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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 // Speed-critical encoding functions.
     11 //
     12 // Author: Skal (pascal.massimino (at) gmail.com)
     13 
     14 #include <assert.h>
     15 #include <stdlib.h>  // for abs()
     16 
     17 #include "src/dsp/dsp.h"
     18 #include "src/enc/vp8i_enc.h"
     19 
     20 static WEBP_INLINE uint8_t clip_8b(int v) {
     21   return (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
     22 }
     23 
     24 #if !WEBP_NEON_OMIT_C_CODE
     25 static WEBP_INLINE int clip_max(int v, int max) {
     26   return (v > max) ? max : v;
     27 }
     28 #endif  // !WEBP_NEON_OMIT_C_CODE
     29 
     30 //------------------------------------------------------------------------------
     31 // Compute susceptibility based on DCT-coeff histograms:
     32 // the higher, the "easier" the macroblock is to compress.
     33 
     34 const int VP8DspScan[16 + 4 + 4] = {
     35   // Luma
     36   0 +  0 * BPS,  4 +  0 * BPS, 8 +  0 * BPS, 12 +  0 * BPS,
     37   0 +  4 * BPS,  4 +  4 * BPS, 8 +  4 * BPS, 12 +  4 * BPS,
     38   0 +  8 * BPS,  4 +  8 * BPS, 8 +  8 * BPS, 12 +  8 * BPS,
     39   0 + 12 * BPS,  4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS,
     40 
     41   0 + 0 * BPS,   4 + 0 * BPS, 0 + 4 * BPS,  4 + 4 * BPS,    // U
     42   8 + 0 * BPS,  12 + 0 * BPS, 8 + 4 * BPS, 12 + 4 * BPS     // V
     43 };
     44 
     45 // general-purpose util function
     46 void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
     47                          VP8Histogram* const histo) {
     48   int max_value = 0, last_non_zero = 1;
     49   int k;
     50   for (k = 0; k <= MAX_COEFF_THRESH; ++k) {
     51     const int value = distribution[k];
     52     if (value > 0) {
     53       if (value > max_value) max_value = value;
     54       last_non_zero = k;
     55     }
     56   }
     57   histo->max_value = max_value;
     58   histo->last_non_zero = last_non_zero;
     59 }
     60 
     61 #if !WEBP_NEON_OMIT_C_CODE
     62 static void CollectHistogram_C(const uint8_t* ref, const uint8_t* pred,
     63                                int start_block, int end_block,
     64                                VP8Histogram* const histo) {
     65   int j;
     66   int distribution[MAX_COEFF_THRESH + 1] = { 0 };
     67   for (j = start_block; j < end_block; ++j) {
     68     int k;
     69     int16_t out[16];
     70 
     71     VP8FTransform(ref + VP8DspScan[j], pred + VP8DspScan[j], out);
     72 
     73     // Convert coefficients to bin.
     74     for (k = 0; k < 16; ++k) {
     75       const int v = abs(out[k]) >> 3;
     76       const int clipped_value = clip_max(v, MAX_COEFF_THRESH);
     77       ++distribution[clipped_value];
     78     }
     79   }
     80   VP8SetHistogramData(distribution, histo);
     81 }
     82 #endif  // !WEBP_NEON_OMIT_C_CODE
     83 
     84 //------------------------------------------------------------------------------
     85 // run-time tables (~4k)
     86 
     87 static uint8_t clip1[255 + 510 + 1];    // clips [-255,510] to [0,255]
     88 
     89 // We declare this variable 'volatile' to prevent instruction reordering
     90 // and make sure it's set to true _last_ (so as to be thread-safe)
     91 static volatile int tables_ok = 0;
     92 
     93 static WEBP_TSAN_IGNORE_FUNCTION void InitTables(void) {
     94   if (!tables_ok) {
     95     int i;
     96     for (i = -255; i <= 255 + 255; ++i) {
     97       clip1[255 + i] = clip_8b(i);
     98     }
     99     tables_ok = 1;
    100   }
    101 }
    102 
    103 
    104 //------------------------------------------------------------------------------
    105 // Transforms (Paragraph 14.4)
    106 
    107 #if !WEBP_NEON_OMIT_C_CODE
    108 
    109 #define STORE(x, y, v) \
    110   dst[(x) + (y) * BPS] = clip_8b(ref[(x) + (y) * BPS] + ((v) >> 3))
    111 
    112 static const int kC1 = 20091 + (1 << 16);
    113 static const int kC2 = 35468;
    114 #define MUL(a, b) (((a) * (b)) >> 16)
    115 
    116 static WEBP_INLINE void ITransformOne(const uint8_t* ref, const int16_t* in,
    117                                       uint8_t* dst) {
    118   int C[4 * 4], *tmp;
    119   int i;
    120   tmp = C;
    121   for (i = 0; i < 4; ++i) {    // vertical pass
    122     const int a = in[0] + in[8];
    123     const int b = in[0] - in[8];
    124     const int c = MUL(in[4], kC2) - MUL(in[12], kC1);
    125     const int d = MUL(in[4], kC1) + MUL(in[12], kC2);
    126     tmp[0] = a + d;
    127     tmp[1] = b + c;
    128     tmp[2] = b - c;
    129     tmp[3] = a - d;
    130     tmp += 4;
    131     in++;
    132   }
    133 
    134   tmp = C;
    135   for (i = 0; i < 4; ++i) {    // horizontal pass
    136     const int dc = tmp[0] + 4;
    137     const int a =  dc +  tmp[8];
    138     const int b =  dc -  tmp[8];
    139     const int c = MUL(tmp[4], kC2) - MUL(tmp[12], kC1);
    140     const int d = MUL(tmp[4], kC1) + MUL(tmp[12], kC2);
    141     STORE(0, i, a + d);
    142     STORE(1, i, b + c);
    143     STORE(2, i, b - c);
    144     STORE(3, i, a - d);
    145     tmp++;
    146   }
    147 }
    148 
    149 static void ITransform_C(const uint8_t* ref, const int16_t* in, uint8_t* dst,
    150                          int do_two) {
    151   ITransformOne(ref, in, dst);
    152   if (do_two) {
    153     ITransformOne(ref + 4, in + 16, dst + 4);
    154   }
    155 }
    156 
    157 static void FTransform_C(const uint8_t* src, const uint8_t* ref, int16_t* out) {
    158   int i;
    159   int tmp[16];
    160   for (i = 0; i < 4; ++i, src += BPS, ref += BPS) {
    161     const int d0 = src[0] - ref[0];   // 9bit dynamic range ([-255,255])
    162     const int d1 = src[1] - ref[1];
    163     const int d2 = src[2] - ref[2];
    164     const int d3 = src[3] - ref[3];
    165     const int a0 = (d0 + d3);         // 10b                      [-510,510]
    166     const int a1 = (d1 + d2);
    167     const int a2 = (d1 - d2);
    168     const int a3 = (d0 - d3);
    169     tmp[0 + i * 4] = (a0 + a1) * 8;   // 14b                      [-8160,8160]
    170     tmp[1 + i * 4] = (a2 * 2217 + a3 * 5352 + 1812) >> 9;      // [-7536,7542]
    171     tmp[2 + i * 4] = (a0 - a1) * 8;
    172     tmp[3 + i * 4] = (a3 * 2217 - a2 * 5352 +  937) >> 9;
    173   }
    174   for (i = 0; i < 4; ++i) {
    175     const int a0 = (tmp[0 + i] + tmp[12 + i]);  // 15b
    176     const int a1 = (tmp[4 + i] + tmp[ 8 + i]);
    177     const int a2 = (tmp[4 + i] - tmp[ 8 + i]);
    178     const int a3 = (tmp[0 + i] - tmp[12 + i]);
    179     out[0 + i] = (a0 + a1 + 7) >> 4;            // 12b
    180     out[4 + i] = ((a2 * 2217 + a3 * 5352 + 12000) >> 16) + (a3 != 0);
    181     out[8 + i] = (a0 - a1 + 7) >> 4;
    182     out[12+ i] = ((a3 * 2217 - a2 * 5352 + 51000) >> 16);
    183   }
    184 }
    185 #endif  // !WEBP_NEON_OMIT_C_CODE
    186 
    187 static void FTransform2_C(const uint8_t* src, const uint8_t* ref,
    188                           int16_t* out) {
    189   VP8FTransform(src, ref, out);
    190   VP8FTransform(src + 4, ref + 4, out + 16);
    191 }
    192 
    193 #if !WEBP_NEON_OMIT_C_CODE
    194 static void FTransformWHT_C(const int16_t* in, int16_t* out) {
    195   // input is 12b signed
    196   int32_t tmp[16];
    197   int i;
    198   for (i = 0; i < 4; ++i, in += 64) {
    199     const int a0 = (in[0 * 16] + in[2 * 16]);  // 13b
    200     const int a1 = (in[1 * 16] + in[3 * 16]);
    201     const int a2 = (in[1 * 16] - in[3 * 16]);
    202     const int a3 = (in[0 * 16] - in[2 * 16]);
    203     tmp[0 + i * 4] = a0 + a1;   // 14b
    204     tmp[1 + i * 4] = a3 + a2;
    205     tmp[2 + i * 4] = a3 - a2;
    206     tmp[3 + i * 4] = a0 - a1;
    207   }
    208   for (i = 0; i < 4; ++i) {
    209     const int a0 = (tmp[0 + i] + tmp[8 + i]);  // 15b
    210     const int a1 = (tmp[4 + i] + tmp[12+ i]);
    211     const int a2 = (tmp[4 + i] - tmp[12+ i]);
    212     const int a3 = (tmp[0 + i] - tmp[8 + i]);
    213     const int b0 = a0 + a1;    // 16b
    214     const int b1 = a3 + a2;
    215     const int b2 = a3 - a2;
    216     const int b3 = a0 - a1;
    217     out[ 0 + i] = b0 >> 1;     // 15b
    218     out[ 4 + i] = b1 >> 1;
    219     out[ 8 + i] = b2 >> 1;
    220     out[12 + i] = b3 >> 1;
    221   }
    222 }
    223 #endif  // !WEBP_NEON_OMIT_C_CODE
    224 
    225 #undef MUL
    226 #undef STORE
    227 
    228 //------------------------------------------------------------------------------
    229 // Intra predictions
    230 
    231 static WEBP_INLINE void Fill(uint8_t* dst, int value, int size) {
    232   int j;
    233   for (j = 0; j < size; ++j) {
    234     memset(dst + j * BPS, value, size);
    235   }
    236 }
    237 
    238 static WEBP_INLINE void VerticalPred(uint8_t* dst,
    239                                      const uint8_t* top, int size) {
    240   int j;
    241   if (top != NULL) {
    242     for (j = 0; j < size; ++j) memcpy(dst + j * BPS, top, size);
    243   } else {
    244     Fill(dst, 127, size);
    245   }
    246 }
    247 
    248 static WEBP_INLINE void HorizontalPred(uint8_t* dst,
    249                                        const uint8_t* left, int size) {
    250   if (left != NULL) {
    251     int j;
    252     for (j = 0; j < size; ++j) {
    253       memset(dst + j * BPS, left[j], size);
    254     }
    255   } else {
    256     Fill(dst, 129, size);
    257   }
    258 }
    259 
    260 static WEBP_INLINE void TrueMotion(uint8_t* dst, const uint8_t* left,
    261                                    const uint8_t* top, int size) {
    262   int y;
    263   if (left != NULL) {
    264     if (top != NULL) {
    265       const uint8_t* const clip = clip1 + 255 - left[-1];
    266       for (y = 0; y < size; ++y) {
    267         const uint8_t* const clip_table = clip + left[y];
    268         int x;
    269         for (x = 0; x < size; ++x) {
    270           dst[x] = clip_table[top[x]];
    271         }
    272         dst += BPS;
    273       }
    274     } else {
    275       HorizontalPred(dst, left, size);
    276     }
    277   } else {
    278     // true motion without left samples (hence: with default 129 value)
    279     // is equivalent to VE prediction where you just copy the top samples.
    280     // Note that if top samples are not available, the default value is
    281     // then 129, and not 127 as in the VerticalPred case.
    282     if (top != NULL) {
    283       VerticalPred(dst, top, size);
    284     } else {
    285       Fill(dst, 129, size);
    286     }
    287   }
    288 }
    289 
    290 static WEBP_INLINE void DCMode(uint8_t* dst, const uint8_t* left,
    291                                const uint8_t* top,
    292                                int size, int round, int shift) {
    293   int DC = 0;
    294   int j;
    295   if (top != NULL) {
    296     for (j = 0; j < size; ++j) DC += top[j];
    297     if (left != NULL) {   // top and left present
    298       for (j = 0; j < size; ++j) DC += left[j];
    299     } else {      // top, but no left
    300       DC += DC;
    301     }
    302     DC = (DC + round) >> shift;
    303   } else if (left != NULL) {   // left but no top
    304     for (j = 0; j < size; ++j) DC += left[j];
    305     DC += DC;
    306     DC = (DC + round) >> shift;
    307   } else {   // no top, no left, nothing.
    308     DC = 0x80;
    309   }
    310   Fill(dst, DC, size);
    311 }
    312 
    313 //------------------------------------------------------------------------------
    314 // Chroma 8x8 prediction (paragraph 12.2)
    315 
    316 static void IntraChromaPreds_C(uint8_t* dst, const uint8_t* left,
    317                                const uint8_t* top) {
    318   // U block
    319   DCMode(C8DC8 + dst, left, top, 8, 8, 4);
    320   VerticalPred(C8VE8 + dst, top, 8);
    321   HorizontalPred(C8HE8 + dst, left, 8);
    322   TrueMotion(C8TM8 + dst, left, top, 8);
    323   // V block
    324   dst += 8;
    325   if (top != NULL) top += 8;
    326   if (left != NULL) left += 16;
    327   DCMode(C8DC8 + dst, left, top, 8, 8, 4);
    328   VerticalPred(C8VE8 + dst, top, 8);
    329   HorizontalPred(C8HE8 + dst, left, 8);
    330   TrueMotion(C8TM8 + dst, left, top, 8);
    331 }
    332 
    333 //------------------------------------------------------------------------------
    334 // luma 16x16 prediction (paragraph 12.3)
    335 
    336 static void Intra16Preds_C(uint8_t* dst,
    337                            const uint8_t* left, const uint8_t* top) {
    338   DCMode(I16DC16 + dst, left, top, 16, 16, 5);
    339   VerticalPred(I16VE16 + dst, top, 16);
    340   HorizontalPred(I16HE16 + dst, left, 16);
    341   TrueMotion(I16TM16 + dst, left, top, 16);
    342 }
    343 
    344 //------------------------------------------------------------------------------
    345 // luma 4x4 prediction
    346 
    347 #define DST(x, y) dst[(x) + (y) * BPS]
    348 #define AVG3(a, b, c) ((uint8_t)(((a) + 2 * (b) + (c) + 2) >> 2))
    349 #define AVG2(a, b) (((a) + (b) + 1) >> 1)
    350 
    351 static void VE4(uint8_t* dst, const uint8_t* top) {    // vertical
    352   const uint8_t vals[4] = {
    353     AVG3(top[-1], top[0], top[1]),
    354     AVG3(top[ 0], top[1], top[2]),
    355     AVG3(top[ 1], top[2], top[3]),
    356     AVG3(top[ 2], top[3], top[4])
    357   };
    358   int i;
    359   for (i = 0; i < 4; ++i) {
    360     memcpy(dst + i * BPS, vals, 4);
    361   }
    362 }
    363 
    364 static void HE4(uint8_t* dst, const uint8_t* top) {    // horizontal
    365   const int X = top[-1];
    366   const int I = top[-2];
    367   const int J = top[-3];
    368   const int K = top[-4];
    369   const int L = top[-5];
    370   WebPUint32ToMem(dst + 0 * BPS, 0x01010101U * AVG3(X, I, J));
    371   WebPUint32ToMem(dst + 1 * BPS, 0x01010101U * AVG3(I, J, K));
    372   WebPUint32ToMem(dst + 2 * BPS, 0x01010101U * AVG3(J, K, L));
    373   WebPUint32ToMem(dst + 3 * BPS, 0x01010101U * AVG3(K, L, L));
    374 }
    375 
    376 static void DC4(uint8_t* dst, const uint8_t* top) {
    377   uint32_t dc = 4;
    378   int i;
    379   for (i = 0; i < 4; ++i) dc += top[i] + top[-5 + i];
    380   Fill(dst, dc >> 3, 4);
    381 }
    382 
    383 static void RD4(uint8_t* dst, const uint8_t* top) {
    384   const int X = top[-1];
    385   const int I = top[-2];
    386   const int J = top[-3];
    387   const int K = top[-4];
    388   const int L = top[-5];
    389   const int A = top[0];
    390   const int B = top[1];
    391   const int C = top[2];
    392   const int D = top[3];
    393   DST(0, 3)                                     = AVG3(J, K, L);
    394   DST(0, 2) = DST(1, 3)                         = AVG3(I, J, K);
    395   DST(0, 1) = DST(1, 2) = DST(2, 3)             = AVG3(X, I, J);
    396   DST(0, 0) = DST(1, 1) = DST(2, 2) = DST(3, 3) = AVG3(A, X, I);
    397   DST(1, 0) = DST(2, 1) = DST(3, 2)             = AVG3(B, A, X);
    398   DST(2, 0) = DST(3, 1)                         = AVG3(C, B, A);
    399   DST(3, 0)                                     = AVG3(D, C, B);
    400 }
    401 
    402 static void LD4(uint8_t* dst, const uint8_t* top) {
    403   const int A = top[0];
    404   const int B = top[1];
    405   const int C = top[2];
    406   const int D = top[3];
    407   const int E = top[4];
    408   const int F = top[5];
    409   const int G = top[6];
    410   const int H = top[7];
    411   DST(0, 0)                                     = AVG3(A, B, C);
    412   DST(1, 0) = DST(0, 1)                         = AVG3(B, C, D);
    413   DST(2, 0) = DST(1, 1) = DST(0, 2)             = AVG3(C, D, E);
    414   DST(3, 0) = DST(2, 1) = DST(1, 2) = DST(0, 3) = AVG3(D, E, F);
    415   DST(3, 1) = DST(2, 2) = DST(1, 3)             = AVG3(E, F, G);
    416   DST(3, 2) = DST(2, 3)                         = AVG3(F, G, H);
    417   DST(3, 3)                                     = AVG3(G, H, H);
    418 }
    419 
    420 static void VR4(uint8_t* dst, const uint8_t* top) {
    421   const int X = top[-1];
    422   const int I = top[-2];
    423   const int J = top[-3];
    424   const int K = top[-4];
    425   const int A = top[0];
    426   const int B = top[1];
    427   const int C = top[2];
    428   const int D = top[3];
    429   DST(0, 0) = DST(1, 2) = AVG2(X, A);
    430   DST(1, 0) = DST(2, 2) = AVG2(A, B);
    431   DST(2, 0) = DST(3, 2) = AVG2(B, C);
    432   DST(3, 0)             = AVG2(C, D);
    433 
    434   DST(0, 3) =             AVG3(K, J, I);
    435   DST(0, 2) =             AVG3(J, I, X);
    436   DST(0, 1) = DST(1, 3) = AVG3(I, X, A);
    437   DST(1, 1) = DST(2, 3) = AVG3(X, A, B);
    438   DST(2, 1) = DST(3, 3) = AVG3(A, B, C);
    439   DST(3, 1) =             AVG3(B, C, D);
    440 }
    441 
    442 static void VL4(uint8_t* dst, const uint8_t* top) {
    443   const int A = top[0];
    444   const int B = top[1];
    445   const int C = top[2];
    446   const int D = top[3];
    447   const int E = top[4];
    448   const int F = top[5];
    449   const int G = top[6];
    450   const int H = top[7];
    451   DST(0, 0) =             AVG2(A, B);
    452   DST(1, 0) = DST(0, 2) = AVG2(B, C);
    453   DST(2, 0) = DST(1, 2) = AVG2(C, D);
    454   DST(3, 0) = DST(2, 2) = AVG2(D, E);
    455 
    456   DST(0, 1) =             AVG3(A, B, C);
    457   DST(1, 1) = DST(0, 3) = AVG3(B, C, D);
    458   DST(2, 1) = DST(1, 3) = AVG3(C, D, E);
    459   DST(3, 1) = DST(2, 3) = AVG3(D, E, F);
    460               DST(3, 2) = AVG3(E, F, G);
    461               DST(3, 3) = AVG3(F, G, H);
    462 }
    463 
    464 static void HU4(uint8_t* dst, const uint8_t* top) {
    465   const int I = top[-2];
    466   const int J = top[-3];
    467   const int K = top[-4];
    468   const int L = top[-5];
    469   DST(0, 0) =             AVG2(I, J);
    470   DST(2, 0) = DST(0, 1) = AVG2(J, K);
    471   DST(2, 1) = DST(0, 2) = AVG2(K, L);
    472   DST(1, 0) =             AVG3(I, J, K);
    473   DST(3, 0) = DST(1, 1) = AVG3(J, K, L);
    474   DST(3, 1) = DST(1, 2) = AVG3(K, L, L);
    475   DST(3, 2) = DST(2, 2) =
    476   DST(0, 3) = DST(1, 3) = DST(2, 3) = DST(3, 3) = L;
    477 }
    478 
    479 static void HD4(uint8_t* dst, const uint8_t* top) {
    480   const int X = top[-1];
    481   const int I = top[-2];
    482   const int J = top[-3];
    483   const int K = top[-4];
    484   const int L = top[-5];
    485   const int A = top[0];
    486   const int B = top[1];
    487   const int C = top[2];
    488 
    489   DST(0, 0) = DST(2, 1) = AVG2(I, X);
    490   DST(0, 1) = DST(2, 2) = AVG2(J, I);
    491   DST(0, 2) = DST(2, 3) = AVG2(K, J);
    492   DST(0, 3)             = AVG2(L, K);
    493 
    494   DST(3, 0)             = AVG3(A, B, C);
    495   DST(2, 0)             = AVG3(X, A, B);
    496   DST(1, 0) = DST(3, 1) = AVG3(I, X, A);
    497   DST(1, 1) = DST(3, 2) = AVG3(J, I, X);
    498   DST(1, 2) = DST(3, 3) = AVG3(K, J, I);
    499   DST(1, 3)             = AVG3(L, K, J);
    500 }
    501 
    502 static void TM4(uint8_t* dst, const uint8_t* top) {
    503   int x, y;
    504   const uint8_t* const clip = clip1 + 255 - top[-1];
    505   for (y = 0; y < 4; ++y) {
    506     const uint8_t* const clip_table = clip + top[-2 - y];
    507     for (x = 0; x < 4; ++x) {
    508       dst[x] = clip_table[top[x]];
    509     }
    510     dst += BPS;
    511   }
    512 }
    513 
    514 #undef DST
    515 #undef AVG3
    516 #undef AVG2
    517 
    518 // Left samples are top[-5 .. -2], top_left is top[-1], top are
    519 // located at top[0..3], and top right is top[4..7]
    520 static void Intra4Preds_C(uint8_t* dst, const uint8_t* top) {
    521   DC4(I4DC4 + dst, top);
    522   TM4(I4TM4 + dst, top);
    523   VE4(I4VE4 + dst, top);
    524   HE4(I4HE4 + dst, top);
    525   RD4(I4RD4 + dst, top);
    526   VR4(I4VR4 + dst, top);
    527   LD4(I4LD4 + dst, top);
    528   VL4(I4VL4 + dst, top);
    529   HD4(I4HD4 + dst, top);
    530   HU4(I4HU4 + dst, top);
    531 }
    532 
    533 //------------------------------------------------------------------------------
    534 // Metric
    535 
    536 #if !WEBP_NEON_OMIT_C_CODE
    537 static WEBP_INLINE int GetSSE(const uint8_t* a, const uint8_t* b,
    538                               int w, int h) {
    539   int count = 0;
    540   int y, x;
    541   for (y = 0; y < h; ++y) {
    542     for (x = 0; x < w; ++x) {
    543       const int diff = (int)a[x] - b[x];
    544       count += diff * diff;
    545     }
    546     a += BPS;
    547     b += BPS;
    548   }
    549   return count;
    550 }
    551 
    552 static int SSE16x16_C(const uint8_t* a, const uint8_t* b) {
    553   return GetSSE(a, b, 16, 16);
    554 }
    555 static int SSE16x8_C(const uint8_t* a, const uint8_t* b) {
    556   return GetSSE(a, b, 16, 8);
    557 }
    558 static int SSE8x8_C(const uint8_t* a, const uint8_t* b) {
    559   return GetSSE(a, b, 8, 8);
    560 }
    561 static int SSE4x4_C(const uint8_t* a, const uint8_t* b) {
    562   return GetSSE(a, b, 4, 4);
    563 }
    564 #endif  // !WEBP_NEON_OMIT_C_CODE
    565 
    566 static void Mean16x4_C(const uint8_t* ref, uint32_t dc[4]) {
    567   int k, x, y;
    568   for (k = 0; k < 4; ++k) {
    569     uint32_t avg = 0;
    570     for (y = 0; y < 4; ++y) {
    571       for (x = 0; x < 4; ++x) {
    572         avg += ref[x + y * BPS];
    573       }
    574     }
    575     dc[k] = avg;
    576     ref += 4;   // go to next 4x4 block.
    577   }
    578 }
    579 
    580 //------------------------------------------------------------------------------
    581 // Texture distortion
    582 //
    583 // We try to match the spectral content (weighted) between source and
    584 // reconstructed samples.
    585 
    586 #if !WEBP_NEON_OMIT_C_CODE
    587 // Hadamard transform
    588 // Returns the weighted sum of the absolute value of transformed coefficients.
    589 // w[] contains a row-major 4 by 4 symmetric matrix.
    590 static int TTransform(const uint8_t* in, const uint16_t* w) {
    591   int sum = 0;
    592   int tmp[16];
    593   int i;
    594   // horizontal pass
    595   for (i = 0; i < 4; ++i, in += BPS) {
    596     const int a0 = in[0] + in[2];
    597     const int a1 = in[1] + in[3];
    598     const int a2 = in[1] - in[3];
    599     const int a3 = in[0] - in[2];
    600     tmp[0 + i * 4] = a0 + a1;
    601     tmp[1 + i * 4] = a3 + a2;
    602     tmp[2 + i * 4] = a3 - a2;
    603     tmp[3 + i * 4] = a0 - a1;
    604   }
    605   // vertical pass
    606   for (i = 0; i < 4; ++i, ++w) {
    607     const int a0 = tmp[0 + i] + tmp[8 + i];
    608     const int a1 = tmp[4 + i] + tmp[12+ i];
    609     const int a2 = tmp[4 + i] - tmp[12+ i];
    610     const int a3 = tmp[0 + i] - tmp[8 + i];
    611     const int b0 = a0 + a1;
    612     const int b1 = a3 + a2;
    613     const int b2 = a3 - a2;
    614     const int b3 = a0 - a1;
    615 
    616     sum += w[ 0] * abs(b0);
    617     sum += w[ 4] * abs(b1);
    618     sum += w[ 8] * abs(b2);
    619     sum += w[12] * abs(b3);
    620   }
    621   return sum;
    622 }
    623 
    624 static int Disto4x4_C(const uint8_t* const a, const uint8_t* const b,
    625                       const uint16_t* const w) {
    626   const int sum1 = TTransform(a, w);
    627   const int sum2 = TTransform(b, w);
    628   return abs(sum2 - sum1) >> 5;
    629 }
    630 
    631 static int Disto16x16_C(const uint8_t* const a, const uint8_t* const b,
    632                         const uint16_t* const w) {
    633   int D = 0;
    634   int x, y;
    635   for (y = 0; y < 16 * BPS; y += 4 * BPS) {
    636     for (x = 0; x < 16; x += 4) {
    637       D += Disto4x4_C(a + x + y, b + x + y, w);
    638     }
    639   }
    640   return D;
    641 }
    642 #endif  // !WEBP_NEON_OMIT_C_CODE
    643 
    644 //------------------------------------------------------------------------------
    645 // Quantization
    646 //
    647 
    648 static const uint8_t kZigzag[16] = {
    649   0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
    650 };
    651 
    652 // Simple quantization
    653 static int QuantizeBlock_C(int16_t in[16], int16_t out[16],
    654                            const VP8Matrix* const mtx) {
    655   int last = -1;
    656   int n;
    657   for (n = 0; n < 16; ++n) {
    658     const int j = kZigzag[n];
    659     const int sign = (in[j] < 0);
    660     const uint32_t coeff = (sign ? -in[j] : in[j]) + mtx->sharpen_[j];
    661     if (coeff > mtx->zthresh_[j]) {
    662       const uint32_t Q = mtx->q_[j];
    663       const uint32_t iQ = mtx->iq_[j];
    664       const uint32_t B = mtx->bias_[j];
    665       int level = QUANTDIV(coeff, iQ, B);
    666       if (level > MAX_LEVEL) level = MAX_LEVEL;
    667       if (sign) level = -level;
    668       in[j] = level * (int)Q;
    669       out[n] = level;
    670       if (level) last = n;
    671     } else {
    672       out[n] = 0;
    673       in[j] = 0;
    674     }
    675   }
    676   return (last >= 0);
    677 }
    678 
    679 #if !WEBP_NEON_OMIT_C_CODE || WEBP_NEON_WORK_AROUND_GCC
    680 static int Quantize2Blocks_C(int16_t in[32], int16_t out[32],
    681                              const VP8Matrix* const mtx) {
    682   int nz;
    683   nz  = VP8EncQuantizeBlock(in + 0 * 16, out + 0 * 16, mtx) << 0;
    684   nz |= VP8EncQuantizeBlock(in + 1 * 16, out + 1 * 16, mtx) << 1;
    685   return nz;
    686 }
    687 #endif  // !WEBP_NEON_OMIT_C_CODE || WEBP_NEON_WORK_AROUND_GCC
    688 
    689 //------------------------------------------------------------------------------
    690 // Block copy
    691 
    692 static WEBP_INLINE void Copy(const uint8_t* src, uint8_t* dst, int w, int h) {
    693   int y;
    694   for (y = 0; y < h; ++y) {
    695     memcpy(dst, src, w);
    696     src += BPS;
    697     dst += BPS;
    698   }
    699 }
    700 
    701 static void Copy4x4_C(const uint8_t* src, uint8_t* dst) {
    702   Copy(src, dst, 4, 4);
    703 }
    704 
    705 static void Copy16x8_C(const uint8_t* src, uint8_t* dst) {
    706   Copy(src, dst, 16, 8);
    707 }
    708 
    709 //------------------------------------------------------------------------------
    710 // Initialization
    711 
    712 // Speed-critical function pointers. We have to initialize them to the default
    713 // implementations within VP8EncDspInit().
    714 VP8CHisto VP8CollectHistogram;
    715 VP8Idct VP8ITransform;
    716 VP8Fdct VP8FTransform;
    717 VP8Fdct VP8FTransform2;
    718 VP8WHT VP8FTransformWHT;
    719 VP8Intra4Preds VP8EncPredLuma4;
    720 VP8IntraPreds VP8EncPredLuma16;
    721 VP8IntraPreds VP8EncPredChroma8;
    722 VP8Metric VP8SSE16x16;
    723 VP8Metric VP8SSE8x8;
    724 VP8Metric VP8SSE16x8;
    725 VP8Metric VP8SSE4x4;
    726 VP8WMetric VP8TDisto4x4;
    727 VP8WMetric VP8TDisto16x16;
    728 VP8MeanMetric VP8Mean16x4;
    729 VP8QuantizeBlock VP8EncQuantizeBlock;
    730 VP8Quantize2Blocks VP8EncQuantize2Blocks;
    731 VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
    732 VP8BlockCopy VP8Copy4x4;
    733 VP8BlockCopy VP8Copy16x8;
    734 
    735 extern void VP8EncDspInitSSE2(void);
    736 extern void VP8EncDspInitSSE41(void);
    737 extern void VP8EncDspInitAVX2(void);
    738 extern void VP8EncDspInitNEON(void);
    739 extern void VP8EncDspInitMIPS32(void);
    740 extern void VP8EncDspInitMIPSdspR2(void);
    741 extern void VP8EncDspInitMSA(void);
    742 
    743 static volatile VP8CPUInfo enc_last_cpuinfo_used =
    744     (VP8CPUInfo)&enc_last_cpuinfo_used;
    745 
    746 WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspInit(void) {
    747   if (enc_last_cpuinfo_used == VP8GetCPUInfo) return;
    748 
    749   VP8DspInit();  // common inverse transforms
    750   InitTables();
    751 
    752   // default C implementations
    753 #if !WEBP_NEON_OMIT_C_CODE
    754   VP8ITransform = ITransform_C;
    755   VP8FTransform = FTransform_C;
    756   VP8FTransformWHT = FTransformWHT_C;
    757   VP8TDisto4x4 = Disto4x4_C;
    758   VP8TDisto16x16 = Disto16x16_C;
    759   VP8CollectHistogram = CollectHistogram_C;
    760   VP8SSE16x16 = SSE16x16_C;
    761   VP8SSE16x8 = SSE16x8_C;
    762   VP8SSE8x8 = SSE8x8_C;
    763   VP8SSE4x4 = SSE4x4_C;
    764 #endif
    765 
    766 #if !WEBP_NEON_OMIT_C_CODE || WEBP_NEON_WORK_AROUND_GCC
    767   VP8EncQuantizeBlock = QuantizeBlock_C;
    768   VP8EncQuantize2Blocks = Quantize2Blocks_C;
    769 #endif
    770 
    771   VP8FTransform2 = FTransform2_C;
    772   VP8EncPredLuma4 = Intra4Preds_C;
    773   VP8EncPredLuma16 = Intra16Preds_C;
    774   VP8EncPredChroma8 = IntraChromaPreds_C;
    775   VP8Mean16x4 = Mean16x4_C;
    776   VP8EncQuantizeBlockWHT = QuantizeBlock_C;
    777   VP8Copy4x4 = Copy4x4_C;
    778   VP8Copy16x8 = Copy16x8_C;
    779 
    780   // If defined, use CPUInfo() to overwrite some pointers with faster versions.
    781   if (VP8GetCPUInfo != NULL) {
    782 #if defined(WEBP_USE_SSE2)
    783     if (VP8GetCPUInfo(kSSE2)) {
    784       VP8EncDspInitSSE2();
    785 #if defined(WEBP_USE_SSE41)
    786       if (VP8GetCPUInfo(kSSE4_1)) {
    787         VP8EncDspInitSSE41();
    788       }
    789 #endif
    790     }
    791 #endif
    792 #if defined(WEBP_USE_AVX2)
    793     if (VP8GetCPUInfo(kAVX2)) {
    794       VP8EncDspInitAVX2();
    795     }
    796 #endif
    797 #if defined(WEBP_USE_MIPS32)
    798     if (VP8GetCPUInfo(kMIPS32)) {
    799       VP8EncDspInitMIPS32();
    800     }
    801 #endif
    802 #if defined(WEBP_USE_MIPS_DSP_R2)
    803     if (VP8GetCPUInfo(kMIPSdspR2)) {
    804       VP8EncDspInitMIPSdspR2();
    805     }
    806 #endif
    807 #if defined(WEBP_USE_MSA)
    808     if (VP8GetCPUInfo(kMSA)) {
    809       VP8EncDspInitMSA();
    810     }
    811 #endif
    812   }
    813 
    814 #if defined(WEBP_USE_NEON)
    815   if (WEBP_NEON_OMIT_C_CODE ||
    816       (VP8GetCPUInfo != NULL && VP8GetCPUInfo(kNEON))) {
    817     VP8EncDspInitNEON();
    818   }
    819 #endif
    820 
    821   assert(VP8ITransform != NULL);
    822   assert(VP8FTransform != NULL);
    823   assert(VP8FTransformWHT != NULL);
    824   assert(VP8TDisto4x4 != NULL);
    825   assert(VP8TDisto16x16 != NULL);
    826   assert(VP8CollectHistogram != NULL);
    827   assert(VP8SSE16x16 != NULL);
    828   assert(VP8SSE16x8 != NULL);
    829   assert(VP8SSE8x8 != NULL);
    830   assert(VP8SSE4x4 != NULL);
    831   assert(VP8EncQuantizeBlock != NULL);
    832   assert(VP8EncQuantize2Blocks != NULL);
    833   assert(VP8FTransform2 != NULL);
    834   assert(VP8EncPredLuma4 != NULL);
    835   assert(VP8EncPredLuma16 != NULL);
    836   assert(VP8EncPredChroma8 != NULL);
    837   assert(VP8Mean16x4 != NULL);
    838   assert(VP8EncQuantizeBlockWHT != NULL);
    839   assert(VP8Copy4x4 != NULL);
    840   assert(VP8Copy16x8 != NULL);
    841 
    842   enc_last_cpuinfo_used = VP8GetCPUInfo;
    843 }
    844