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      1 // Copyright 2011 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 version of speed-critical encoding functions.
     11 //
     12 // Author: Christian Duvivier (cduvivier (at) google.com)
     13 
     14 #include "./dsp.h"
     15 
     16 #if defined(WEBP_USE_SSE2)
     17 #include <stdlib.h>  // for abs()
     18 #include <emmintrin.h>
     19 
     20 #include "../enc/cost.h"
     21 #include "../enc/vp8enci.h"
     22 
     23 //------------------------------------------------------------------------------
     24 // Quite useful macro for debugging. Left here for convenience.
     25 
     26 #if 0
     27 #include <stdio.h>
     28 static void PrintReg(const __m128i r, const char* const name, int size) {
     29   int n;
     30   union {
     31     __m128i r;
     32     uint8_t i8[16];
     33     uint16_t i16[8];
     34     uint32_t i32[4];
     35     uint64_t i64[2];
     36   } tmp;
     37   tmp.r = r;
     38   fprintf(stderr, "%s\t: ", name);
     39   if (size == 8) {
     40     for (n = 0; n < 16; ++n) fprintf(stderr, "%.2x ", tmp.i8[n]);
     41   } else if (size == 16) {
     42     for (n = 0; n < 8; ++n) fprintf(stderr, "%.4x ", tmp.i16[n]);
     43   } else if (size == 32) {
     44     for (n = 0; n < 4; ++n) fprintf(stderr, "%.8x ", tmp.i32[n]);
     45   } else {
     46     for (n = 0; n < 2; ++n) fprintf(stderr, "%.16lx ", tmp.i64[n]);
     47   }
     48   fprintf(stderr, "\n");
     49 }
     50 #endif
     51 
     52 //------------------------------------------------------------------------------
     53 // Transforms (Paragraph 14.4)
     54 
     55 // Does one or two inverse transforms.
     56 static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst,
     57                        int do_two) {
     58   // This implementation makes use of 16-bit fixed point versions of two
     59   // multiply constants:
     60   //    K1 = sqrt(2) * cos (pi/8) ~= 85627 / 2^16
     61   //    K2 = sqrt(2) * sin (pi/8) ~= 35468 / 2^16
     62   //
     63   // To be able to use signed 16-bit integers, we use the following trick to
     64   // have constants within range:
     65   // - Associated constants are obtained by subtracting the 16-bit fixed point
     66   //   version of one:
     67   //      k = K - (1 << 16)  =>  K = k + (1 << 16)
     68   //      K1 = 85267  =>  k1 =  20091
     69   //      K2 = 35468  =>  k2 = -30068
     70   // - The multiplication of a variable by a constant become the sum of the
     71   //   variable and the multiplication of that variable by the associated
     72   //   constant:
     73   //      (x * K) >> 16 = (x * (k + (1 << 16))) >> 16 = ((x * k ) >> 16) + x
     74   const __m128i k1 = _mm_set1_epi16(20091);
     75   const __m128i k2 = _mm_set1_epi16(-30068);
     76   __m128i T0, T1, T2, T3;
     77 
     78   // Load and concatenate the transform coefficients (we'll do two inverse
     79   // transforms in parallel). In the case of only one inverse transform, the
     80   // second half of the vectors will just contain random value we'll never
     81   // use nor store.
     82   __m128i in0, in1, in2, in3;
     83   {
     84     in0 = _mm_loadl_epi64((const __m128i*)&in[0]);
     85     in1 = _mm_loadl_epi64((const __m128i*)&in[4]);
     86     in2 = _mm_loadl_epi64((const __m128i*)&in[8]);
     87     in3 = _mm_loadl_epi64((const __m128i*)&in[12]);
     88     // a00 a10 a20 a30   x x x x
     89     // a01 a11 a21 a31   x x x x
     90     // a02 a12 a22 a32   x x x x
     91     // a03 a13 a23 a33   x x x x
     92     if (do_two) {
     93       const __m128i inB0 = _mm_loadl_epi64((const __m128i*)&in[16]);
     94       const __m128i inB1 = _mm_loadl_epi64((const __m128i*)&in[20]);
     95       const __m128i inB2 = _mm_loadl_epi64((const __m128i*)&in[24]);
     96       const __m128i inB3 = _mm_loadl_epi64((const __m128i*)&in[28]);
     97       in0 = _mm_unpacklo_epi64(in0, inB0);
     98       in1 = _mm_unpacklo_epi64(in1, inB1);
     99       in2 = _mm_unpacklo_epi64(in2, inB2);
    100       in3 = _mm_unpacklo_epi64(in3, inB3);
    101       // a00 a10 a20 a30   b00 b10 b20 b30
    102       // a01 a11 a21 a31   b01 b11 b21 b31
    103       // a02 a12 a22 a32   b02 b12 b22 b32
    104       // a03 a13 a23 a33   b03 b13 b23 b33
    105     }
    106   }
    107 
    108   // Vertical pass and subsequent transpose.
    109   {
    110     // First pass, c and d calculations are longer because of the "trick"
    111     // multiplications.
    112     const __m128i a = _mm_add_epi16(in0, in2);
    113     const __m128i b = _mm_sub_epi16(in0, in2);
    114     // c = MUL(in1, K2) - MUL(in3, K1) = MUL(in1, k2) - MUL(in3, k1) + in1 - in3
    115     const __m128i c1 = _mm_mulhi_epi16(in1, k2);
    116     const __m128i c2 = _mm_mulhi_epi16(in3, k1);
    117     const __m128i c3 = _mm_sub_epi16(in1, in3);
    118     const __m128i c4 = _mm_sub_epi16(c1, c2);
    119     const __m128i c = _mm_add_epi16(c3, c4);
    120     // d = MUL(in1, K1) + MUL(in3, K2) = MUL(in1, k1) + MUL(in3, k2) + in1 + in3
    121     const __m128i d1 = _mm_mulhi_epi16(in1, k1);
    122     const __m128i d2 = _mm_mulhi_epi16(in3, k2);
    123     const __m128i d3 = _mm_add_epi16(in1, in3);
    124     const __m128i d4 = _mm_add_epi16(d1, d2);
    125     const __m128i d = _mm_add_epi16(d3, d4);
    126 
    127     // Second pass.
    128     const __m128i tmp0 = _mm_add_epi16(a, d);
    129     const __m128i tmp1 = _mm_add_epi16(b, c);
    130     const __m128i tmp2 = _mm_sub_epi16(b, c);
    131     const __m128i tmp3 = _mm_sub_epi16(a, d);
    132 
    133     // Transpose the two 4x4.
    134     // a00 a01 a02 a03   b00 b01 b02 b03
    135     // a10 a11 a12 a13   b10 b11 b12 b13
    136     // a20 a21 a22 a23   b20 b21 b22 b23
    137     // a30 a31 a32 a33   b30 b31 b32 b33
    138     const __m128i transpose0_0 = _mm_unpacklo_epi16(tmp0, tmp1);
    139     const __m128i transpose0_1 = _mm_unpacklo_epi16(tmp2, tmp3);
    140     const __m128i transpose0_2 = _mm_unpackhi_epi16(tmp0, tmp1);
    141     const __m128i transpose0_3 = _mm_unpackhi_epi16(tmp2, tmp3);
    142     // a00 a10 a01 a11   a02 a12 a03 a13
    143     // a20 a30 a21 a31   a22 a32 a23 a33
    144     // b00 b10 b01 b11   b02 b12 b03 b13
    145     // b20 b30 b21 b31   b22 b32 b23 b33
    146     const __m128i transpose1_0 = _mm_unpacklo_epi32(transpose0_0, transpose0_1);
    147     const __m128i transpose1_1 = _mm_unpacklo_epi32(transpose0_2, transpose0_3);
    148     const __m128i transpose1_2 = _mm_unpackhi_epi32(transpose0_0, transpose0_1);
    149     const __m128i transpose1_3 = _mm_unpackhi_epi32(transpose0_2, transpose0_3);
    150     // a00 a10 a20 a30 a01 a11 a21 a31
    151     // b00 b10 b20 b30 b01 b11 b21 b31
    152     // a02 a12 a22 a32 a03 a13 a23 a33
    153     // b02 b12 a22 b32 b03 b13 b23 b33
    154     T0 = _mm_unpacklo_epi64(transpose1_0, transpose1_1);
    155     T1 = _mm_unpackhi_epi64(transpose1_0, transpose1_1);
    156     T2 = _mm_unpacklo_epi64(transpose1_2, transpose1_3);
    157     T3 = _mm_unpackhi_epi64(transpose1_2, transpose1_3);
    158     // a00 a10 a20 a30   b00 b10 b20 b30
    159     // a01 a11 a21 a31   b01 b11 b21 b31
    160     // a02 a12 a22 a32   b02 b12 b22 b32
    161     // a03 a13 a23 a33   b03 b13 b23 b33
    162   }
    163 
    164   // Horizontal pass and subsequent transpose.
    165   {
    166     // First pass, c and d calculations are longer because of the "trick"
    167     // multiplications.
    168     const __m128i four = _mm_set1_epi16(4);
    169     const __m128i dc = _mm_add_epi16(T0, four);
    170     const __m128i a =  _mm_add_epi16(dc, T2);
    171     const __m128i b =  _mm_sub_epi16(dc, T2);
    172     // c = MUL(T1, K2) - MUL(T3, K1) = MUL(T1, k2) - MUL(T3, k1) + T1 - T3
    173     const __m128i c1 = _mm_mulhi_epi16(T1, k2);
    174     const __m128i c2 = _mm_mulhi_epi16(T3, k1);
    175     const __m128i c3 = _mm_sub_epi16(T1, T3);
    176     const __m128i c4 = _mm_sub_epi16(c1, c2);
    177     const __m128i c = _mm_add_epi16(c3, c4);
    178     // d = MUL(T1, K1) + MUL(T3, K2) = MUL(T1, k1) + MUL(T3, k2) + T1 + T3
    179     const __m128i d1 = _mm_mulhi_epi16(T1, k1);
    180     const __m128i d2 = _mm_mulhi_epi16(T3, k2);
    181     const __m128i d3 = _mm_add_epi16(T1, T3);
    182     const __m128i d4 = _mm_add_epi16(d1, d2);
    183     const __m128i d = _mm_add_epi16(d3, d4);
    184 
    185     // Second pass.
    186     const __m128i tmp0 = _mm_add_epi16(a, d);
    187     const __m128i tmp1 = _mm_add_epi16(b, c);
    188     const __m128i tmp2 = _mm_sub_epi16(b, c);
    189     const __m128i tmp3 = _mm_sub_epi16(a, d);
    190     const __m128i shifted0 = _mm_srai_epi16(tmp0, 3);
    191     const __m128i shifted1 = _mm_srai_epi16(tmp1, 3);
    192     const __m128i shifted2 = _mm_srai_epi16(tmp2, 3);
    193     const __m128i shifted3 = _mm_srai_epi16(tmp3, 3);
    194 
    195     // Transpose the two 4x4.
    196     // a00 a01 a02 a03   b00 b01 b02 b03
    197     // a10 a11 a12 a13   b10 b11 b12 b13
    198     // a20 a21 a22 a23   b20 b21 b22 b23
    199     // a30 a31 a32 a33   b30 b31 b32 b33
    200     const __m128i transpose0_0 = _mm_unpacklo_epi16(shifted0, shifted1);
    201     const __m128i transpose0_1 = _mm_unpacklo_epi16(shifted2, shifted3);
    202     const __m128i transpose0_2 = _mm_unpackhi_epi16(shifted0, shifted1);
    203     const __m128i transpose0_3 = _mm_unpackhi_epi16(shifted2, shifted3);
    204     // a00 a10 a01 a11   a02 a12 a03 a13
    205     // a20 a30 a21 a31   a22 a32 a23 a33
    206     // b00 b10 b01 b11   b02 b12 b03 b13
    207     // b20 b30 b21 b31   b22 b32 b23 b33
    208     const __m128i transpose1_0 = _mm_unpacklo_epi32(transpose0_0, transpose0_1);
    209     const __m128i transpose1_1 = _mm_unpacklo_epi32(transpose0_2, transpose0_3);
    210     const __m128i transpose1_2 = _mm_unpackhi_epi32(transpose0_0, transpose0_1);
    211     const __m128i transpose1_3 = _mm_unpackhi_epi32(transpose0_2, transpose0_3);
    212     // a00 a10 a20 a30 a01 a11 a21 a31
    213     // b00 b10 b20 b30 b01 b11 b21 b31
    214     // a02 a12 a22 a32 a03 a13 a23 a33
    215     // b02 b12 a22 b32 b03 b13 b23 b33
    216     T0 = _mm_unpacklo_epi64(transpose1_0, transpose1_1);
    217     T1 = _mm_unpackhi_epi64(transpose1_0, transpose1_1);
    218     T2 = _mm_unpacklo_epi64(transpose1_2, transpose1_3);
    219     T3 = _mm_unpackhi_epi64(transpose1_2, transpose1_3);
    220     // a00 a10 a20 a30   b00 b10 b20 b30
    221     // a01 a11 a21 a31   b01 b11 b21 b31
    222     // a02 a12 a22 a32   b02 b12 b22 b32
    223     // a03 a13 a23 a33   b03 b13 b23 b33
    224   }
    225 
    226   // Add inverse transform to 'ref' and store.
    227   {
    228     const __m128i zero = _mm_setzero_si128();
    229     // Load the reference(s).
    230     __m128i ref0, ref1, ref2, ref3;
    231     if (do_two) {
    232       // Load eight bytes/pixels per line.
    233       ref0 = _mm_loadl_epi64((const __m128i*)&ref[0 * BPS]);
    234       ref1 = _mm_loadl_epi64((const __m128i*)&ref[1 * BPS]);
    235       ref2 = _mm_loadl_epi64((const __m128i*)&ref[2 * BPS]);
    236       ref3 = _mm_loadl_epi64((const __m128i*)&ref[3 * BPS]);
    237     } else {
    238       // Load four bytes/pixels per line.
    239       ref0 = _mm_cvtsi32_si128(WebPMemToUint32(&ref[0 * BPS]));
    240       ref1 = _mm_cvtsi32_si128(WebPMemToUint32(&ref[1 * BPS]));
    241       ref2 = _mm_cvtsi32_si128(WebPMemToUint32(&ref[2 * BPS]));
    242       ref3 = _mm_cvtsi32_si128(WebPMemToUint32(&ref[3 * BPS]));
    243     }
    244     // Convert to 16b.
    245     ref0 = _mm_unpacklo_epi8(ref0, zero);
    246     ref1 = _mm_unpacklo_epi8(ref1, zero);
    247     ref2 = _mm_unpacklo_epi8(ref2, zero);
    248     ref3 = _mm_unpacklo_epi8(ref3, zero);
    249     // Add the inverse transform(s).
    250     ref0 = _mm_add_epi16(ref0, T0);
    251     ref1 = _mm_add_epi16(ref1, T1);
    252     ref2 = _mm_add_epi16(ref2, T2);
    253     ref3 = _mm_add_epi16(ref3, T3);
    254     // Unsigned saturate to 8b.
    255     ref0 = _mm_packus_epi16(ref0, ref0);
    256     ref1 = _mm_packus_epi16(ref1, ref1);
    257     ref2 = _mm_packus_epi16(ref2, ref2);
    258     ref3 = _mm_packus_epi16(ref3, ref3);
    259     // Store the results.
    260     if (do_two) {
    261       // Store eight bytes/pixels per line.
    262       _mm_storel_epi64((__m128i*)&dst[0 * BPS], ref0);
    263       _mm_storel_epi64((__m128i*)&dst[1 * BPS], ref1);
    264       _mm_storel_epi64((__m128i*)&dst[2 * BPS], ref2);
    265       _mm_storel_epi64((__m128i*)&dst[3 * BPS], ref3);
    266     } else {
    267       // Store four bytes/pixels per line.
    268       WebPUint32ToMem(&dst[0 * BPS], _mm_cvtsi128_si32(ref0));
    269       WebPUint32ToMem(&dst[1 * BPS], _mm_cvtsi128_si32(ref1));
    270       WebPUint32ToMem(&dst[2 * BPS], _mm_cvtsi128_si32(ref2));
    271       WebPUint32ToMem(&dst[3 * BPS], _mm_cvtsi128_si32(ref3));
    272     }
    273   }
    274 }
    275 
    276 static void FTransformPass1(const __m128i* const in01,
    277                             const __m128i* const in23,
    278                             __m128i* const out01,
    279                             __m128i* const out32) {
    280   const __m128i k937 = _mm_set1_epi32(937);
    281   const __m128i k1812 = _mm_set1_epi32(1812);
    282 
    283   const __m128i k88p = _mm_set_epi16(8, 8, 8, 8, 8, 8, 8, 8);
    284   const __m128i k88m = _mm_set_epi16(-8, 8, -8, 8, -8, 8, -8, 8);
    285   const __m128i k5352_2217p = _mm_set_epi16(2217, 5352, 2217, 5352,
    286                                             2217, 5352, 2217, 5352);
    287   const __m128i k5352_2217m = _mm_set_epi16(-5352, 2217, -5352, 2217,
    288                                             -5352, 2217, -5352, 2217);
    289 
    290   // *in01 = 00 01 10 11 02 03 12 13
    291   // *in23 = 20 21 30 31 22 23 32 33
    292   const __m128i shuf01_p = _mm_shufflehi_epi16(*in01, _MM_SHUFFLE(2, 3, 0, 1));
    293   const __m128i shuf23_p = _mm_shufflehi_epi16(*in23, _MM_SHUFFLE(2, 3, 0, 1));
    294   // 00 01 10 11 03 02 13 12
    295   // 20 21 30 31 23 22 33 32
    296   const __m128i s01 = _mm_unpacklo_epi64(shuf01_p, shuf23_p);
    297   const __m128i s32 = _mm_unpackhi_epi64(shuf01_p, shuf23_p);
    298   // 00 01 10 11 20 21 30 31
    299   // 03 02 13 12 23 22 33 32
    300   const __m128i a01 = _mm_add_epi16(s01, s32);
    301   const __m128i a32 = _mm_sub_epi16(s01, s32);
    302   // [d0 + d3 | d1 + d2 | ...] = [a0 a1 | a0' a1' | ... ]
    303   // [d0 - d3 | d1 - d2 | ...] = [a3 a2 | a3' a2' | ... ]
    304 
    305   const __m128i tmp0   = _mm_madd_epi16(a01, k88p);  // [ (a0 + a1) << 3, ... ]
    306   const __m128i tmp2   = _mm_madd_epi16(a01, k88m);  // [ (a0 - a1) << 3, ... ]
    307   const __m128i tmp1_1 = _mm_madd_epi16(a32, k5352_2217p);
    308   const __m128i tmp3_1 = _mm_madd_epi16(a32, k5352_2217m);
    309   const __m128i tmp1_2 = _mm_add_epi32(tmp1_1, k1812);
    310   const __m128i tmp3_2 = _mm_add_epi32(tmp3_1, k937);
    311   const __m128i tmp1   = _mm_srai_epi32(tmp1_2, 9);
    312   const __m128i tmp3   = _mm_srai_epi32(tmp3_2, 9);
    313   const __m128i s03    = _mm_packs_epi32(tmp0, tmp2);
    314   const __m128i s12    = _mm_packs_epi32(tmp1, tmp3);
    315   const __m128i s_lo   = _mm_unpacklo_epi16(s03, s12);   // 0 1 0 1 0 1...
    316   const __m128i s_hi   = _mm_unpackhi_epi16(s03, s12);   // 2 3 2 3 2 3
    317   const __m128i v23    = _mm_unpackhi_epi32(s_lo, s_hi);
    318   *out01 = _mm_unpacklo_epi32(s_lo, s_hi);
    319   *out32 = _mm_shuffle_epi32(v23, _MM_SHUFFLE(1, 0, 3, 2));  // 3 2 3 2 3 2..
    320 }
    321 
    322 static void FTransformPass2(const __m128i* const v01, const __m128i* const v32,
    323                             int16_t* out) {
    324   const __m128i zero = _mm_setzero_si128();
    325   const __m128i seven = _mm_set1_epi16(7);
    326   const __m128i k5352_2217 = _mm_set_epi16(5352,  2217, 5352,  2217,
    327                                            5352,  2217, 5352,  2217);
    328   const __m128i k2217_5352 = _mm_set_epi16(2217, -5352, 2217, -5352,
    329                                            2217, -5352, 2217, -5352);
    330   const __m128i k12000_plus_one = _mm_set1_epi32(12000 + (1 << 16));
    331   const __m128i k51000 = _mm_set1_epi32(51000);
    332 
    333   // Same operations are done on the (0,3) and (1,2) pairs.
    334   // a0 = v0 + v3
    335   // a1 = v1 + v2
    336   // a3 = v0 - v3
    337   // a2 = v1 - v2
    338   const __m128i a01 = _mm_add_epi16(*v01, *v32);
    339   const __m128i a32 = _mm_sub_epi16(*v01, *v32);
    340   const __m128i a11 = _mm_unpackhi_epi64(a01, a01);
    341   const __m128i a22 = _mm_unpackhi_epi64(a32, a32);
    342   const __m128i a01_plus_7 = _mm_add_epi16(a01, seven);
    343 
    344   // d0 = (a0 + a1 + 7) >> 4;
    345   // d2 = (a0 - a1 + 7) >> 4;
    346   const __m128i c0 = _mm_add_epi16(a01_plus_7, a11);
    347   const __m128i c2 = _mm_sub_epi16(a01_plus_7, a11);
    348   const __m128i d0 = _mm_srai_epi16(c0, 4);
    349   const __m128i d2 = _mm_srai_epi16(c2, 4);
    350 
    351   // f1 = ((b3 * 5352 + b2 * 2217 + 12000) >> 16)
    352   // f3 = ((b3 * 2217 - b2 * 5352 + 51000) >> 16)
    353   const __m128i b23 = _mm_unpacklo_epi16(a22, a32);
    354   const __m128i c1 = _mm_madd_epi16(b23, k5352_2217);
    355   const __m128i c3 = _mm_madd_epi16(b23, k2217_5352);
    356   const __m128i d1 = _mm_add_epi32(c1, k12000_plus_one);
    357   const __m128i d3 = _mm_add_epi32(c3, k51000);
    358   const __m128i e1 = _mm_srai_epi32(d1, 16);
    359   const __m128i e3 = _mm_srai_epi32(d3, 16);
    360   const __m128i f1 = _mm_packs_epi32(e1, e1);
    361   const __m128i f3 = _mm_packs_epi32(e3, e3);
    362   // f1 = f1 + (a3 != 0);
    363   // The compare will return (0xffff, 0) for (==0, !=0). To turn that into the
    364   // desired (0, 1), we add one earlier through k12000_plus_one.
    365   // -> f1 = f1 + 1 - (a3 == 0)
    366   const __m128i g1 = _mm_add_epi16(f1, _mm_cmpeq_epi16(a32, zero));
    367 
    368   const __m128i d0_g1 = _mm_unpacklo_epi64(d0, g1);
    369   const __m128i d2_f3 = _mm_unpacklo_epi64(d2, f3);
    370   _mm_storeu_si128((__m128i*)&out[0], d0_g1);
    371   _mm_storeu_si128((__m128i*)&out[8], d2_f3);
    372 }
    373 
    374 static void FTransform(const uint8_t* src, const uint8_t* ref, int16_t* out) {
    375   const __m128i zero = _mm_setzero_si128();
    376 
    377   // Load src and convert to 16b.
    378   const __m128i src0 = _mm_loadl_epi64((const __m128i*)&src[0 * BPS]);
    379   const __m128i src1 = _mm_loadl_epi64((const __m128i*)&src[1 * BPS]);
    380   const __m128i src2 = _mm_loadl_epi64((const __m128i*)&src[2 * BPS]);
    381   const __m128i src3 = _mm_loadl_epi64((const __m128i*)&src[3 * BPS]);
    382   const __m128i src_0 = _mm_unpacklo_epi8(src0, zero);
    383   const __m128i src_1 = _mm_unpacklo_epi8(src1, zero);
    384   const __m128i src_2 = _mm_unpacklo_epi8(src2, zero);
    385   const __m128i src_3 = _mm_unpacklo_epi8(src3, zero);
    386   // Load ref and convert to 16b.
    387   const __m128i ref0 = _mm_loadl_epi64((const __m128i*)&ref[0 * BPS]);
    388   const __m128i ref1 = _mm_loadl_epi64((const __m128i*)&ref[1 * BPS]);
    389   const __m128i ref2 = _mm_loadl_epi64((const __m128i*)&ref[2 * BPS]);
    390   const __m128i ref3 = _mm_loadl_epi64((const __m128i*)&ref[3 * BPS]);
    391   const __m128i ref_0 = _mm_unpacklo_epi8(ref0, zero);
    392   const __m128i ref_1 = _mm_unpacklo_epi8(ref1, zero);
    393   const __m128i ref_2 = _mm_unpacklo_epi8(ref2, zero);
    394   const __m128i ref_3 = _mm_unpacklo_epi8(ref3, zero);
    395   // Compute difference. -> 00 01 02 03 00 00 00 00
    396   const __m128i diff0 = _mm_sub_epi16(src_0, ref_0);
    397   const __m128i diff1 = _mm_sub_epi16(src_1, ref_1);
    398   const __m128i diff2 = _mm_sub_epi16(src_2, ref_2);
    399   const __m128i diff3 = _mm_sub_epi16(src_3, ref_3);
    400 
    401   // Unpack and shuffle
    402   // 00 01 02 03   0 0 0 0
    403   // 10 11 12 13   0 0 0 0
    404   // 20 21 22 23   0 0 0 0
    405   // 30 31 32 33   0 0 0 0
    406   const __m128i shuf01 = _mm_unpacklo_epi32(diff0, diff1);
    407   const __m128i shuf23 = _mm_unpacklo_epi32(diff2, diff3);
    408   __m128i v01, v32;
    409 
    410   // First pass
    411   FTransformPass1(&shuf01, &shuf23, &v01, &v32);
    412 
    413   // Second pass
    414   FTransformPass2(&v01, &v32, out);
    415 }
    416 
    417 static void FTransform2(const uint8_t* src, const uint8_t* ref, int16_t* out) {
    418   const __m128i zero = _mm_setzero_si128();
    419 
    420   // Load src and convert to 16b.
    421   const __m128i src0 = _mm_loadl_epi64((const __m128i*)&src[0 * BPS]);
    422   const __m128i src1 = _mm_loadl_epi64((const __m128i*)&src[1 * BPS]);
    423   const __m128i src2 = _mm_loadl_epi64((const __m128i*)&src[2 * BPS]);
    424   const __m128i src3 = _mm_loadl_epi64((const __m128i*)&src[3 * BPS]);
    425   const __m128i src_0 = _mm_unpacklo_epi8(src0, zero);
    426   const __m128i src_1 = _mm_unpacklo_epi8(src1, zero);
    427   const __m128i src_2 = _mm_unpacklo_epi8(src2, zero);
    428   const __m128i src_3 = _mm_unpacklo_epi8(src3, zero);
    429   // Load ref and convert to 16b.
    430   const __m128i ref0 = _mm_loadl_epi64((const __m128i*)&ref[0 * BPS]);
    431   const __m128i ref1 = _mm_loadl_epi64((const __m128i*)&ref[1 * BPS]);
    432   const __m128i ref2 = _mm_loadl_epi64((const __m128i*)&ref[2 * BPS]);
    433   const __m128i ref3 = _mm_loadl_epi64((const __m128i*)&ref[3 * BPS]);
    434   const __m128i ref_0 = _mm_unpacklo_epi8(ref0, zero);
    435   const __m128i ref_1 = _mm_unpacklo_epi8(ref1, zero);
    436   const __m128i ref_2 = _mm_unpacklo_epi8(ref2, zero);
    437   const __m128i ref_3 = _mm_unpacklo_epi8(ref3, zero);
    438   // Compute difference. -> 00 01 02 03  00' 01' 02' 03'
    439   const __m128i diff0 = _mm_sub_epi16(src_0, ref_0);
    440   const __m128i diff1 = _mm_sub_epi16(src_1, ref_1);
    441   const __m128i diff2 = _mm_sub_epi16(src_2, ref_2);
    442   const __m128i diff3 = _mm_sub_epi16(src_3, ref_3);
    443 
    444   // Unpack and shuffle
    445   // 00 01 02 03   0 0 0 0
    446   // 10 11 12 13   0 0 0 0
    447   // 20 21 22 23   0 0 0 0
    448   // 30 31 32 33   0 0 0 0
    449   const __m128i shuf01l = _mm_unpacklo_epi32(diff0, diff1);
    450   const __m128i shuf23l = _mm_unpacklo_epi32(diff2, diff3);
    451   const __m128i shuf01h = _mm_unpackhi_epi32(diff0, diff1);
    452   const __m128i shuf23h = _mm_unpackhi_epi32(diff2, diff3);
    453   __m128i v01l, v32l;
    454   __m128i v01h, v32h;
    455 
    456   // First pass
    457   FTransformPass1(&shuf01l, &shuf23l, &v01l, &v32l);
    458   FTransformPass1(&shuf01h, &shuf23h, &v01h, &v32h);
    459 
    460   // Second pass
    461   FTransformPass2(&v01l, &v32l, out + 0);
    462   FTransformPass2(&v01h, &v32h, out + 16);
    463 }
    464 
    465 static void FTransformWHTRow(const int16_t* const in, __m128i* const out) {
    466   const __m128i kMult1 = _mm_set_epi16(0, 0, 0, 0, 1, 1, 1, 1);
    467   const __m128i kMult2 = _mm_set_epi16(0, 0, 0, 0, -1, 1, -1, 1);
    468   const __m128i src0 = _mm_loadl_epi64((__m128i*)&in[0 * 16]);
    469   const __m128i src1 = _mm_loadl_epi64((__m128i*)&in[1 * 16]);
    470   const __m128i src2 = _mm_loadl_epi64((__m128i*)&in[2 * 16]);
    471   const __m128i src3 = _mm_loadl_epi64((__m128i*)&in[3 * 16]);
    472   const __m128i A01 = _mm_unpacklo_epi16(src0, src1);  // A0 A1 | ...
    473   const __m128i A23 = _mm_unpacklo_epi16(src2, src3);  // A2 A3 | ...
    474   const __m128i B0 = _mm_adds_epi16(A01, A23);    // a0 | a1 | ...
    475   const __m128i B1 = _mm_subs_epi16(A01, A23);    // a3 | a2 | ...
    476   const __m128i C0 = _mm_unpacklo_epi32(B0, B1);  // a0 | a1 | a3 | a2
    477   const __m128i C1 = _mm_unpacklo_epi32(B1, B0);  // a3 | a2 | a0 | a1
    478   const __m128i D0 = _mm_madd_epi16(C0, kMult1);  // out0, out1
    479   const __m128i D1 = _mm_madd_epi16(C1, kMult2);  // out2, out3
    480   *out = _mm_unpacklo_epi64(D0, D1);
    481 }
    482 
    483 static void FTransformWHT(const int16_t* in, int16_t* out) {
    484   __m128i row0, row1, row2, row3;
    485   FTransformWHTRow(in + 0 * 64, &row0);
    486   FTransformWHTRow(in + 1 * 64, &row1);
    487   FTransformWHTRow(in + 2 * 64, &row2);
    488   FTransformWHTRow(in + 3 * 64, &row3);
    489 
    490   {
    491     const __m128i a0 = _mm_add_epi32(row0, row2);
    492     const __m128i a1 = _mm_add_epi32(row1, row3);
    493     const __m128i a2 = _mm_sub_epi32(row1, row3);
    494     const __m128i a3 = _mm_sub_epi32(row0, row2);
    495     const __m128i b0 = _mm_srai_epi32(_mm_add_epi32(a0, a1), 1);
    496     const __m128i b1 = _mm_srai_epi32(_mm_add_epi32(a3, a2), 1);
    497     const __m128i b2 = _mm_srai_epi32(_mm_sub_epi32(a3, a2), 1);
    498     const __m128i b3 = _mm_srai_epi32(_mm_sub_epi32(a0, a1), 1);
    499     const __m128i out0 = _mm_packs_epi32(b0, b1);
    500     const __m128i out1 = _mm_packs_epi32(b2, b3);
    501     _mm_storeu_si128((__m128i*)&out[0], out0);
    502     _mm_storeu_si128((__m128i*)&out[8], out1);
    503   }
    504 }
    505 
    506 //------------------------------------------------------------------------------
    507 // Compute susceptibility based on DCT-coeff histograms:
    508 // the higher, the "easier" the macroblock is to compress.
    509 
    510 static void CollectHistogram(const uint8_t* ref, const uint8_t* pred,
    511                              int start_block, int end_block,
    512                              VP8Histogram* const histo) {
    513   const __m128i zero = _mm_setzero_si128();
    514   const __m128i max_coeff_thresh = _mm_set1_epi16(MAX_COEFF_THRESH);
    515   int j;
    516   int distribution[MAX_COEFF_THRESH + 1] = { 0 };
    517   for (j = start_block; j < end_block; ++j) {
    518     int16_t out[16];
    519     int k;
    520 
    521     FTransform(ref + VP8DspScan[j], pred + VP8DspScan[j], out);
    522 
    523     // Convert coefficients to bin (within out[]).
    524     {
    525       // Load.
    526       const __m128i out0 = _mm_loadu_si128((__m128i*)&out[0]);
    527       const __m128i out1 = _mm_loadu_si128((__m128i*)&out[8]);
    528       const __m128i d0 = _mm_sub_epi16(zero, out0);
    529       const __m128i d1 = _mm_sub_epi16(zero, out1);
    530       const __m128i abs0 = _mm_max_epi16(out0, d0);   // abs(v), 16b
    531       const __m128i abs1 = _mm_max_epi16(out1, d1);
    532       // v = abs(out) >> 3
    533       const __m128i v0 = _mm_srai_epi16(abs0, 3);
    534       const __m128i v1 = _mm_srai_epi16(abs1, 3);
    535       // bin = min(v, MAX_COEFF_THRESH)
    536       const __m128i bin0 = _mm_min_epi16(v0, max_coeff_thresh);
    537       const __m128i bin1 = _mm_min_epi16(v1, max_coeff_thresh);
    538       // Store.
    539       _mm_storeu_si128((__m128i*)&out[0], bin0);
    540       _mm_storeu_si128((__m128i*)&out[8], bin1);
    541     }
    542 
    543     // Convert coefficients to bin.
    544     for (k = 0; k < 16; ++k) {
    545       ++distribution[out[k]];
    546     }
    547   }
    548   VP8SetHistogramData(distribution, histo);
    549 }
    550 
    551 //------------------------------------------------------------------------------
    552 // Intra predictions
    553 
    554 // helper for chroma-DC predictions
    555 static WEBP_INLINE void Put8x8uv(uint8_t v, uint8_t* dst) {
    556   int j;
    557   const __m128i values = _mm_set1_epi8(v);
    558   for (j = 0; j < 8; ++j) {
    559     _mm_storel_epi64((__m128i*)(dst + j * BPS), values);
    560   }
    561 }
    562 
    563 static WEBP_INLINE void Put16(uint8_t v, uint8_t* dst) {
    564   int j;
    565   const __m128i values = _mm_set1_epi8(v);
    566   for (j = 0; j < 16; ++j) {
    567     _mm_store_si128((__m128i*)(dst + j * BPS), values);
    568   }
    569 }
    570 
    571 static WEBP_INLINE void Fill(uint8_t* dst, int value, int size) {
    572   if (size == 4) {
    573     int j;
    574     for (j = 0; j < 4; ++j) {
    575       memset(dst + j * BPS, value, 4);
    576     }
    577   } else if (size == 8) {
    578     Put8x8uv(value, dst);
    579   } else {
    580     Put16(value, dst);
    581   }
    582 }
    583 
    584 static WEBP_INLINE void VE8uv(uint8_t* dst, const uint8_t* top) {
    585   int j;
    586   const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);
    587   for (j = 0; j < 8; ++j) {
    588     _mm_storel_epi64((__m128i*)(dst + j * BPS), top_values);
    589   }
    590 }
    591 
    592 static WEBP_INLINE void VE16(uint8_t* dst, const uint8_t* top) {
    593   const __m128i top_values = _mm_load_si128((const __m128i*)top);
    594   int j;
    595   for (j = 0; j < 16; ++j) {
    596     _mm_store_si128((__m128i*)(dst + j * BPS), top_values);
    597   }
    598 }
    599 
    600 static WEBP_INLINE void VerticalPred(uint8_t* dst,
    601                                      const uint8_t* top, int size) {
    602   if (top != NULL) {
    603     if (size == 8) {
    604       VE8uv(dst, top);
    605     } else {
    606       VE16(dst, top);
    607     }
    608   } else {
    609     Fill(dst, 127, size);
    610   }
    611 }
    612 
    613 static WEBP_INLINE void HE8uv(uint8_t* dst, const uint8_t* left) {
    614   int j;
    615   for (j = 0; j < 8; ++j) {
    616     const __m128i values = _mm_set1_epi8(left[j]);
    617     _mm_storel_epi64((__m128i*)dst, values);
    618     dst += BPS;
    619   }
    620 }
    621 
    622 static WEBP_INLINE void HE16(uint8_t* dst, const uint8_t* left) {
    623   int j;
    624   for (j = 0; j < 16; ++j) {
    625     const __m128i values = _mm_set1_epi8(left[j]);
    626     _mm_store_si128((__m128i*)dst, values);
    627     dst += BPS;
    628   }
    629 }
    630 
    631 static WEBP_INLINE void HorizontalPred(uint8_t* dst,
    632                                        const uint8_t* left, int size) {
    633   if (left != NULL) {
    634     if (size == 8) {
    635       HE8uv(dst, left);
    636     } else {
    637       HE16(dst, left);
    638     }
    639   } else {
    640     Fill(dst, 129, size);
    641   }
    642 }
    643 
    644 static WEBP_INLINE void TM(uint8_t* dst, const uint8_t* left,
    645                            const uint8_t* top, int size) {
    646   const __m128i zero = _mm_setzero_si128();
    647   int y;
    648   if (size == 8) {
    649     const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);
    650     const __m128i top_base = _mm_unpacklo_epi8(top_values, zero);
    651     for (y = 0; y < 8; ++y, dst += BPS) {
    652       const int val = left[y] - left[-1];
    653       const __m128i base = _mm_set1_epi16(val);
    654       const __m128i out = _mm_packus_epi16(_mm_add_epi16(base, top_base), zero);
    655       _mm_storel_epi64((__m128i*)dst, out);
    656     }
    657   } else {
    658     const __m128i top_values = _mm_load_si128((const __m128i*)top);
    659     const __m128i top_base_0 = _mm_unpacklo_epi8(top_values, zero);
    660     const __m128i top_base_1 = _mm_unpackhi_epi8(top_values, zero);
    661     for (y = 0; y < 16; ++y, dst += BPS) {
    662       const int val = left[y] - left[-1];
    663       const __m128i base = _mm_set1_epi16(val);
    664       const __m128i out_0 = _mm_add_epi16(base, top_base_0);
    665       const __m128i out_1 = _mm_add_epi16(base, top_base_1);
    666       const __m128i out = _mm_packus_epi16(out_0, out_1);
    667       _mm_store_si128((__m128i*)dst, out);
    668     }
    669   }
    670 }
    671 
    672 static WEBP_INLINE void TrueMotion(uint8_t* dst, const uint8_t* left,
    673                                    const uint8_t* top, int size) {
    674   if (left != NULL) {
    675     if (top != NULL) {
    676       TM(dst, left, top, size);
    677     } else {
    678       HorizontalPred(dst, left, size);
    679     }
    680   } else {
    681     // true motion without left samples (hence: with default 129 value)
    682     // is equivalent to VE prediction where you just copy the top samples.
    683     // Note that if top samples are not available, the default value is
    684     // then 129, and not 127 as in the VerticalPred case.
    685     if (top != NULL) {
    686       VerticalPred(dst, top, size);
    687     } else {
    688       Fill(dst, 129, size);
    689     }
    690   }
    691 }
    692 
    693 static WEBP_INLINE void DC8uv(uint8_t* dst, const uint8_t* left,
    694                               const uint8_t* top) {
    695   const __m128i zero = _mm_setzero_si128();
    696   const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);
    697   const __m128i left_values = _mm_loadl_epi64((const __m128i*)left);
    698   const __m128i sum_top = _mm_sad_epu8(top_values, zero);
    699   const __m128i sum_left = _mm_sad_epu8(left_values, zero);
    700   const int DC = _mm_cvtsi128_si32(sum_top) + _mm_cvtsi128_si32(sum_left) + 8;
    701   Put8x8uv(DC >> 4, dst);
    702 }
    703 
    704 static WEBP_INLINE void DC8uvNoLeft(uint8_t* dst, const uint8_t* top) {
    705   const __m128i zero = _mm_setzero_si128();
    706   const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);
    707   const __m128i sum = _mm_sad_epu8(top_values, zero);
    708   const int DC = _mm_cvtsi128_si32(sum) + 4;
    709   Put8x8uv(DC >> 3, dst);
    710 }
    711 
    712 static WEBP_INLINE void DC8uvNoTop(uint8_t* dst, const uint8_t* left) {
    713   // 'left' is contiguous so we can reuse the top summation.
    714   DC8uvNoLeft(dst, left);
    715 }
    716 
    717 static WEBP_INLINE void DC8uvNoTopLeft(uint8_t* dst) {
    718   Put8x8uv(0x80, dst);
    719 }
    720 
    721 static WEBP_INLINE void DC8uvMode(uint8_t* dst, const uint8_t* left,
    722                                   const uint8_t* top) {
    723   if (top != NULL) {
    724     if (left != NULL) {  // top and left present
    725       DC8uv(dst, left, top);
    726     } else {  // top, but no left
    727       DC8uvNoLeft(dst, top);
    728     }
    729   } else if (left != NULL) {  // left but no top
    730     DC8uvNoTop(dst, left);
    731   } else {  // no top, no left, nothing.
    732     DC8uvNoTopLeft(dst);
    733   }
    734 }
    735 
    736 static WEBP_INLINE void DC16(uint8_t* dst, const uint8_t* left,
    737                              const uint8_t* top) {
    738   const __m128i zero = _mm_setzero_si128();
    739   const __m128i top_row = _mm_load_si128((const __m128i*)top);
    740   const __m128i left_row = _mm_load_si128((const __m128i*)left);
    741   const __m128i sad8x2 = _mm_sad_epu8(top_row, zero);
    742   // sum the two sads: sad8x2[0:1] + sad8x2[8:9]
    743   const __m128i sum_top = _mm_add_epi16(sad8x2, _mm_shuffle_epi32(sad8x2, 2));
    744   const __m128i sad8x2_left = _mm_sad_epu8(left_row, zero);
    745   // sum the two sads: sad8x2[0:1] + sad8x2[8:9]
    746   const __m128i sum_left =
    747       _mm_add_epi16(sad8x2_left, _mm_shuffle_epi32(sad8x2_left, 2));
    748   const int DC = _mm_cvtsi128_si32(sum_top) + _mm_cvtsi128_si32(sum_left) + 16;
    749   Put16(DC >> 5, dst);
    750 }
    751 
    752 static WEBP_INLINE void DC16NoLeft(uint8_t* dst, const uint8_t* top) {
    753   const __m128i zero = _mm_setzero_si128();
    754   const __m128i top_row = _mm_load_si128((const __m128i*)top);
    755   const __m128i sad8x2 = _mm_sad_epu8(top_row, zero);
    756   // sum the two sads: sad8x2[0:1] + sad8x2[8:9]
    757   const __m128i sum = _mm_add_epi16(sad8x2, _mm_shuffle_epi32(sad8x2, 2));
    758   const int DC = _mm_cvtsi128_si32(sum) + 8;
    759   Put16(DC >> 4, dst);
    760 }
    761 
    762 static WEBP_INLINE void DC16NoTop(uint8_t* dst, const uint8_t* left) {
    763   // 'left' is contiguous so we can reuse the top summation.
    764   DC16NoLeft(dst, left);
    765 }
    766 
    767 static WEBP_INLINE void DC16NoTopLeft(uint8_t* dst) {
    768   Put16(0x80, dst);
    769 }
    770 
    771 static WEBP_INLINE void DC16Mode(uint8_t* dst, const uint8_t* left,
    772                                  const uint8_t* top) {
    773   if (top != NULL) {
    774     if (left != NULL) {  // top and left present
    775       DC16(dst, left, top);
    776     } else {  // top, but no left
    777       DC16NoLeft(dst, top);
    778     }
    779   } else if (left != NULL) {  // left but no top
    780     DC16NoTop(dst, left);
    781   } else {  // no top, no left, nothing.
    782     DC16NoTopLeft(dst);
    783   }
    784 }
    785 
    786 //------------------------------------------------------------------------------
    787 // 4x4 predictions
    788 
    789 #define DST(x, y) dst[(x) + (y) * BPS]
    790 #define AVG3(a, b, c) (((a) + 2 * (b) + (c) + 2) >> 2)
    791 #define AVG2(a, b) (((a) + (b) + 1) >> 1)
    792 
    793 // We use the following 8b-arithmetic tricks:
    794 //     (a + 2 * b + c + 2) >> 2 = (AC + b + 1) >> 1
    795 //   where: AC = (a + c) >> 1 = [(a + c + 1) >> 1] - [(a^c) & 1]
    796 // and:
    797 //     (a + 2 * b + c + 2) >> 2 = (AB + BC + 1) >> 1 - (ab|bc)&lsb
    798 //   where: AC = (a + b + 1) >> 1,   BC = (b + c + 1) >> 1
    799 //   and ab = a ^ b, bc = b ^ c, lsb = (AC^BC)&1
    800 
    801 static WEBP_INLINE void VE4(uint8_t* dst, const uint8_t* top) {  // vertical
    802   const __m128i one = _mm_set1_epi8(1);
    803   const __m128i ABCDEFGH = _mm_loadl_epi64((__m128i*)(top - 1));
    804   const __m128i BCDEFGH0 = _mm_srli_si128(ABCDEFGH, 1);
    805   const __m128i CDEFGH00 = _mm_srli_si128(ABCDEFGH, 2);
    806   const __m128i a = _mm_avg_epu8(ABCDEFGH, CDEFGH00);
    807   const __m128i lsb = _mm_and_si128(_mm_xor_si128(ABCDEFGH, CDEFGH00), one);
    808   const __m128i b = _mm_subs_epu8(a, lsb);
    809   const __m128i avg = _mm_avg_epu8(b, BCDEFGH0);
    810   const uint32_t vals = _mm_cvtsi128_si32(avg);
    811   int i;
    812   for (i = 0; i < 4; ++i) {
    813     WebPUint32ToMem(dst + i * BPS, vals);
    814   }
    815 }
    816 
    817 static WEBP_INLINE void HE4(uint8_t* dst, const uint8_t* top) {  // horizontal
    818   const int X = top[-1];
    819   const int I = top[-2];
    820   const int J = top[-3];
    821   const int K = top[-4];
    822   const int L = top[-5];
    823   WebPUint32ToMem(dst + 0 * BPS, 0x01010101U * AVG3(X, I, J));
    824   WebPUint32ToMem(dst + 1 * BPS, 0x01010101U * AVG3(I, J, K));
    825   WebPUint32ToMem(dst + 2 * BPS, 0x01010101U * AVG3(J, K, L));
    826   WebPUint32ToMem(dst + 3 * BPS, 0x01010101U * AVG3(K, L, L));
    827 }
    828 
    829 static WEBP_INLINE void DC4(uint8_t* dst, const uint8_t* top) {
    830   uint32_t dc = 4;
    831   int i;
    832   for (i = 0; i < 4; ++i) dc += top[i] + top[-5 + i];
    833   Fill(dst, dc >> 3, 4);
    834 }
    835 
    836 static WEBP_INLINE void LD4(uint8_t* dst, const uint8_t* top) {  // Down-Left
    837   const __m128i one = _mm_set1_epi8(1);
    838   const __m128i ABCDEFGH = _mm_loadl_epi64((const __m128i*)top);
    839   const __m128i BCDEFGH0 = _mm_srli_si128(ABCDEFGH, 1);
    840   const __m128i CDEFGH00 = _mm_srli_si128(ABCDEFGH, 2);
    841   const __m128i CDEFGHH0 = _mm_insert_epi16(CDEFGH00, top[7], 3);
    842   const __m128i avg1 = _mm_avg_epu8(ABCDEFGH, CDEFGHH0);
    843   const __m128i lsb = _mm_and_si128(_mm_xor_si128(ABCDEFGH, CDEFGHH0), one);
    844   const __m128i avg2 = _mm_subs_epu8(avg1, lsb);
    845   const __m128i abcdefg = _mm_avg_epu8(avg2, BCDEFGH0);
    846   WebPUint32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(               abcdefg    ));
    847   WebPUint32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 1)));
    848   WebPUint32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 2)));
    849   WebPUint32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 3)));
    850 }
    851 
    852 static WEBP_INLINE void VR4(uint8_t* dst,
    853                             const uint8_t* top) {  // Vertical-Right
    854   const __m128i one = _mm_set1_epi8(1);
    855   const int I = top[-2];
    856   const int J = top[-3];
    857   const int K = top[-4];
    858   const int X = top[-1];
    859   const __m128i XABCD = _mm_loadl_epi64((const __m128i*)(top - 1));
    860   const __m128i ABCD0 = _mm_srli_si128(XABCD, 1);
    861   const __m128i abcd = _mm_avg_epu8(XABCD, ABCD0);
    862   const __m128i _XABCD = _mm_slli_si128(XABCD, 1);
    863   const __m128i IXABCD = _mm_insert_epi16(_XABCD, I | (X << 8), 0);
    864   const __m128i avg1 = _mm_avg_epu8(IXABCD, ABCD0);
    865   const __m128i lsb = _mm_and_si128(_mm_xor_si128(IXABCD, ABCD0), one);
    866   const __m128i avg2 = _mm_subs_epu8(avg1, lsb);
    867   const __m128i efgh = _mm_avg_epu8(avg2, XABCD);
    868   WebPUint32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(               abcd    ));
    869   WebPUint32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(               efgh    ));
    870   WebPUint32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_slli_si128(abcd, 1)));
    871   WebPUint32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(_mm_slli_si128(efgh, 1)));
    872 
    873   // these two are hard to implement in SSE2, so we keep the C-version:
    874   DST(0, 2) = AVG3(J, I, X);
    875   DST(0, 3) = AVG3(K, J, I);
    876 }
    877 
    878 static WEBP_INLINE void VL4(uint8_t* dst,
    879                             const uint8_t* top) {  // Vertical-Left
    880   const __m128i one = _mm_set1_epi8(1);
    881   const __m128i ABCDEFGH = _mm_loadl_epi64((const __m128i*)top);
    882   const __m128i BCDEFGH_ = _mm_srli_si128(ABCDEFGH, 1);
    883   const __m128i CDEFGH__ = _mm_srli_si128(ABCDEFGH, 2);
    884   const __m128i avg1 = _mm_avg_epu8(ABCDEFGH, BCDEFGH_);
    885   const __m128i avg2 = _mm_avg_epu8(CDEFGH__, BCDEFGH_);
    886   const __m128i avg3 = _mm_avg_epu8(avg1, avg2);
    887   const __m128i lsb1 = _mm_and_si128(_mm_xor_si128(avg1, avg2), one);
    888   const __m128i ab = _mm_xor_si128(ABCDEFGH, BCDEFGH_);
    889   const __m128i bc = _mm_xor_si128(CDEFGH__, BCDEFGH_);
    890   const __m128i abbc = _mm_or_si128(ab, bc);
    891   const __m128i lsb2 = _mm_and_si128(abbc, lsb1);
    892   const __m128i avg4 = _mm_subs_epu8(avg3, lsb2);
    893   const uint32_t extra_out = _mm_cvtsi128_si32(_mm_srli_si128(avg4, 4));
    894   WebPUint32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(               avg1    ));
    895   WebPUint32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(               avg4    ));
    896   WebPUint32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(avg1, 1)));
    897   WebPUint32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(avg4, 1)));
    898 
    899   // these two are hard to get and irregular
    900   DST(3, 2) = (extra_out >> 0) & 0xff;
    901   DST(3, 3) = (extra_out >> 8) & 0xff;
    902 }
    903 
    904 static WEBP_INLINE void RD4(uint8_t* dst, const uint8_t* top) {  // Down-right
    905   const __m128i one = _mm_set1_epi8(1);
    906   const __m128i LKJIXABC = _mm_loadl_epi64((const __m128i*)(top - 5));
    907   const __m128i LKJIXABCD = _mm_insert_epi16(LKJIXABC, top[3], 4);
    908   const __m128i KJIXABCD_ = _mm_srli_si128(LKJIXABCD, 1);
    909   const __m128i JIXABCD__ = _mm_srli_si128(LKJIXABCD, 2);
    910   const __m128i avg1 = _mm_avg_epu8(JIXABCD__, LKJIXABCD);
    911   const __m128i lsb = _mm_and_si128(_mm_xor_si128(JIXABCD__, LKJIXABCD), one);
    912   const __m128i avg2 = _mm_subs_epu8(avg1, lsb);
    913   const __m128i abcdefg = _mm_avg_epu8(avg2, KJIXABCD_);
    914   WebPUint32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(               abcdefg    ));
    915   WebPUint32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 1)));
    916   WebPUint32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 2)));
    917   WebPUint32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 3)));
    918 }
    919 
    920 static WEBP_INLINE void HU4(uint8_t* dst, const uint8_t* top) {
    921   const int I = top[-2];
    922   const int J = top[-3];
    923   const int K = top[-4];
    924   const int L = top[-5];
    925   DST(0, 0) =             AVG2(I, J);
    926   DST(2, 0) = DST(0, 1) = AVG2(J, K);
    927   DST(2, 1) = DST(0, 2) = AVG2(K, L);
    928   DST(1, 0) =             AVG3(I, J, K);
    929   DST(3, 0) = DST(1, 1) = AVG3(J, K, L);
    930   DST(3, 1) = DST(1, 2) = AVG3(K, L, L);
    931   DST(3, 2) = DST(2, 2) =
    932   DST(0, 3) = DST(1, 3) = DST(2, 3) = DST(3, 3) = L;
    933 }
    934 
    935 static WEBP_INLINE void HD4(uint8_t* dst, const uint8_t* top) {
    936   const int X = top[-1];
    937   const int I = top[-2];
    938   const int J = top[-3];
    939   const int K = top[-4];
    940   const int L = top[-5];
    941   const int A = top[0];
    942   const int B = top[1];
    943   const int C = top[2];
    944 
    945   DST(0, 0) = DST(2, 1) = AVG2(I, X);
    946   DST(0, 1) = DST(2, 2) = AVG2(J, I);
    947   DST(0, 2) = DST(2, 3) = AVG2(K, J);
    948   DST(0, 3)             = AVG2(L, K);
    949 
    950   DST(3, 0)             = AVG3(A, B, C);
    951   DST(2, 0)             = AVG3(X, A, B);
    952   DST(1, 0) = DST(3, 1) = AVG3(I, X, A);
    953   DST(1, 1) = DST(3, 2) = AVG3(J, I, X);
    954   DST(1, 2) = DST(3, 3) = AVG3(K, J, I);
    955   DST(1, 3)             = AVG3(L, K, J);
    956 }
    957 
    958 static WEBP_INLINE void TM4(uint8_t* dst, const uint8_t* top) {
    959   const __m128i zero = _mm_setzero_si128();
    960   const __m128i top_values = _mm_cvtsi32_si128(WebPMemToUint32(top));
    961   const __m128i top_base = _mm_unpacklo_epi8(top_values, zero);
    962   int y;
    963   for (y = 0; y < 4; ++y, dst += BPS) {
    964     const int val = top[-2 - y] - top[-1];
    965     const __m128i base = _mm_set1_epi16(val);
    966     const __m128i out = _mm_packus_epi16(_mm_add_epi16(base, top_base), zero);
    967     WebPUint32ToMem(dst, _mm_cvtsi128_si32(out));
    968   }
    969 }
    970 
    971 #undef DST
    972 #undef AVG3
    973 #undef AVG2
    974 
    975 //------------------------------------------------------------------------------
    976 // luma 4x4 prediction
    977 
    978 // Left samples are top[-5 .. -2], top_left is top[-1], top are
    979 // located at top[0..3], and top right is top[4..7]
    980 static void Intra4Preds(uint8_t* dst, const uint8_t* top) {
    981   DC4(I4DC4 + dst, top);
    982   TM4(I4TM4 + dst, top);
    983   VE4(I4VE4 + dst, top);
    984   HE4(I4HE4 + dst, top);
    985   RD4(I4RD4 + dst, top);
    986   VR4(I4VR4 + dst, top);
    987   LD4(I4LD4 + dst, top);
    988   VL4(I4VL4 + dst, top);
    989   HD4(I4HD4 + dst, top);
    990   HU4(I4HU4 + dst, top);
    991 }
    992 
    993 //------------------------------------------------------------------------------
    994 // Chroma 8x8 prediction (paragraph 12.2)
    995 
    996 static void IntraChromaPreds(uint8_t* dst, const uint8_t* left,
    997                              const uint8_t* top) {
    998   // U block
    999   DC8uvMode(C8DC8 + dst, left, top);
   1000   VerticalPred(C8VE8 + dst, top, 8);
   1001   HorizontalPred(C8HE8 + dst, left, 8);
   1002   TrueMotion(C8TM8 + dst, left, top, 8);
   1003   // V block
   1004   dst += 8;
   1005   if (top != NULL) top += 8;
   1006   if (left != NULL) left += 16;
   1007   DC8uvMode(C8DC8 + dst, left, top);
   1008   VerticalPred(C8VE8 + dst, top, 8);
   1009   HorizontalPred(C8HE8 + dst, left, 8);
   1010   TrueMotion(C8TM8 + dst, left, top, 8);
   1011 }
   1012 
   1013 //------------------------------------------------------------------------------
   1014 // luma 16x16 prediction (paragraph 12.3)
   1015 
   1016 static void Intra16Preds(uint8_t* dst,
   1017                          const uint8_t* left, const uint8_t* top) {
   1018   DC16Mode(I16DC16 + dst, left, top);
   1019   VerticalPred(I16VE16 + dst, top, 16);
   1020   HorizontalPred(I16HE16 + dst, left, 16);
   1021   TrueMotion(I16TM16 + dst, left, top, 16);
   1022 }
   1023 
   1024 //------------------------------------------------------------------------------
   1025 // Metric
   1026 
   1027 static WEBP_INLINE void SubtractAndAccumulate(const __m128i a, const __m128i b,
   1028                                               __m128i* const sum) {
   1029   // take abs(a-b) in 8b
   1030   const __m128i a_b = _mm_subs_epu8(a, b);
   1031   const __m128i b_a = _mm_subs_epu8(b, a);
   1032   const __m128i abs_a_b = _mm_or_si128(a_b, b_a);
   1033   // zero-extend to 16b
   1034   const __m128i zero = _mm_setzero_si128();
   1035   const __m128i C0 = _mm_unpacklo_epi8(abs_a_b, zero);
   1036   const __m128i C1 = _mm_unpackhi_epi8(abs_a_b, zero);
   1037   // multiply with self
   1038   const __m128i sum1 = _mm_madd_epi16(C0, C0);
   1039   const __m128i sum2 = _mm_madd_epi16(C1, C1);
   1040   *sum = _mm_add_epi32(sum1, sum2);
   1041 }
   1042 
   1043 static WEBP_INLINE int SSE_16xN(const uint8_t* a, const uint8_t* b,
   1044                                 int num_pairs) {
   1045   __m128i sum = _mm_setzero_si128();
   1046   int32_t tmp[4];
   1047   int i;
   1048 
   1049   for (i = 0; i < num_pairs; ++i) {
   1050     const __m128i a0 = _mm_loadu_si128((const __m128i*)&a[BPS * 0]);
   1051     const __m128i b0 = _mm_loadu_si128((const __m128i*)&b[BPS * 0]);
   1052     const __m128i a1 = _mm_loadu_si128((const __m128i*)&a[BPS * 1]);
   1053     const __m128i b1 = _mm_loadu_si128((const __m128i*)&b[BPS * 1]);
   1054     __m128i sum1, sum2;
   1055     SubtractAndAccumulate(a0, b0, &sum1);
   1056     SubtractAndAccumulate(a1, b1, &sum2);
   1057     sum = _mm_add_epi32(sum, _mm_add_epi32(sum1, sum2));
   1058     a += 2 * BPS;
   1059     b += 2 * BPS;
   1060   }
   1061   _mm_storeu_si128((__m128i*)tmp, sum);
   1062   return (tmp[3] + tmp[2] + tmp[1] + tmp[0]);
   1063 }
   1064 
   1065 static int SSE16x16(const uint8_t* a, const uint8_t* b) {
   1066   return SSE_16xN(a, b, 8);
   1067 }
   1068 
   1069 static int SSE16x8(const uint8_t* a, const uint8_t* b) {
   1070   return SSE_16xN(a, b, 4);
   1071 }
   1072 
   1073 #define LOAD_8x16b(ptr) \
   1074   _mm_unpacklo_epi8(_mm_loadl_epi64((const __m128i*)(ptr)), zero)
   1075 
   1076 static int SSE8x8(const uint8_t* a, const uint8_t* b) {
   1077   const __m128i zero = _mm_setzero_si128();
   1078   int num_pairs = 4;
   1079   __m128i sum = zero;
   1080   int32_t tmp[4];
   1081   while (num_pairs-- > 0) {
   1082     const __m128i a0 = LOAD_8x16b(&a[BPS * 0]);
   1083     const __m128i a1 = LOAD_8x16b(&a[BPS * 1]);
   1084     const __m128i b0 = LOAD_8x16b(&b[BPS * 0]);
   1085     const __m128i b1 = LOAD_8x16b(&b[BPS * 1]);
   1086     // subtract
   1087     const __m128i c0 = _mm_subs_epi16(a0, b0);
   1088     const __m128i c1 = _mm_subs_epi16(a1, b1);
   1089     // multiply/accumulate with self
   1090     const __m128i d0 = _mm_madd_epi16(c0, c0);
   1091     const __m128i d1 = _mm_madd_epi16(c1, c1);
   1092     // collect
   1093     const __m128i sum01 = _mm_add_epi32(d0, d1);
   1094     sum = _mm_add_epi32(sum, sum01);
   1095     a += 2 * BPS;
   1096     b += 2 * BPS;
   1097   }
   1098   _mm_storeu_si128((__m128i*)tmp, sum);
   1099   return (tmp[3] + tmp[2] + tmp[1] + tmp[0]);
   1100 }
   1101 #undef LOAD_8x16b
   1102 
   1103 static int SSE4x4(const uint8_t* a, const uint8_t* b) {
   1104   const __m128i zero = _mm_setzero_si128();
   1105 
   1106   // Load values. Note that we read 8 pixels instead of 4,
   1107   // but the a/b buffers are over-allocated to that effect.
   1108   const __m128i a0 = _mm_loadl_epi64((const __m128i*)&a[BPS * 0]);
   1109   const __m128i a1 = _mm_loadl_epi64((const __m128i*)&a[BPS * 1]);
   1110   const __m128i a2 = _mm_loadl_epi64((const __m128i*)&a[BPS * 2]);
   1111   const __m128i a3 = _mm_loadl_epi64((const __m128i*)&a[BPS * 3]);
   1112   const __m128i b0 = _mm_loadl_epi64((const __m128i*)&b[BPS * 0]);
   1113   const __m128i b1 = _mm_loadl_epi64((const __m128i*)&b[BPS * 1]);
   1114   const __m128i b2 = _mm_loadl_epi64((const __m128i*)&b[BPS * 2]);
   1115   const __m128i b3 = _mm_loadl_epi64((const __m128i*)&b[BPS * 3]);
   1116   // Combine pair of lines.
   1117   const __m128i a01 = _mm_unpacklo_epi32(a0, a1);
   1118   const __m128i a23 = _mm_unpacklo_epi32(a2, a3);
   1119   const __m128i b01 = _mm_unpacklo_epi32(b0, b1);
   1120   const __m128i b23 = _mm_unpacklo_epi32(b2, b3);
   1121   // Convert to 16b.
   1122   const __m128i a01s = _mm_unpacklo_epi8(a01, zero);
   1123   const __m128i a23s = _mm_unpacklo_epi8(a23, zero);
   1124   const __m128i b01s = _mm_unpacklo_epi8(b01, zero);
   1125   const __m128i b23s = _mm_unpacklo_epi8(b23, zero);
   1126   // subtract, square and accumulate
   1127   const __m128i d0 = _mm_subs_epi16(a01s, b01s);
   1128   const __m128i d1 = _mm_subs_epi16(a23s, b23s);
   1129   const __m128i e0 = _mm_madd_epi16(d0, d0);
   1130   const __m128i e1 = _mm_madd_epi16(d1, d1);
   1131   const __m128i sum = _mm_add_epi32(e0, e1);
   1132 
   1133   int32_t tmp[4];
   1134   _mm_storeu_si128((__m128i*)tmp, sum);
   1135   return (tmp[3] + tmp[2] + tmp[1] + tmp[0]);
   1136 }
   1137 
   1138 //------------------------------------------------------------------------------
   1139 // Texture distortion
   1140 //
   1141 // We try to match the spectral content (weighted) between source and
   1142 // reconstructed samples.
   1143 
   1144 // Hadamard transform
   1145 // Returns the difference between the weighted sum of the absolute value of
   1146 // transformed coefficients.
   1147 static int TTransform(const uint8_t* inA, const uint8_t* inB,
   1148                       const uint16_t* const w) {
   1149   int32_t sum[4];
   1150   __m128i tmp_0, tmp_1, tmp_2, tmp_3;
   1151   const __m128i zero = _mm_setzero_si128();
   1152 
   1153   // Load, combine and transpose inputs.
   1154   {
   1155     const __m128i inA_0 = _mm_loadl_epi64((const __m128i*)&inA[BPS * 0]);
   1156     const __m128i inA_1 = _mm_loadl_epi64((const __m128i*)&inA[BPS * 1]);
   1157     const __m128i inA_2 = _mm_loadl_epi64((const __m128i*)&inA[BPS * 2]);
   1158     const __m128i inA_3 = _mm_loadl_epi64((const __m128i*)&inA[BPS * 3]);
   1159     const __m128i inB_0 = _mm_loadl_epi64((const __m128i*)&inB[BPS * 0]);
   1160     const __m128i inB_1 = _mm_loadl_epi64((const __m128i*)&inB[BPS * 1]);
   1161     const __m128i inB_2 = _mm_loadl_epi64((const __m128i*)&inB[BPS * 2]);
   1162     const __m128i inB_3 = _mm_loadl_epi64((const __m128i*)&inB[BPS * 3]);
   1163 
   1164     // Combine inA and inB (we'll do two transforms in parallel).
   1165     const __m128i inAB_0 = _mm_unpacklo_epi8(inA_0, inB_0);
   1166     const __m128i inAB_1 = _mm_unpacklo_epi8(inA_1, inB_1);
   1167     const __m128i inAB_2 = _mm_unpacklo_epi8(inA_2, inB_2);
   1168     const __m128i inAB_3 = _mm_unpacklo_epi8(inA_3, inB_3);
   1169     // a00 b00 a01 b01 a02 b03 a03 b03   0 0 0 0 0 0 0 0
   1170     // a10 b10 a11 b11 a12 b12 a13 b13   0 0 0 0 0 0 0 0
   1171     // a20 b20 a21 b21 a22 b22 a23 b23   0 0 0 0 0 0 0 0
   1172     // a30 b30 a31 b31 a32 b32 a33 b33   0 0 0 0 0 0 0 0
   1173 
   1174     // Transpose the two 4x4, discarding the filling zeroes.
   1175     const __m128i transpose0_0 = _mm_unpacklo_epi8(inAB_0, inAB_2);
   1176     const __m128i transpose0_1 = _mm_unpacklo_epi8(inAB_1, inAB_3);
   1177     // a00 a20  b00 b20  a01 a21  b01 b21  a02 a22  b02 b22  a03 a23  b03 b23
   1178     // a10 a30  b10 b30  a11 a31  b11 b31  a12 a32  b12 b32  a13 a33  b13 b33
   1179     const __m128i transpose1_0 = _mm_unpacklo_epi8(transpose0_0, transpose0_1);
   1180     const __m128i transpose1_1 = _mm_unpackhi_epi8(transpose0_0, transpose0_1);
   1181     // a00 a10 a20 a30  b00 b10 b20 b30  a01 a11 a21 a31  b01 b11 b21 b31
   1182     // a02 a12 a22 a32  b02 b12 b22 b32  a03 a13 a23 a33  b03 b13 b23 b33
   1183 
   1184     // Convert to 16b.
   1185     tmp_0 = _mm_unpacklo_epi8(transpose1_0, zero);
   1186     tmp_1 = _mm_unpackhi_epi8(transpose1_0, zero);
   1187     tmp_2 = _mm_unpacklo_epi8(transpose1_1, zero);
   1188     tmp_3 = _mm_unpackhi_epi8(transpose1_1, zero);
   1189     // a00 a10 a20 a30   b00 b10 b20 b30
   1190     // a01 a11 a21 a31   b01 b11 b21 b31
   1191     // a02 a12 a22 a32   b02 b12 b22 b32
   1192     // a03 a13 a23 a33   b03 b13 b23 b33
   1193   }
   1194 
   1195   // Horizontal pass and subsequent transpose.
   1196   {
   1197     // Calculate a and b (two 4x4 at once).
   1198     const __m128i a0 = _mm_add_epi16(tmp_0, tmp_2);
   1199     const __m128i a1 = _mm_add_epi16(tmp_1, tmp_3);
   1200     const __m128i a2 = _mm_sub_epi16(tmp_1, tmp_3);
   1201     const __m128i a3 = _mm_sub_epi16(tmp_0, tmp_2);
   1202     const __m128i b0 = _mm_add_epi16(a0, a1);
   1203     const __m128i b1 = _mm_add_epi16(a3, a2);
   1204     const __m128i b2 = _mm_sub_epi16(a3, a2);
   1205     const __m128i b3 = _mm_sub_epi16(a0, a1);
   1206     // a00 a01 a02 a03   b00 b01 b02 b03
   1207     // a10 a11 a12 a13   b10 b11 b12 b13
   1208     // a20 a21 a22 a23   b20 b21 b22 b23
   1209     // a30 a31 a32 a33   b30 b31 b32 b33
   1210 
   1211     // Transpose the two 4x4.
   1212     const __m128i transpose0_0 = _mm_unpacklo_epi16(b0, b1);
   1213     const __m128i transpose0_1 = _mm_unpacklo_epi16(b2, b3);
   1214     const __m128i transpose0_2 = _mm_unpackhi_epi16(b0, b1);
   1215     const __m128i transpose0_3 = _mm_unpackhi_epi16(b2, b3);
   1216     // a00 a10 a01 a11   a02 a12 a03 a13
   1217     // a20 a30 a21 a31   a22 a32 a23 a33
   1218     // b00 b10 b01 b11   b02 b12 b03 b13
   1219     // b20 b30 b21 b31   b22 b32 b23 b33
   1220     const __m128i transpose1_0 = _mm_unpacklo_epi32(transpose0_0, transpose0_1);
   1221     const __m128i transpose1_1 = _mm_unpacklo_epi32(transpose0_2, transpose0_3);
   1222     const __m128i transpose1_2 = _mm_unpackhi_epi32(transpose0_0, transpose0_1);
   1223     const __m128i transpose1_3 = _mm_unpackhi_epi32(transpose0_2, transpose0_3);
   1224     // a00 a10 a20 a30 a01 a11 a21 a31
   1225     // b00 b10 b20 b30 b01 b11 b21 b31
   1226     // a02 a12 a22 a32 a03 a13 a23 a33
   1227     // b02 b12 a22 b32 b03 b13 b23 b33
   1228     tmp_0 = _mm_unpacklo_epi64(transpose1_0, transpose1_1);
   1229     tmp_1 = _mm_unpackhi_epi64(transpose1_0, transpose1_1);
   1230     tmp_2 = _mm_unpacklo_epi64(transpose1_2, transpose1_3);
   1231     tmp_3 = _mm_unpackhi_epi64(transpose1_2, transpose1_3);
   1232     // a00 a10 a20 a30   b00 b10 b20 b30
   1233     // a01 a11 a21 a31   b01 b11 b21 b31
   1234     // a02 a12 a22 a32   b02 b12 b22 b32
   1235     // a03 a13 a23 a33   b03 b13 b23 b33
   1236   }
   1237 
   1238   // Vertical pass and difference of weighted sums.
   1239   {
   1240     // Load all inputs.
   1241     const __m128i w_0 = _mm_loadu_si128((const __m128i*)&w[0]);
   1242     const __m128i w_8 = _mm_loadu_si128((const __m128i*)&w[8]);
   1243 
   1244     // Calculate a and b (two 4x4 at once).
   1245     const __m128i a0 = _mm_add_epi16(tmp_0, tmp_2);
   1246     const __m128i a1 = _mm_add_epi16(tmp_1, tmp_3);
   1247     const __m128i a2 = _mm_sub_epi16(tmp_1, tmp_3);
   1248     const __m128i a3 = _mm_sub_epi16(tmp_0, tmp_2);
   1249     const __m128i b0 = _mm_add_epi16(a0, a1);
   1250     const __m128i b1 = _mm_add_epi16(a3, a2);
   1251     const __m128i b2 = _mm_sub_epi16(a3, a2);
   1252     const __m128i b3 = _mm_sub_epi16(a0, a1);
   1253 
   1254     // Separate the transforms of inA and inB.
   1255     __m128i A_b0 = _mm_unpacklo_epi64(b0, b1);
   1256     __m128i A_b2 = _mm_unpacklo_epi64(b2, b3);
   1257     __m128i B_b0 = _mm_unpackhi_epi64(b0, b1);
   1258     __m128i B_b2 = _mm_unpackhi_epi64(b2, b3);
   1259 
   1260     {
   1261       const __m128i d0 = _mm_sub_epi16(zero, A_b0);
   1262       const __m128i d1 = _mm_sub_epi16(zero, A_b2);
   1263       const __m128i d2 = _mm_sub_epi16(zero, B_b0);
   1264       const __m128i d3 = _mm_sub_epi16(zero, B_b2);
   1265       A_b0 = _mm_max_epi16(A_b0, d0);   // abs(v), 16b
   1266       A_b2 = _mm_max_epi16(A_b2, d1);
   1267       B_b0 = _mm_max_epi16(B_b0, d2);
   1268       B_b2 = _mm_max_epi16(B_b2, d3);
   1269     }
   1270 
   1271     // weighted sums
   1272     A_b0 = _mm_madd_epi16(A_b0, w_0);
   1273     A_b2 = _mm_madd_epi16(A_b2, w_8);
   1274     B_b0 = _mm_madd_epi16(B_b0, w_0);
   1275     B_b2 = _mm_madd_epi16(B_b2, w_8);
   1276     A_b0 = _mm_add_epi32(A_b0, A_b2);
   1277     B_b0 = _mm_add_epi32(B_b0, B_b2);
   1278 
   1279     // difference of weighted sums
   1280     A_b0 = _mm_sub_epi32(A_b0, B_b0);
   1281     _mm_storeu_si128((__m128i*)&sum[0], A_b0);
   1282   }
   1283   return sum[0] + sum[1] + sum[2] + sum[3];
   1284 }
   1285 
   1286 static int Disto4x4(const uint8_t* const a, const uint8_t* const b,
   1287                     const uint16_t* const w) {
   1288   const int diff_sum = TTransform(a, b, w);
   1289   return abs(diff_sum) >> 5;
   1290 }
   1291 
   1292 static int Disto16x16(const uint8_t* const a, const uint8_t* const b,
   1293                       const uint16_t* const w) {
   1294   int D = 0;
   1295   int x, y;
   1296   for (y = 0; y < 16 * BPS; y += 4 * BPS) {
   1297     for (x = 0; x < 16; x += 4) {
   1298       D += Disto4x4(a + x + y, b + x + y, w);
   1299     }
   1300   }
   1301   return D;
   1302 }
   1303 
   1304 //------------------------------------------------------------------------------
   1305 // Quantization
   1306 //
   1307 
   1308 static WEBP_INLINE int DoQuantizeBlock(int16_t in[16], int16_t out[16],
   1309                                        const uint16_t* const sharpen,
   1310                                        const VP8Matrix* const mtx) {
   1311   const __m128i max_coeff_2047 = _mm_set1_epi16(MAX_LEVEL);
   1312   const __m128i zero = _mm_setzero_si128();
   1313   __m128i coeff0, coeff8;
   1314   __m128i out0, out8;
   1315   __m128i packed_out;
   1316 
   1317   // Load all inputs.
   1318   __m128i in0 = _mm_loadu_si128((__m128i*)&in[0]);
   1319   __m128i in8 = _mm_loadu_si128((__m128i*)&in[8]);
   1320   const __m128i iq0 = _mm_loadu_si128((const __m128i*)&mtx->iq_[0]);
   1321   const __m128i iq8 = _mm_loadu_si128((const __m128i*)&mtx->iq_[8]);
   1322   const __m128i q0 = _mm_loadu_si128((const __m128i*)&mtx->q_[0]);
   1323   const __m128i q8 = _mm_loadu_si128((const __m128i*)&mtx->q_[8]);
   1324 
   1325   // extract sign(in)  (0x0000 if positive, 0xffff if negative)
   1326   const __m128i sign0 = _mm_cmpgt_epi16(zero, in0);
   1327   const __m128i sign8 = _mm_cmpgt_epi16(zero, in8);
   1328 
   1329   // coeff = abs(in) = (in ^ sign) - sign
   1330   coeff0 = _mm_xor_si128(in0, sign0);
   1331   coeff8 = _mm_xor_si128(in8, sign8);
   1332   coeff0 = _mm_sub_epi16(coeff0, sign0);
   1333   coeff8 = _mm_sub_epi16(coeff8, sign8);
   1334 
   1335   // coeff = abs(in) + sharpen
   1336   if (sharpen != NULL) {
   1337     const __m128i sharpen0 = _mm_loadu_si128((const __m128i*)&sharpen[0]);
   1338     const __m128i sharpen8 = _mm_loadu_si128((const __m128i*)&sharpen[8]);
   1339     coeff0 = _mm_add_epi16(coeff0, sharpen0);
   1340     coeff8 = _mm_add_epi16(coeff8, sharpen8);
   1341   }
   1342 
   1343   // out = (coeff * iQ + B) >> QFIX
   1344   {
   1345     // doing calculations with 32b precision (QFIX=17)
   1346     // out = (coeff * iQ)
   1347     const __m128i coeff_iQ0H = _mm_mulhi_epu16(coeff0, iq0);
   1348     const __m128i coeff_iQ0L = _mm_mullo_epi16(coeff0, iq0);
   1349     const __m128i coeff_iQ8H = _mm_mulhi_epu16(coeff8, iq8);
   1350     const __m128i coeff_iQ8L = _mm_mullo_epi16(coeff8, iq8);
   1351     __m128i out_00 = _mm_unpacklo_epi16(coeff_iQ0L, coeff_iQ0H);
   1352     __m128i out_04 = _mm_unpackhi_epi16(coeff_iQ0L, coeff_iQ0H);
   1353     __m128i out_08 = _mm_unpacklo_epi16(coeff_iQ8L, coeff_iQ8H);
   1354     __m128i out_12 = _mm_unpackhi_epi16(coeff_iQ8L, coeff_iQ8H);
   1355     // out = (coeff * iQ + B)
   1356     const __m128i bias_00 = _mm_loadu_si128((const __m128i*)&mtx->bias_[0]);
   1357     const __m128i bias_04 = _mm_loadu_si128((const __m128i*)&mtx->bias_[4]);
   1358     const __m128i bias_08 = _mm_loadu_si128((const __m128i*)&mtx->bias_[8]);
   1359     const __m128i bias_12 = _mm_loadu_si128((const __m128i*)&mtx->bias_[12]);
   1360     out_00 = _mm_add_epi32(out_00, bias_00);
   1361     out_04 = _mm_add_epi32(out_04, bias_04);
   1362     out_08 = _mm_add_epi32(out_08, bias_08);
   1363     out_12 = _mm_add_epi32(out_12, bias_12);
   1364     // out = QUANTDIV(coeff, iQ, B, QFIX)
   1365     out_00 = _mm_srai_epi32(out_00, QFIX);
   1366     out_04 = _mm_srai_epi32(out_04, QFIX);
   1367     out_08 = _mm_srai_epi32(out_08, QFIX);
   1368     out_12 = _mm_srai_epi32(out_12, QFIX);
   1369 
   1370     // pack result as 16b
   1371     out0 = _mm_packs_epi32(out_00, out_04);
   1372     out8 = _mm_packs_epi32(out_08, out_12);
   1373 
   1374     // if (coeff > 2047) coeff = 2047
   1375     out0 = _mm_min_epi16(out0, max_coeff_2047);
   1376     out8 = _mm_min_epi16(out8, max_coeff_2047);
   1377   }
   1378 
   1379   // get sign back (if (sign[j]) out_n = -out_n)
   1380   out0 = _mm_xor_si128(out0, sign0);
   1381   out8 = _mm_xor_si128(out8, sign8);
   1382   out0 = _mm_sub_epi16(out0, sign0);
   1383   out8 = _mm_sub_epi16(out8, sign8);
   1384 
   1385   // in = out * Q
   1386   in0 = _mm_mullo_epi16(out0, q0);
   1387   in8 = _mm_mullo_epi16(out8, q8);
   1388 
   1389   _mm_storeu_si128((__m128i*)&in[0], in0);
   1390   _mm_storeu_si128((__m128i*)&in[8], in8);
   1391 
   1392   // zigzag the output before storing it.
   1393   //
   1394   // The zigzag pattern can almost be reproduced with a small sequence of
   1395   // shuffles. After it, we only need to swap the 7th (ending up in third
   1396   // position instead of twelfth) and 8th values.
   1397   {
   1398     __m128i outZ0, outZ8;
   1399     outZ0 = _mm_shufflehi_epi16(out0,  _MM_SHUFFLE(2, 1, 3, 0));
   1400     outZ0 = _mm_shuffle_epi32  (outZ0, _MM_SHUFFLE(3, 1, 2, 0));
   1401     outZ0 = _mm_shufflehi_epi16(outZ0, _MM_SHUFFLE(3, 1, 0, 2));
   1402     outZ8 = _mm_shufflelo_epi16(out8,  _MM_SHUFFLE(3, 0, 2, 1));
   1403     outZ8 = _mm_shuffle_epi32  (outZ8, _MM_SHUFFLE(3, 1, 2, 0));
   1404     outZ8 = _mm_shufflelo_epi16(outZ8, _MM_SHUFFLE(1, 3, 2, 0));
   1405     _mm_storeu_si128((__m128i*)&out[0], outZ0);
   1406     _mm_storeu_si128((__m128i*)&out[8], outZ8);
   1407     packed_out = _mm_packs_epi16(outZ0, outZ8);
   1408   }
   1409   {
   1410     const int16_t outZ_12 = out[12];
   1411     const int16_t outZ_3 = out[3];
   1412     out[3] = outZ_12;
   1413     out[12] = outZ_3;
   1414   }
   1415 
   1416   // detect if all 'out' values are zeroes or not
   1417   return (_mm_movemask_epi8(_mm_cmpeq_epi8(packed_out, zero)) != 0xffff);
   1418 }
   1419 
   1420 static int QuantizeBlock(int16_t in[16], int16_t out[16],
   1421                          const VP8Matrix* const mtx) {
   1422   return DoQuantizeBlock(in, out, &mtx->sharpen_[0], mtx);
   1423 }
   1424 
   1425 static int QuantizeBlockWHT(int16_t in[16], int16_t out[16],
   1426                             const VP8Matrix* const mtx) {
   1427   return DoQuantizeBlock(in, out, NULL, mtx);
   1428 }
   1429 
   1430 static int Quantize2Blocks(int16_t in[32], int16_t out[32],
   1431                            const VP8Matrix* const mtx) {
   1432   int nz;
   1433   const uint16_t* const sharpen = &mtx->sharpen_[0];
   1434   nz  = DoQuantizeBlock(in + 0 * 16, out + 0 * 16, sharpen, mtx) << 0;
   1435   nz |= DoQuantizeBlock(in + 1 * 16, out + 1 * 16, sharpen, mtx) << 1;
   1436   return nz;
   1437 }
   1438 
   1439 //------------------------------------------------------------------------------
   1440 // Entry point
   1441 
   1442 extern void VP8EncDspInitSSE2(void);
   1443 
   1444 WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspInitSSE2(void) {
   1445   VP8CollectHistogram = CollectHistogram;
   1446   VP8EncPredLuma16 = Intra16Preds;
   1447   VP8EncPredChroma8 = IntraChromaPreds;
   1448   VP8EncPredLuma4 = Intra4Preds;
   1449   VP8EncQuantizeBlock = QuantizeBlock;
   1450   VP8EncQuantize2Blocks = Quantize2Blocks;
   1451   VP8EncQuantizeBlockWHT = QuantizeBlockWHT;
   1452   VP8ITransform = ITransform;
   1453   VP8FTransform = FTransform;
   1454   VP8FTransform2 = FTransform2;
   1455   VP8FTransformWHT = FTransformWHT;
   1456   VP8SSE16x16 = SSE16x16;
   1457   VP8SSE16x8 = SSE16x8;
   1458   VP8SSE8x8 = SSE8x8;
   1459   VP8SSE4x4 = SSE4x4;
   1460   VP8TDisto4x4 = Disto4x4;
   1461   VP8TDisto16x16 = Disto16x16;
   1462 }
   1463 
   1464 #else  // !WEBP_USE_SSE2
   1465 
   1466 WEBP_DSP_INIT_STUB(VP8EncDspInitSSE2)
   1467 
   1468 #endif  // WEBP_USE_SSE2
   1469