   if (!inverse) {
303     const __m128i zero = _mm_setzero_si128();
304     const __m128i k128 = _mm_set1_epi16(128);
305     const __m128i kMult = _mm_set1_epi16(0x0101);
306     for (x = 0; x + 8 <= width; x += 8) {
307       const __m128i v0 = _mm_loadl_epi64((__m128i*)&ptr[x]);
308       const __m128i a0 = _mm_loadl_epi64((const __m128i*)&alpha[x]);
309       const __m128i v1 = _mm_unpacklo_epi8(v0, zero);
310       const __m128i a1 = _mm_unpacklo_epi8(a0, zero);
311       const __m128i v2 = _mm_mullo_epi16(v1, a1);
312       const __m128i v3 = _mm_add_epi16(v2, k128);
313       const __m128i v4 = _mm_mulhi_epu16(v3, kMult);
314       const __m128i v5 = _mm_packus_epi16(v4, zero);
315       _mm_storel_epi64((__m128i*)&ptr[x], v5);
316     }
317   }
318   width -= x;
319   if (width > 0) WebPMultRow_C(ptr + x, alpha + x, width, inverse);
320 }
321 
322 //------------------------------------------------------------------------------
323 // Entry point
324 
325 extern void WebPInitAlphaProcessingSSE2(void);
326 
WebPInitAlphaProcessingSSE2(void)327 WEBP_TSAN_IGNORE_FUNCTION void WebPInitAlphaProcessingSSE2(void) {
328   WebPMultARGBRow = MultARGBRow_SSE2;
329   WebPMultRow = MultRow_SSE2;
330   WebPApplyAlphaMultiply = ApplyAlphaMultiply_SSE2;
331   WebPDispatchAlpha = DispatchAlpha_SSE2;
332   WebPDispatchAlphaToGreen = DispatchAlphaToGreen_SSE2;
333   WebPExtractAlpha = ExtractAlpha_SSE2;
334 
335   WebPHasAlpha8b = HasAlpha8b_SSE2;
336   WebPHasAlpha32b = HasAlpha32b_SSE2;
337 }
338 
339 #else  // !WEBP_USE_SSE2
340 
341 WEBP_DSP_INIT_STUB(WebPInitAlphaProcessingSSE2)
342 
343 #endif  // WEBP_USE_SSE2
344