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lossless_enc_sse2.c (32857B)


      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 // SSE2 variant of methods for lossless encoder
     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 #include <assert.h>
     20 #include <string.h>
     21 
     22 #include "src/dsp/cpu.h"
     23 #include "src/dsp/lossless.h"
     24 #include "src/dsp/lossless_common.h"
     25 #include "src/utils/utils.h"
     26 #include "src/webp/format_constants.h"
     27 #include "src/webp/types.h"
     28 
     29 // For sign-extended multiplying constants, pre-shifted by 5:
     30 #define CST_5b(X)  (((int16_t)((uint16_t)(X) << 8)) >> 5)
     31 
     32 //------------------------------------------------------------------------------
     33 // Subtract-Green Transform
     34 
     35 static void SubtractGreenFromBlueAndRed_SSE2(uint32_t* argb_data,
     36                                             int num_pixels) {
     37  int i;
     38  for (i = 0; i + 4 <= num_pixels; i += 4) {
     39    const __m128i in = _mm_loadu_si128((__m128i*)&argb_data[i]); // argb
     40    const __m128i A = _mm_srli_epi16(in, 8);     // 0 a 0 g
     41    const __m128i B = _mm_shufflelo_epi16(A, _MM_SHUFFLE(2, 2, 0, 0));
     42    const __m128i C = _mm_shufflehi_epi16(B, _MM_SHUFFLE(2, 2, 0, 0));  // 0g0g
     43    const __m128i out = _mm_sub_epi8(in, C);
     44    _mm_storeu_si128((__m128i*)&argb_data[i], out);
     45  }
     46  // fallthrough and finish off with plain-C
     47  if (i != num_pixels) {
     48    VP8LSubtractGreenFromBlueAndRed_C(argb_data + i, num_pixels - i);
     49  }
     50 }
     51 
     52 //------------------------------------------------------------------------------
     53 // Color Transform
     54 
     55 #define MK_CST_16(HI, LO) \
     56  _mm_set1_epi32((int)(((uint32_t)(HI) << 16) | ((LO) & 0xffff)))
     57 
     58 static void TransformColor_SSE2(const VP8LMultipliers* WEBP_RESTRICT const m,
     59                                uint32_t* WEBP_RESTRICT argb_data,
     60                                int num_pixels) {
     61  const __m128i mults_rb = MK_CST_16(CST_5b(m->green_to_red),
     62                                     CST_5b(m->green_to_blue));
     63  const __m128i mults_b2 = MK_CST_16(CST_5b(m->red_to_blue), 0);
     64  const __m128i mask_ag = _mm_set1_epi32((int)0xff00ff00);  // alpha-green masks
     65  const __m128i mask_rb = _mm_set1_epi32(0x00ff00ff);       // red-blue masks
     66  int i;
     67  for (i = 0; i + 4 <= num_pixels; i += 4) {
     68    const __m128i in = _mm_loadu_si128((__m128i*)&argb_data[i]); // argb
     69    const __m128i A = _mm_and_si128(in, mask_ag);     // a   0   g   0
     70    const __m128i B = _mm_shufflelo_epi16(A, _MM_SHUFFLE(2, 2, 0, 0));
     71    const __m128i C = _mm_shufflehi_epi16(B, _MM_SHUFFLE(2, 2, 0, 0));  // g0g0
     72    const __m128i D = _mm_mulhi_epi16(C, mults_rb);    // x dr  x db1
     73    const __m128i E = _mm_slli_epi16(in, 8);           // r 0   b   0
     74    const __m128i F = _mm_mulhi_epi16(E, mults_b2);    // x db2 0   0
     75    const __m128i G = _mm_srli_epi32(F, 16);           // 0 0   x db2
     76    const __m128i H = _mm_add_epi8(G, D);              // x dr  x  db
     77    const __m128i I = _mm_and_si128(H, mask_rb);       // 0 dr  0  db
     78    const __m128i out = _mm_sub_epi8(in, I);
     79    _mm_storeu_si128((__m128i*)&argb_data[i], out);
     80  }
     81  // fallthrough and finish off with plain-C
     82  if (i != num_pixels) {
     83    VP8LTransformColor_C(m, argb_data + i, num_pixels - i);
     84  }
     85 }
     86 
     87 //------------------------------------------------------------------------------
     88 #define SPAN 8
     89 static void CollectColorBlueTransforms_SSE2(const uint32_t* WEBP_RESTRICT argb,
     90                                            int stride,
     91                                            int tile_width, int tile_height,
     92                                            int green_to_blue, int red_to_blue,
     93                                            uint32_t histo[]) {
     94  const __m128i mults_r = MK_CST_16(CST_5b(red_to_blue), 0);
     95  const __m128i mults_g = MK_CST_16(0, CST_5b(green_to_blue));
     96  const __m128i mask_g = _mm_set1_epi32(0x00ff00);  // green mask
     97  const __m128i mask_b = _mm_set1_epi32(0x0000ff);  // blue mask
     98  int y;
     99  for (y = 0; y < tile_height; ++y) {
    100    const uint32_t* const src = argb + y * stride;
    101    int i, x;
    102    for (x = 0; x + SPAN <= tile_width; x += SPAN) {
    103      uint16_t values[SPAN];
    104      const __m128i in0 = _mm_loadu_si128((__m128i*)&src[x +        0]);
    105      const __m128i in1 = _mm_loadu_si128((__m128i*)&src[x + SPAN / 2]);
    106      const __m128i A0 = _mm_slli_epi16(in0, 8);        // r 0  | b 0
    107      const __m128i A1 = _mm_slli_epi16(in1, 8);
    108      const __m128i B0 = _mm_and_si128(in0, mask_g);    // 0 0  | g 0
    109      const __m128i B1 = _mm_and_si128(in1, mask_g);
    110      const __m128i C0 = _mm_mulhi_epi16(A0, mults_r);  // x db | 0 0
    111      const __m128i C1 = _mm_mulhi_epi16(A1, mults_r);
    112      const __m128i D0 = _mm_mulhi_epi16(B0, mults_g);  // 0 0  | x db
    113      const __m128i D1 = _mm_mulhi_epi16(B1, mults_g);
    114      const __m128i E0 = _mm_sub_epi8(in0, D0);         // x x  | x b'
    115      const __m128i E1 = _mm_sub_epi8(in1, D1);
    116      const __m128i F0 = _mm_srli_epi32(C0, 16);        // 0 0  | x db
    117      const __m128i F1 = _mm_srli_epi32(C1, 16);
    118      const __m128i G0 = _mm_sub_epi8(E0, F0);          // 0 0  | x b'
    119      const __m128i G1 = _mm_sub_epi8(E1, F1);
    120      const __m128i H0 = _mm_and_si128(G0, mask_b);     // 0 0  | 0 b
    121      const __m128i H1 = _mm_and_si128(G1, mask_b);
    122      const __m128i I = _mm_packs_epi32(H0, H1);        // 0 b' | 0 b'
    123      _mm_storeu_si128((__m128i*)values, I);
    124      for (i = 0; i < SPAN; ++i) ++histo[values[i]];
    125    }
    126  }
    127  {
    128    const int left_over = tile_width & (SPAN - 1);
    129    if (left_over > 0) {
    130      VP8LCollectColorBlueTransforms_C(argb + tile_width - left_over, stride,
    131                                       left_over, tile_height,
    132                                       green_to_blue, red_to_blue, histo);
    133    }
    134  }
    135 }
    136 
    137 static void CollectColorRedTransforms_SSE2(const uint32_t* WEBP_RESTRICT argb,
    138                                           int stride,
    139                                           int tile_width, int tile_height,
    140                                           int green_to_red, uint32_t histo[]) {
    141  const __m128i mults_g = MK_CST_16(0, CST_5b(green_to_red));
    142  const __m128i mask_g = _mm_set1_epi32(0x00ff00);  // green mask
    143  const __m128i mask = _mm_set1_epi32(0xff);
    144 
    145  int y;
    146  for (y = 0; y < tile_height; ++y) {
    147    const uint32_t* const src = argb + y * stride;
    148    int i, x;
    149    for (x = 0; x + SPAN <= tile_width; x += SPAN) {
    150      uint16_t values[SPAN];
    151      const __m128i in0 = _mm_loadu_si128((__m128i*)&src[x +        0]);
    152      const __m128i in1 = _mm_loadu_si128((__m128i*)&src[x + SPAN / 2]);
    153      const __m128i A0 = _mm_and_si128(in0, mask_g);    // 0 0  | g 0
    154      const __m128i A1 = _mm_and_si128(in1, mask_g);
    155      const __m128i B0 = _mm_srli_epi32(in0, 16);       // 0 0  | x r
    156      const __m128i B1 = _mm_srli_epi32(in1, 16);
    157      const __m128i C0 = _mm_mulhi_epi16(A0, mults_g);  // 0 0  | x dr
    158      const __m128i C1 = _mm_mulhi_epi16(A1, mults_g);
    159      const __m128i E0 = _mm_sub_epi8(B0, C0);          // x x  | x r'
    160      const __m128i E1 = _mm_sub_epi8(B1, C1);
    161      const __m128i F0 = _mm_and_si128(E0, mask);       // 0 0  | 0 r'
    162      const __m128i F1 = _mm_and_si128(E1, mask);
    163      const __m128i I = _mm_packs_epi32(F0, F1);
    164      _mm_storeu_si128((__m128i*)values, I);
    165      for (i = 0; i < SPAN; ++i) ++histo[values[i]];
    166    }
    167  }
    168  {
    169    const int left_over = tile_width & (SPAN - 1);
    170    if (left_over > 0) {
    171      VP8LCollectColorRedTransforms_C(argb + tile_width - left_over, stride,
    172                                      left_over, tile_height,
    173                                      green_to_red, histo);
    174    }
    175  }
    176 }
    177 #undef SPAN
    178 #undef MK_CST_16
    179 
    180 //------------------------------------------------------------------------------
    181 
    182 // Note we are adding uint32_t's as *signed* int32's (using _mm_add_epi32). But
    183 // that's ok since the histogram values are less than 1<<28 (max picture size).
    184 static void AddVector_SSE2(const uint32_t* WEBP_RESTRICT a,
    185                           const uint32_t* WEBP_RESTRICT b,
    186                           uint32_t* WEBP_RESTRICT out, int size) {
    187  int i = 0;
    188  int aligned_size = size & ~15;
    189  // Size is, at minimum, NUM_DISTANCE_CODES (40) and may be as large as
    190  // NUM_LITERAL_CODES (256) + NUM_LENGTH_CODES (24) + (0 or a non-zero power of
    191  // 2). See the usage in VP8LHistogramAdd().
    192  assert(size >= 16);
    193  assert(size % 2 == 0);
    194 
    195  do {
    196    const __m128i a0 = _mm_loadu_si128((const __m128i*)&a[i +  0]);
    197    const __m128i a1 = _mm_loadu_si128((const __m128i*)&a[i +  4]);
    198    const __m128i a2 = _mm_loadu_si128((const __m128i*)&a[i +  8]);
    199    const __m128i a3 = _mm_loadu_si128((const __m128i*)&a[i + 12]);
    200    const __m128i b0 = _mm_loadu_si128((const __m128i*)&b[i +  0]);
    201    const __m128i b1 = _mm_loadu_si128((const __m128i*)&b[i +  4]);
    202    const __m128i b2 = _mm_loadu_si128((const __m128i*)&b[i +  8]);
    203    const __m128i b3 = _mm_loadu_si128((const __m128i*)&b[i + 12]);
    204    _mm_storeu_si128((__m128i*)&out[i +  0], _mm_add_epi32(a0, b0));
    205    _mm_storeu_si128((__m128i*)&out[i +  4], _mm_add_epi32(a1, b1));
    206    _mm_storeu_si128((__m128i*)&out[i +  8], _mm_add_epi32(a2, b2));
    207    _mm_storeu_si128((__m128i*)&out[i + 12], _mm_add_epi32(a3, b3));
    208    i += 16;
    209  } while (i != aligned_size);
    210 
    211  if ((size & 8) != 0) {
    212    const __m128i a0 = _mm_loadu_si128((const __m128i*)&a[i + 0]);
    213    const __m128i a1 = _mm_loadu_si128((const __m128i*)&a[i + 4]);
    214    const __m128i b0 = _mm_loadu_si128((const __m128i*)&b[i + 0]);
    215    const __m128i b1 = _mm_loadu_si128((const __m128i*)&b[i + 4]);
    216    _mm_storeu_si128((__m128i*)&out[i + 0], _mm_add_epi32(a0, b0));
    217    _mm_storeu_si128((__m128i*)&out[i + 4], _mm_add_epi32(a1, b1));
    218    i += 8;
    219  }
    220 
    221  size &= 7;
    222  if (size == 4) {
    223    const __m128i a0 = _mm_loadu_si128((const __m128i*)&a[i]);
    224    const __m128i b0 = _mm_loadu_si128((const __m128i*)&b[i]);
    225    _mm_storeu_si128((__m128i*)&out[i], _mm_add_epi32(a0, b0));
    226  } else if (size == 2) {
    227    const __m128i a0 = _mm_loadl_epi64((const __m128i*)&a[i]);
    228    const __m128i b0 = _mm_loadl_epi64((const __m128i*)&b[i]);
    229    _mm_storel_epi64((__m128i*)&out[i], _mm_add_epi32(a0, b0));
    230  }
    231 }
    232 
    233 static void AddVectorEq_SSE2(const uint32_t* WEBP_RESTRICT a,
    234                             uint32_t* WEBP_RESTRICT out, int size) {
    235  int i = 0;
    236  int aligned_size = size & ~15;
    237  // Size is, at minimum, NUM_DISTANCE_CODES (40) and may be as large as
    238  // NUM_LITERAL_CODES (256) + NUM_LENGTH_CODES (24) + (0 or a non-zero power of
    239  // 2). See the usage in VP8LHistogramAdd().
    240  assert(size >= 16);
    241  assert(size % 2 == 0);
    242 
    243  do {
    244    const __m128i a0 = _mm_loadu_si128((const __m128i*)&a[i +  0]);
    245    const __m128i a1 = _mm_loadu_si128((const __m128i*)&a[i +  4]);
    246    const __m128i a2 = _mm_loadu_si128((const __m128i*)&a[i +  8]);
    247    const __m128i a3 = _mm_loadu_si128((const __m128i*)&a[i + 12]);
    248    const __m128i b0 = _mm_loadu_si128((const __m128i*)&out[i +  0]);
    249    const __m128i b1 = _mm_loadu_si128((const __m128i*)&out[i +  4]);
    250    const __m128i b2 = _mm_loadu_si128((const __m128i*)&out[i +  8]);
    251    const __m128i b3 = _mm_loadu_si128((const __m128i*)&out[i + 12]);
    252    _mm_storeu_si128((__m128i*)&out[i +  0], _mm_add_epi32(a0, b0));
    253    _mm_storeu_si128((__m128i*)&out[i +  4], _mm_add_epi32(a1, b1));
    254    _mm_storeu_si128((__m128i*)&out[i +  8], _mm_add_epi32(a2, b2));
    255    _mm_storeu_si128((__m128i*)&out[i + 12], _mm_add_epi32(a3, b3));
    256    i += 16;
    257  } while (i != aligned_size);
    258 
    259  if ((size & 8) != 0) {
    260    const __m128i a0 = _mm_loadu_si128((const __m128i*)&a[i + 0]);
    261    const __m128i a1 = _mm_loadu_si128((const __m128i*)&a[i + 4]);
    262    const __m128i b0 = _mm_loadu_si128((const __m128i*)&out[i + 0]);
    263    const __m128i b1 = _mm_loadu_si128((const __m128i*)&out[i + 4]);
    264    _mm_storeu_si128((__m128i*)&out[i + 0], _mm_add_epi32(a0, b0));
    265    _mm_storeu_si128((__m128i*)&out[i + 4], _mm_add_epi32(a1, b1));
    266    i += 8;
    267  }
    268 
    269  size &= 7;
    270  if (size == 4) {
    271    const __m128i a0 = _mm_loadu_si128((const __m128i*)&a[i]);
    272    const __m128i b0 = _mm_loadu_si128((const __m128i*)&out[i]);
    273    _mm_storeu_si128((__m128i*)&out[i], _mm_add_epi32(a0, b0));
    274  } else if (size == 2) {
    275    const __m128i a0 = _mm_loadl_epi64((const __m128i*)&a[i]);
    276    const __m128i b0 = _mm_loadl_epi64((const __m128i*)&out[i]);
    277    _mm_storel_epi64((__m128i*)&out[i], _mm_add_epi32(a0, b0));
    278  }
    279 }
    280 
    281 //------------------------------------------------------------------------------
    282 // Entropy
    283 
    284 #if !defined(WEBP_HAVE_SLOW_CLZ_CTZ)
    285 
    286 static uint64_t CombinedShannonEntropy_SSE2(const uint32_t X[256],
    287                                            const uint32_t Y[256]) {
    288  int i;
    289  uint64_t retval = 0;
    290  uint32_t sumX = 0, sumXY = 0;
    291  const __m128i zero = _mm_setzero_si128();
    292 
    293  for (i = 0; i < 256; i += 16) {
    294    const __m128i x0 = _mm_loadu_si128((const __m128i*)(X + i +  0));
    295    const __m128i y0 = _mm_loadu_si128((const __m128i*)(Y + i +  0));
    296    const __m128i x1 = _mm_loadu_si128((const __m128i*)(X + i +  4));
    297    const __m128i y1 = _mm_loadu_si128((const __m128i*)(Y + i +  4));
    298    const __m128i x2 = _mm_loadu_si128((const __m128i*)(X + i +  8));
    299    const __m128i y2 = _mm_loadu_si128((const __m128i*)(Y + i +  8));
    300    const __m128i x3 = _mm_loadu_si128((const __m128i*)(X + i + 12));
    301    const __m128i y3 = _mm_loadu_si128((const __m128i*)(Y + i + 12));
    302    const __m128i x4 = _mm_packs_epi16(_mm_packs_epi32(x0, x1),
    303                                       _mm_packs_epi32(x2, x3));
    304    const __m128i y4 = _mm_packs_epi16(_mm_packs_epi32(y0, y1),
    305                                       _mm_packs_epi32(y2, y3));
    306    const int32_t mx = _mm_movemask_epi8(_mm_cmpgt_epi8(x4, zero));
    307    int32_t my = _mm_movemask_epi8(_mm_cmpgt_epi8(y4, zero)) | mx;
    308    while (my) {
    309      const int32_t j = BitsCtz(my);
    310      uint32_t xy;
    311      if ((mx >> j) & 1) {
    312        const int x = X[i + j];
    313        sumXY += x;
    314        retval += VP8LFastSLog2(x);
    315      }
    316      xy = X[i + j] + Y[i + j];
    317      sumX += xy;
    318      retval += VP8LFastSLog2(xy);
    319      my &= my - 1;
    320    }
    321  }
    322  retval = VP8LFastSLog2(sumX) + VP8LFastSLog2(sumXY) - retval;
    323  return retval;
    324 }
    325 
    326 #else
    327 
    328 #define DONT_USE_COMBINED_SHANNON_ENTROPY_SSE2_FUNC   // won't be faster
    329 
    330 #endif
    331 
    332 //------------------------------------------------------------------------------
    333 
    334 static int VectorMismatch_SSE2(const uint32_t* const array1,
    335                               const uint32_t* const array2, int length) {
    336  int match_len;
    337 
    338  if (length >= 12) {
    339    __m128i A0 = _mm_loadu_si128((const __m128i*)&array1[0]);
    340    __m128i A1 = _mm_loadu_si128((const __m128i*)&array2[0]);
    341    match_len = 0;
    342    do {
    343      // Loop unrolling and early load both provide a speedup of 10% for the
    344      // current function. Also, max_limit can be MAX_LENGTH=4096 at most.
    345      const __m128i cmpA = _mm_cmpeq_epi32(A0, A1);
    346      const __m128i B0 =
    347          _mm_loadu_si128((const __m128i*)&array1[match_len + 4]);
    348      const __m128i B1 =
    349          _mm_loadu_si128((const __m128i*)&array2[match_len + 4]);
    350      if (_mm_movemask_epi8(cmpA) != 0xffff) break;
    351      match_len += 4;
    352 
    353      {
    354        const __m128i cmpB = _mm_cmpeq_epi32(B0, B1);
    355        A0 = _mm_loadu_si128((const __m128i*)&array1[match_len + 4]);
    356        A1 = _mm_loadu_si128((const __m128i*)&array2[match_len + 4]);
    357        if (_mm_movemask_epi8(cmpB) != 0xffff) break;
    358        match_len += 4;
    359      }
    360    } while (match_len + 12 < length);
    361  } else {
    362    match_len = 0;
    363    // Unroll the potential first two loops.
    364    if (length >= 4 &&
    365        _mm_movemask_epi8(_mm_cmpeq_epi32(
    366            _mm_loadu_si128((const __m128i*)&array1[0]),
    367            _mm_loadu_si128((const __m128i*)&array2[0]))) == 0xffff) {
    368      match_len = 4;
    369      if (length >= 8 &&
    370          _mm_movemask_epi8(_mm_cmpeq_epi32(
    371              _mm_loadu_si128((const __m128i*)&array1[4]),
    372              _mm_loadu_si128((const __m128i*)&array2[4]))) == 0xffff) {
    373        match_len = 8;
    374      }
    375    }
    376  }
    377 
    378  while (match_len < length && array1[match_len] == array2[match_len]) {
    379    ++match_len;
    380  }
    381  return match_len;
    382 }
    383 
    384 // Bundles multiple (1, 2, 4 or 8) pixels into a single pixel.
    385 static void BundleColorMap_SSE2(const uint8_t* WEBP_RESTRICT const row,
    386                                int width, int xbits,
    387                                uint32_t* WEBP_RESTRICT dst) {
    388  int x;
    389  assert(xbits >= 0);
    390  assert(xbits <= 3);
    391  switch (xbits) {
    392    case 0: {
    393      const __m128i ff = _mm_set1_epi16((short)0xff00);
    394      const __m128i zero = _mm_setzero_si128();
    395      // Store 0xff000000 | (row[x] << 8).
    396      for (x = 0; x + 16 <= width; x += 16, dst += 16) {
    397        const __m128i in = _mm_loadu_si128((const __m128i*)&row[x]);
    398        const __m128i in_lo = _mm_unpacklo_epi8(zero, in);
    399        const __m128i dst0 = _mm_unpacklo_epi16(in_lo, ff);
    400        const __m128i dst1 = _mm_unpackhi_epi16(in_lo, ff);
    401        const __m128i in_hi = _mm_unpackhi_epi8(zero, in);
    402        const __m128i dst2 = _mm_unpacklo_epi16(in_hi, ff);
    403        const __m128i dst3 = _mm_unpackhi_epi16(in_hi, ff);
    404        _mm_storeu_si128((__m128i*)&dst[0], dst0);
    405        _mm_storeu_si128((__m128i*)&dst[4], dst1);
    406        _mm_storeu_si128((__m128i*)&dst[8], dst2);
    407        _mm_storeu_si128((__m128i*)&dst[12], dst3);
    408      }
    409      break;
    410    }
    411    case 1: {
    412      const __m128i ff = _mm_set1_epi16((short)0xff00);
    413      const __m128i mul = _mm_set1_epi16(0x110);
    414      for (x = 0; x + 16 <= width; x += 16, dst += 8) {
    415        // 0a0b | (where a/b are 4 bits).
    416        const __m128i in = _mm_loadu_si128((const __m128i*)&row[x]);
    417        const __m128i tmp = _mm_mullo_epi16(in, mul);  // aba0
    418        const __m128i pack = _mm_and_si128(tmp, ff);   // ab00
    419        const __m128i dst0 = _mm_unpacklo_epi16(pack, ff);
    420        const __m128i dst1 = _mm_unpackhi_epi16(pack, ff);
    421        _mm_storeu_si128((__m128i*)&dst[0], dst0);
    422        _mm_storeu_si128((__m128i*)&dst[4], dst1);
    423      }
    424      break;
    425    }
    426    case 2: {
    427      const __m128i mask_or = _mm_set1_epi32((int)0xff000000);
    428      const __m128i mul_cst = _mm_set1_epi16(0x0104);
    429      const __m128i mask_mul = _mm_set1_epi16(0x0f00);
    430      for (x = 0; x + 16 <= width; x += 16, dst += 4) {
    431        // 000a000b000c000d | (where a/b/c/d are 2 bits).
    432        const __m128i in = _mm_loadu_si128((const __m128i*)&row[x]);
    433        const __m128i mul = _mm_mullo_epi16(in, mul_cst);  // 00ab00b000cd00d0
    434        const __m128i tmp = _mm_and_si128(mul, mask_mul);  // 00ab000000cd0000
    435        const __m128i shift = _mm_srli_epi32(tmp, 12);     // 00000000ab000000
    436        const __m128i pack = _mm_or_si128(shift, tmp);     // 00000000abcd0000
    437        // Convert to 0xff00**00.
    438        const __m128i res = _mm_or_si128(pack, mask_or);
    439        _mm_storeu_si128((__m128i*)dst, res);
    440      }
    441      break;
    442    }
    443    default: {
    444      assert(xbits == 3);
    445      for (x = 0; x + 16 <= width; x += 16, dst += 2) {
    446        // 0000000a00000000b... | (where a/b are 1 bit).
    447        const __m128i in = _mm_loadu_si128((const __m128i*)&row[x]);
    448        const __m128i shift = _mm_slli_epi64(in, 7);
    449        const uint32_t move = _mm_movemask_epi8(shift);
    450        dst[0] = 0xff000000 | ((move & 0xff) << 8);
    451        dst[1] = 0xff000000 | (move & 0xff00);
    452      }
    453      break;
    454    }
    455  }
    456  if (x != width) {
    457    VP8LBundleColorMap_C(row + x, width - x, xbits, dst);
    458  }
    459 }
    460 
    461 //------------------------------------------------------------------------------
    462 // Batch version of Predictor Transform subtraction
    463 
    464 static WEBP_INLINE void Average2_m128i(const __m128i* const a0,
    465                                       const __m128i* const a1,
    466                                       __m128i* const avg) {
    467  // (a + b) >> 1 = ((a + b + 1) >> 1) - ((a ^ b) & 1)
    468  const __m128i ones = _mm_set1_epi8(1);
    469  const __m128i avg1 = _mm_avg_epu8(*a0, *a1);
    470  const __m128i one = _mm_and_si128(_mm_xor_si128(*a0, *a1), ones);
    471  *avg = _mm_sub_epi8(avg1, one);
    472 }
    473 
    474 // Predictor0: ARGB_BLACK.
    475 static void PredictorSub0_SSE2(const uint32_t* in, const uint32_t* upper,
    476                               int num_pixels, uint32_t* WEBP_RESTRICT out) {
    477  int i;
    478  const __m128i black = _mm_set1_epi32((int)ARGB_BLACK);
    479  for (i = 0; i + 4 <= num_pixels; i += 4) {
    480    const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);
    481    const __m128i res = _mm_sub_epi8(src, black);
    482    _mm_storeu_si128((__m128i*)&out[i], res);
    483  }
    484  if (i != num_pixels) {
    485    VP8LPredictorsSub_C[0](in + i, NULL, num_pixels - i, out + i);
    486  }
    487  (void)upper;
    488 }
    489 
    490 #define GENERATE_PREDICTOR_1(X, IN)                                         \
    491  static void PredictorSub##X##_SSE2(const uint32_t* const in,              \
    492                                     const uint32_t* const upper,           \
    493                                     int num_pixels,                        \
    494                                     uint32_t* WEBP_RESTRICT const out) {   \
    495    int i;                                                                  \
    496    for (i = 0; i + 4 <= num_pixels; i += 4) {                              \
    497      const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);          \
    498      const __m128i pred = _mm_loadu_si128((const __m128i*)&(IN));          \
    499      const __m128i res = _mm_sub_epi8(src, pred);                          \
    500      _mm_storeu_si128((__m128i*)&out[i], res);                             \
    501    }                                                                       \
    502    if (i != num_pixels) {                                                  \
    503      VP8LPredictorsSub_C[(X)](in + i, WEBP_OFFSET_PTR(upper, i),           \
    504                               num_pixels - i, out + i);                    \
    505    }                                                                       \
    506  }
    507 
    508 GENERATE_PREDICTOR_1(1, in[i - 1])       // Predictor1: L
    509 GENERATE_PREDICTOR_1(2, upper[i])        // Predictor2: T
    510 GENERATE_PREDICTOR_1(3, upper[i + 1])    // Predictor3: TR
    511 GENERATE_PREDICTOR_1(4, upper[i - 1])    // Predictor4: TL
    512 #undef GENERATE_PREDICTOR_1
    513 
    514 // Predictor5: avg2(avg2(L, TR), T)
    515 static void PredictorSub5_SSE2(const uint32_t* in, const uint32_t* upper,
    516                               int num_pixels, uint32_t* WEBP_RESTRICT out) {
    517  int i;
    518  for (i = 0; i + 4 <= num_pixels; i += 4) {
    519    const __m128i L = _mm_loadu_si128((const __m128i*)&in[i - 1]);
    520    const __m128i T = _mm_loadu_si128((const __m128i*)&upper[i]);
    521    const __m128i TR = _mm_loadu_si128((const __m128i*)&upper[i + 1]);
    522    const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);
    523    __m128i avg, pred, res;
    524    Average2_m128i(&L, &TR, &avg);
    525    Average2_m128i(&avg, &T, &pred);
    526    res = _mm_sub_epi8(src, pred);
    527    _mm_storeu_si128((__m128i*)&out[i], res);
    528  }
    529  if (i != num_pixels) {
    530    VP8LPredictorsSub_C[5](in + i, upper + i, num_pixels - i, out + i);
    531  }
    532 }
    533 
    534 #define GENERATE_PREDICTOR_2(X, A, B)                                         \
    535 static void PredictorSub##X##_SSE2(const uint32_t* in, const uint32_t* upper, \
    536                                   int num_pixels,                            \
    537                                   uint32_t* WEBP_RESTRICT out) {             \
    538  int i;                                                                      \
    539  for (i = 0; i + 4 <= num_pixels; i += 4) {                                  \
    540    const __m128i tA = _mm_loadu_si128((const __m128i*)&(A));                 \
    541    const __m128i tB = _mm_loadu_si128((const __m128i*)&(B));                 \
    542    const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);              \
    543    __m128i pred, res;                                                        \
    544    Average2_m128i(&tA, &tB, &pred);                                          \
    545    res = _mm_sub_epi8(src, pred);                                            \
    546    _mm_storeu_si128((__m128i*)&out[i], res);                                 \
    547  }                                                                           \
    548  if (i != num_pixels) {                                                      \
    549    VP8LPredictorsSub_C[(X)](in + i, upper + i, num_pixels - i, out + i);     \
    550  }                                                                           \
    551 }
    552 
    553 GENERATE_PREDICTOR_2(6, in[i - 1], upper[i - 1])   // Predictor6: avg(L, TL)
    554 GENERATE_PREDICTOR_2(7, in[i - 1], upper[i])       // Predictor7: avg(L, T)
    555 GENERATE_PREDICTOR_2(8, upper[i - 1], upper[i])    // Predictor8: avg(TL, T)
    556 GENERATE_PREDICTOR_2(9, upper[i], upper[i + 1])    // Predictor9: average(T, TR)
    557 #undef GENERATE_PREDICTOR_2
    558 
    559 // Predictor10: avg(avg(L,TL), avg(T, TR)).
    560 static void PredictorSub10_SSE2(const uint32_t* in, const uint32_t* upper,
    561                                int num_pixels, uint32_t* WEBP_RESTRICT out) {
    562  int i;
    563  for (i = 0; i + 4 <= num_pixels; i += 4) {
    564    const __m128i L = _mm_loadu_si128((const __m128i*)&in[i - 1]);
    565    const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);
    566    const __m128i TL = _mm_loadu_si128((const __m128i*)&upper[i - 1]);
    567    const __m128i T = _mm_loadu_si128((const __m128i*)&upper[i]);
    568    const __m128i TR = _mm_loadu_si128((const __m128i*)&upper[i + 1]);
    569    __m128i avgTTR, avgLTL, avg, res;
    570    Average2_m128i(&T, &TR, &avgTTR);
    571    Average2_m128i(&L, &TL, &avgLTL);
    572    Average2_m128i(&avgTTR, &avgLTL, &avg);
    573    res = _mm_sub_epi8(src, avg);
    574    _mm_storeu_si128((__m128i*)&out[i], res);
    575  }
    576  if (i != num_pixels) {
    577    VP8LPredictorsSub_C[10](in + i, upper + i, num_pixels - i, out + i);
    578  }
    579 }
    580 
    581 // Predictor11: select.
    582 static void GetSumAbsDiff32_SSE2(const __m128i* const A, const __m128i* const B,
    583                                 __m128i* const out) {
    584  // We can unpack with any value on the upper 32 bits, provided it's the same
    585  // on both operands (to that their sum of abs diff is zero). Here we use *A.
    586  const __m128i A_lo = _mm_unpacklo_epi32(*A, *A);
    587  const __m128i B_lo = _mm_unpacklo_epi32(*B, *A);
    588  const __m128i A_hi = _mm_unpackhi_epi32(*A, *A);
    589  const __m128i B_hi = _mm_unpackhi_epi32(*B, *A);
    590  const __m128i s_lo = _mm_sad_epu8(A_lo, B_lo);
    591  const __m128i s_hi = _mm_sad_epu8(A_hi, B_hi);
    592  *out = _mm_packs_epi32(s_lo, s_hi);
    593 }
    594 
    595 static void PredictorSub11_SSE2(const uint32_t* in, const uint32_t* upper,
    596                                int num_pixels, uint32_t* WEBP_RESTRICT out) {
    597  int i;
    598  for (i = 0; i + 4 <= num_pixels; i += 4) {
    599    const __m128i L = _mm_loadu_si128((const __m128i*)&in[i - 1]);
    600    const __m128i T = _mm_loadu_si128((const __m128i*)&upper[i]);
    601    const __m128i TL = _mm_loadu_si128((const __m128i*)&upper[i - 1]);
    602    const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);
    603    __m128i pa, pb;
    604    GetSumAbsDiff32_SSE2(&T, &TL, &pa);   // pa = sum |T-TL|
    605    GetSumAbsDiff32_SSE2(&L, &TL, &pb);   // pb = sum |L-TL|
    606    {
    607      const __m128i mask = _mm_cmpgt_epi32(pb, pa);
    608      const __m128i A = _mm_and_si128(mask, L);
    609      const __m128i B = _mm_andnot_si128(mask, T);
    610      const __m128i pred = _mm_or_si128(A, B);    // pred = (L > T)? L : T
    611      const __m128i res = _mm_sub_epi8(src, pred);
    612      _mm_storeu_si128((__m128i*)&out[i], res);
    613    }
    614  }
    615  if (i != num_pixels) {
    616    VP8LPredictorsSub_C[11](in + i, upper + i, num_pixels - i, out + i);
    617  }
    618 }
    619 
    620 // Predictor12: ClampedSubSubtractFull.
    621 static void PredictorSub12_SSE2(const uint32_t* in, const uint32_t* upper,
    622                                int num_pixels, uint32_t* WEBP_RESTRICT out) {
    623  int i;
    624  const __m128i zero = _mm_setzero_si128();
    625  for (i = 0; i + 4 <= num_pixels; i += 4) {
    626    const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);
    627    const __m128i L = _mm_loadu_si128((const __m128i*)&in[i - 1]);
    628    const __m128i L_lo = _mm_unpacklo_epi8(L, zero);
    629    const __m128i L_hi = _mm_unpackhi_epi8(L, zero);
    630    const __m128i T = _mm_loadu_si128((const __m128i*)&upper[i]);
    631    const __m128i T_lo = _mm_unpacklo_epi8(T, zero);
    632    const __m128i T_hi = _mm_unpackhi_epi8(T, zero);
    633    const __m128i TL = _mm_loadu_si128((const __m128i*)&upper[i - 1]);
    634    const __m128i TL_lo = _mm_unpacklo_epi8(TL, zero);
    635    const __m128i TL_hi = _mm_unpackhi_epi8(TL, zero);
    636    const __m128i diff_lo = _mm_sub_epi16(T_lo, TL_lo);
    637    const __m128i diff_hi = _mm_sub_epi16(T_hi, TL_hi);
    638    const __m128i pred_lo = _mm_add_epi16(L_lo, diff_lo);
    639    const __m128i pred_hi = _mm_add_epi16(L_hi, diff_hi);
    640    const __m128i pred = _mm_packus_epi16(pred_lo, pred_hi);
    641    const __m128i res = _mm_sub_epi8(src, pred);
    642    _mm_storeu_si128((__m128i*)&out[i], res);
    643  }
    644  if (i != num_pixels) {
    645    VP8LPredictorsSub_C[12](in + i, upper + i, num_pixels - i, out + i);
    646  }
    647 }
    648 
    649 // Predictors13: ClampedAddSubtractHalf
    650 static void PredictorSub13_SSE2(const uint32_t* in, const uint32_t* upper,
    651                                int num_pixels, uint32_t* WEBP_RESTRICT out) {
    652  int i;
    653  const __m128i zero = _mm_setzero_si128();
    654  for (i = 0; i + 4 <= num_pixels; i += 4) {
    655    const __m128i L = _mm_loadu_si128((const __m128i*)&in[i - 1]);
    656    const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]);
    657    const __m128i T = _mm_loadu_si128((const __m128i*)&upper[i]);
    658    const __m128i TL = _mm_loadu_si128((const __m128i*)&upper[i - 1]);
    659    __m128i A4_lo, A4_hi;
    660    // lo.
    661    {
    662      const __m128i L_lo = _mm_unpacklo_epi8(L, zero);
    663      const __m128i T_lo = _mm_unpacklo_epi8(T, zero);
    664      const __m128i TL_lo = _mm_unpacklo_epi8(TL, zero);
    665      const __m128i sum_lo = _mm_add_epi16(T_lo, L_lo);
    666      const __m128i avg_lo = _mm_srli_epi16(sum_lo, 1);
    667      const __m128i A1_lo = _mm_sub_epi16(avg_lo, TL_lo);
    668      const __m128i bit_fix_lo = _mm_cmpgt_epi16(TL_lo, avg_lo);
    669      const __m128i A2_lo = _mm_sub_epi16(A1_lo, bit_fix_lo);
    670      const __m128i A3_lo = _mm_srai_epi16(A2_lo, 1);
    671      A4_lo = _mm_add_epi16(avg_lo, A3_lo);
    672    }
    673    // hi.
    674    {
    675      const __m128i L_hi = _mm_unpackhi_epi8(L, zero);
    676      const __m128i T_hi = _mm_unpackhi_epi8(T, zero);
    677      const __m128i TL_hi = _mm_unpackhi_epi8(TL, zero);
    678      const __m128i sum_hi = _mm_add_epi16(T_hi, L_hi);
    679      const __m128i avg_hi = _mm_srli_epi16(sum_hi, 1);
    680      const __m128i A1_hi = _mm_sub_epi16(avg_hi, TL_hi);
    681      const __m128i bit_fix_hi = _mm_cmpgt_epi16(TL_hi, avg_hi);
    682      const __m128i A2_hi = _mm_sub_epi16(A1_hi, bit_fix_hi);
    683      const __m128i A3_hi = _mm_srai_epi16(A2_hi, 1);
    684      A4_hi = _mm_add_epi16(avg_hi, A3_hi);
    685    }
    686    {
    687      const __m128i pred = _mm_packus_epi16(A4_lo, A4_hi);
    688      const __m128i res = _mm_sub_epi8(src, pred);
    689      _mm_storeu_si128((__m128i*)&out[i], res);
    690    }
    691  }
    692  if (i != num_pixels) {
    693    VP8LPredictorsSub_C[13](in + i, upper + i, num_pixels - i, out + i);
    694  }
    695 }
    696 
    697 //------------------------------------------------------------------------------
    698 // Entry point
    699 
    700 extern void VP8LEncDspInitSSE2(void);
    701 
    702 WEBP_TSAN_IGNORE_FUNCTION void VP8LEncDspInitSSE2(void) {
    703  VP8LSubtractGreenFromBlueAndRed = SubtractGreenFromBlueAndRed_SSE2;
    704  VP8LTransformColor = TransformColor_SSE2;
    705  VP8LCollectColorBlueTransforms = CollectColorBlueTransforms_SSE2;
    706  VP8LCollectColorRedTransforms = CollectColorRedTransforms_SSE2;
    707  VP8LAddVector = AddVector_SSE2;
    708  VP8LAddVectorEq = AddVectorEq_SSE2;
    709 #if !defined(DONT_USE_COMBINED_SHANNON_ENTROPY_SSE2_FUNC)
    710  VP8LCombinedShannonEntropy = CombinedShannonEntropy_SSE2;
    711 #endif
    712  VP8LVectorMismatch = VectorMismatch_SSE2;
    713  VP8LBundleColorMap = BundleColorMap_SSE2;
    714 
    715  VP8LPredictorsSub[0] = PredictorSub0_SSE2;
    716  VP8LPredictorsSub[1] = PredictorSub1_SSE2;
    717  VP8LPredictorsSub[2] = PredictorSub2_SSE2;
    718  VP8LPredictorsSub[3] = PredictorSub3_SSE2;
    719  VP8LPredictorsSub[4] = PredictorSub4_SSE2;
    720  VP8LPredictorsSub[5] = PredictorSub5_SSE2;
    721  VP8LPredictorsSub[6] = PredictorSub6_SSE2;
    722  VP8LPredictorsSub[7] = PredictorSub7_SSE2;
    723  VP8LPredictorsSub[8] = PredictorSub8_SSE2;
    724  VP8LPredictorsSub[9] = PredictorSub9_SSE2;
    725  VP8LPredictorsSub[10] = PredictorSub10_SSE2;
    726  VP8LPredictorsSub[11] = PredictorSub11_SSE2;
    727  VP8LPredictorsSub[12] = PredictorSub12_SSE2;
    728  VP8LPredictorsSub[13] = PredictorSub13_SSE2;
    729  VP8LPredictorsSub[14] = PredictorSub0_SSE2;  // <- padding security sentinels
    730  VP8LPredictorsSub[15] = PredictorSub0_SSE2;
    731 
    732  // SSE exports for AVX and above.
    733  VP8LSubtractGreenFromBlueAndRed_SSE = SubtractGreenFromBlueAndRed_SSE2;
    734  VP8LTransformColor_SSE = TransformColor_SSE2;
    735  VP8LCollectColorBlueTransforms_SSE = CollectColorBlueTransforms_SSE2;
    736  VP8LCollectColorRedTransforms_SSE = CollectColorRedTransforms_SSE2;
    737  VP8LBundleColorMap_SSE = BundleColorMap_SSE2;
    738 
    739  memcpy(VP8LPredictorsSub_SSE, VP8LPredictorsSub, sizeof(VP8LPredictorsSub));
    740 }
    741 
    742 #else  // !WEBP_USE_SSE2
    743 
    744 WEBP_DSP_INIT_STUB(VP8LEncDspInitSSE2)
    745 
    746 #endif  // WEBP_USE_SSE2