third_party/libwebp/dsp/enc.c

   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@gmail.com)
  13
  14 #include <assert.h>
  15 #include <stdlib.h>  // for abs()
  16
  17 #include "./dsp.h"
  18 #include "../enc/vp8enci.h"
  19
  20 static WEBP_INLINE uint8_t clip_8b(int v) {
  21   return (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
  22 }
  23
  24 static WEBP_INLINE int clip_max(int v, int max) {
  25   return (v > max) ? max : v;
  26 }
  27
  28 //------------------------------------------------------------------------------
  29 // Compute susceptibility based on DCT-coeff histograms:
  30 // the higher, the "easier" the macroblock is to compress.
  31
  32 const int VP8DspScan[16 + 4 + 4] = {
  33   // Luma
  34   0 +  0 * BPS,  4 +  0 * BPS, 8 +  0 * BPS, 12 +  0 * BPS,
  35   0 +  4 * BPS,  4 +  4 * BPS, 8 +  4 * BPS, 12 +  4 * BPS,
  36   0 +  8 * BPS,  4 +  8 * BPS, 8 +  8 * BPS, 12 +  8 * BPS,
  37   0 + 12 * BPS,  4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS,
  38
  39   0 + 0 * BPS,   4 + 0 * BPS, 0 + 4 * BPS,  4 + 4 * BPS,    // U
  40   8 + 0 * BPS,  12 + 0 * BPS, 8 + 4 * BPS, 12 + 4 * BPS     // V
  41 };
  42
  43 static void CollectHistogram(const uint8_t* ref, const uint8_t* pred,
  44                              int start_block, int end_block,
  45                              VP8Histogram* const histo) {
  46   int j;
  47   for (j = start_block; j < end_block; ++j) {
  48     int k;
  49     int16_t out[16];
  50
  51     VP8FTransform(ref + VP8DspScan[j], pred + VP8DspScan[j], out);
  52
  53     // Convert coefficients to bin.
  54     for (k = 0; k < 16; ++k) {
  55       const int v = abs(out[k]) >> 3;  // TODO(skal): add rounding?
  56       const int clipped_value = clip_max(v, MAX_COEFF_THRESH);
  57       histo->distribution[clipped_value]++;
  58     }
  59   }
  60 }
  61
  62 //------------------------------------------------------------------------------
  63 // run-time tables (~4k)
  64
  65 static uint8_t clip1[255 + 510 + 1];    // clips [-255,510] to [0,255]
  66
  67 // We declare this variable 'volatile' to prevent instruction reordering
  68 // and make sure it's set to true _last_ (so as to be thread-safe)
  69 static volatile int tables_ok = 0;
  70
  71 static void InitTables(void) {
  72   if (!tables_ok) {
  73     int i;
  74     for (i = -255; i <= 255 + 255; ++i) {
  75       clip1[255 + i] = clip_8b(i);
  76     }
  77     tables_ok = 1;
  78   }
  79 }
  80
  81
  82 //------------------------------------------------------------------------------
  83 // Transforms (Paragraph 14.4)
  84
  85 #define STORE(x, y, v) \
  86   dst[(x) + (y) * BPS] = clip_8b(ref[(x) + (y) * BPS] + ((v) >> 3))
  87
  88 static const int kC1 = 20091 + (1 << 16);
  89 static const int kC2 = 35468;
  90 #define MUL(a, b) (((a) * (b)) >> 16)
  91
  92 static WEBP_INLINE void ITransformOne(const uint8_t* ref, const int16_t* in,
  93                                       uint8_t* dst) {
  94   int C[4 * 4], *tmp;
  95   int i;
  96   tmp = C;
  97   for (i = 0; i < 4; ++i) {    // vertical pass
  98     const int a = in[0] + in[8];
  99     const int b = in[0] - in[8];
 100     const int c = MUL(in[4], kC2) - MUL(in[12], kC1);
 101     const int d = MUL(in[4], kC1) + MUL(in[12], kC2);
 102     tmp[0] = a + d;
 103     tmp[1] = b + c;
 104     tmp[2] = b - c;
 105     tmp[3] = a - d;
 106     tmp += 4;
 107     in++;
 108   }
 109
 110   tmp = C;
 111   for (i = 0; i < 4; ++i) {    // horizontal pass
 112     const int dc = tmp[0] + 4;
 113     const int a =  dc +  tmp[8];
 114     const int b =  dc -  tmp[8];
 115     const int c = MUL(tmp[4], kC2) - MUL(tmp[12], kC1);
 116     const int d = MUL(tmp[4], kC1) + MUL(tmp[12], kC2);
 117     STORE(0, i, a + d);
 118     STORE(1, i, b + c);
 119     STORE(2, i, b - c);
 120     STORE(3, i, a - d);
 121     tmp++;
 122   }
 123 }
 124
 125 static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst,
 126                        int do_two) {
 127   ITransformOne(ref, in, dst);
 128   if (do_two) {
 129     ITransformOne(ref + 4, in + 16, dst + 4);
 130   }
 131 }
 132
 133 static void FTransform(const uint8_t* src, const uint8_t* ref, int16_t* out) {
 134   int i;
 135   int tmp[16];
 136   for (i = 0; i < 4; ++i, src += BPS, ref += BPS) {
 137     const int d0 = src[0] - ref[0];   // 9bit dynamic range ([-255,255])
 138     const int d1 = src[1] - ref[1];
 139     const int d2 = src[2] - ref[2];
 140     const int d3 = src[3] - ref[3];
 141     const int a0 = (d0 + d3);         // 10b                      [-510,510]
 142     const int a1 = (d1 + d2);
 143     const int a2 = (d1 - d2);
 144     const int a3 = (d0 - d3);
 145     tmp[0 + i * 4] = (a0 + a1) * 8;   // 14b                      [-8160,8160]
 146     tmp[1 + i * 4] = (a2 * 2217 + a3 * 5352 + 1812) >> 9;      // [-7536,7542]
 147     tmp[2 + i * 4] = (a0 - a1) * 8;
 148     tmp[3 + i * 4] = (a3 * 2217 - a2 * 5352 +  937) >> 9;
 149   }
 150   for (i = 0; i < 4; ++i) {
 151     const int a0 = (tmp[0 + i] + tmp[12 + i]);  // 15b
 152     const int a1 = (tmp[4 + i] + tmp[ 8 + i]);
 153     const int a2 = (tmp[4 + i] - tmp[ 8 + i]);
 154     const int a3 = (tmp[0 + i] - tmp[12 + i]);
 155     out[0 + i] = (a0 + a1 + 7) >> 4;            // 12b
 156     out[4 + i] = ((a2 * 2217 + a3 * 5352 + 12000) >> 16) + (a3 != 0);
 157     out[8 + i] = (a0 - a1 + 7) >> 4;
 158     out[12+ i] = ((a3 * 2217 - a2 * 5352 + 51000) >> 16);
 159   }
 160 }
 161
 162 static void FTransformWHT(const int16_t* in, int16_t* out) {
 163   // input is 12b signed
 164   int32_t tmp[16];
 165   int i;
 166   for (i = 0; i < 4; ++i, in += 64) {
 167     const int a0 = (in[0 * 16] + in[2 * 16]);  // 13b
 168     const int a1 = (in[1 * 16] + in[3 * 16]);
 169     const int a2 = (in[1 * 16] - in[3 * 16]);
 170     const int a3 = (in[0 * 16] - in[2 * 16]);
 171     tmp[0 + i * 4] = a0 + a1;   // 14b
 172     tmp[1 + i * 4] = a3 + a2;
 173     tmp[2 + i * 4] = a3 - a2;
 174     tmp[3 + i * 4] = a0 - a1;
 175   }
 176   for (i = 0; i < 4; ++i) {
 177     const int a0 = (tmp[0 + i] + tmp[8 + i]);  // 15b
 178     const int a1 = (tmp[4 + i] + tmp[12+ i]);
 179     const int a2 = (tmp[4 + i] - tmp[12+ i]);
 180     const int a3 = (tmp[0 + i] - tmp[8 + i]);
 181     const int b0 = a0 + a1;    // 16b
 182     const int b1 = a3 + a2;
 183     const int b2 = a3 - a2;
 184     const int b3 = a0 - a1;
 185     out[ 0 + i] = b0 >> 1;     // 15b
 186     out[ 4 + i] = b1 >> 1;
 187     out[ 8 + i] = b2 >> 1;
 188     out[12 + i] = b3 >> 1;
 189   }
 190 }
 191
 192 #undef MUL
 193 #undef STORE
 194
 195 //------------------------------------------------------------------------------
 196 // Intra predictions
 197
 198 #define DST(x, y) dst[(x) + (y) * BPS]
 199
 200 static WEBP_INLINE void Fill(uint8_t* dst, int value, int size) {
 201   int j;
 202   for (j = 0; j < size; ++j) {
 203     memset(dst + j * BPS, value, size);
 204   }
 205 }
 206
 207 static WEBP_INLINE void VerticalPred(uint8_t* dst,
 208                                      const uint8_t* top, int size) {
 209   int j;
 210   if (top) {
 211     for (j = 0; j < size; ++j) memcpy(dst + j * BPS, top, size);
 212   } else {
 213     Fill(dst, 127, size);
 214   }
 215 }
 216
 217 static WEBP_INLINE void HorizontalPred(uint8_t* dst,
 218                                        const uint8_t* left, int size) {
 219   if (left) {
 220     int j;
 221     for (j = 0; j < size; ++j) {
 222       memset(dst + j * BPS, left[j], size);
 223     }
 224   } else {
 225     Fill(dst, 129, size);
 226   }
 227 }
 228
 229 static WEBP_INLINE void TrueMotion(uint8_t* dst, const uint8_t* left,
 230                                    const uint8_t* top, int size) {
 231   int y;
 232   if (left) {
 233     if (top) {
 234       const uint8_t* const clip = clip1 + 255 - left[-1];
 235       for (y = 0; y < size; ++y) {
 236         const uint8_t* const clip_table = clip + left[y];
 237         int x;
 238         for (x = 0; x < size; ++x) {
 239           dst[x] = clip_table[top[x]];
 240         }
 241         dst += BPS;
 242       }
 243     } else {
 244       HorizontalPred(dst, left, size);
 245     }
 246   } else {
 247     // true motion without left samples (hence: with default 129 value)
 248     // is equivalent to VE prediction where you just copy the top samples.
 249     // Note that if top samples are not available, the default value is
 250     // then 129, and not 127 as in the VerticalPred case.
 251     if (top) {
 252       VerticalPred(dst, top, size);
 253     } else {
 254       Fill(dst, 129, size);
 255     }
 256   }
 257 }
 258
 259 static WEBP_INLINE void DCMode(uint8_t* dst, const uint8_t* left,
 260                                const uint8_t* top,
 261                                int size, int round, int shift) {
 262   int DC = 0;
 263   int j;
 264   if (top) {
 265     for (j = 0; j < size; ++j) DC += top[j];
 266     if (left) {   // top and left present
 267       for (j = 0; j < size; ++j) DC += left[j];
 268     } else {      // top, but no left
 269       DC += DC;
 270     }
 271     DC = (DC + round) >> shift;
 272   } else if (left) {   // left but no top
 273     for (j = 0; j < size; ++j) DC += left[j];
 274     DC += DC;
 275     DC = (DC + round) >> shift;
 276   } else {   // no top, no left, nothing.
 277     DC = 0x80;
 278   }
 279   Fill(dst, DC, size);
 280 }
 281
 282 //------------------------------------------------------------------------------
 283 // Chroma 8x8 prediction (paragraph 12.2)
 284
 285 static void IntraChromaPreds(uint8_t* dst, const uint8_t* left,
 286                              const uint8_t* top) {
 287   // U block
 288   DCMode(C8DC8 + dst, left, top, 8, 8, 4);
 289   VerticalPred(C8VE8 + dst, top, 8);
 290   HorizontalPred(C8HE8 + dst, left, 8);
 291   TrueMotion(C8TM8 + dst, left, top, 8);
 292   // V block
 293   dst += 8;
 294   if (top) top += 8;
 295   if (left) left += 16;
 296   DCMode(C8DC8 + dst, left, top, 8, 8, 4);
 297   VerticalPred(C8VE8 + dst, top, 8);
 298   HorizontalPred(C8HE8 + dst, left, 8);
 299   TrueMotion(C8TM8 + dst, left, top, 8);
 300 }
 301
 302 //------------------------------------------------------------------------------
 303 // luma 16x16 prediction (paragraph 12.3)
 304
 305 static void Intra16Preds(uint8_t* dst,
 306                          const uint8_t* left, const uint8_t* top) {
 307   DCMode(I16DC16 + dst, left, top, 16, 16, 5);
 308   VerticalPred(I16VE16 + dst, top, 16);
 309   HorizontalPred(I16HE16 + dst, left, 16);
 310   TrueMotion(I16TM16 + dst, left, top, 16);
 311 }
 312
 313 //------------------------------------------------------------------------------
 314 // luma 4x4 prediction
 315
 316 #define AVG3(a, b, c) (((a) + 2 * (b) + (c) + 2) >> 2)
 317 #define AVG2(a, b) (((a) + (b) + 1) >> 1)
 318
 319 static void VE4(uint8_t* dst, const uint8_t* top) {    // vertical
 320   const uint8_t vals[4] = {
 321     AVG3(top[-1], top[0], top[1]),
 322     AVG3(top[ 0], top[1], top[2]),
 323     AVG3(top[ 1], top[2], top[3]),
 324     AVG3(top[ 2], top[3], top[4])
 325   };
 326   int i;
 327   for (i = 0; i < 4; ++i) {
 328     memcpy(dst + i * BPS, vals, 4);
 329   }
 330 }
 331
 332 static void HE4(uint8_t* dst, const uint8_t* top) {    // horizontal
 333   const int X = top[-1];
 334   const int I = top[-2];
 335   const int J = top[-3];
 336   const int K = top[-4];
 337   const int L = top[-5];
 338   *(uint32_t*)(dst + 0 * BPS) = 0x01010101U * AVG3(X, I, J);
 339   *(uint32_t*)(dst + 1 * BPS) = 0x01010101U * AVG3(I, J, K);
 340   *(uint32_t*)(dst + 2 * BPS) = 0x01010101U * AVG3(J, K, L);
 341   *(uint32_t*)(dst + 3 * BPS) = 0x01010101U * AVG3(K, L, L);
 342 }
 343
 344 static void DC4(uint8_t* dst, const uint8_t* top) {
 345   uint32_t dc = 4;
 346   int i;
 347   for (i = 0; i < 4; ++i) dc += top[i] + top[-5 + i];
 348   Fill(dst, dc >> 3, 4);
 349 }
 350
 351 static void RD4(uint8_t* dst, const uint8_t* top) {
 352   const int X = top[-1];
 353   const int I = top[-2];
 354   const int J = top[-3];
 355   const int K = top[-4];
 356   const int L = top[-5];
 357   const int A = top[0];
 358   const int B = top[1];
 359   const int C = top[2];
 360   const int D = top[3];
 361   DST(0, 3)                                     = AVG3(J, K, L);
 362   DST(0, 2) = DST(1, 3)                         = AVG3(I, J, K);
 363   DST(0, 1) = DST(1, 2) = DST(2, 3)             = AVG3(X, I, J);
 364   DST(0, 0) = DST(1, 1) = DST(2, 2) = DST(3, 3) = AVG3(A, X, I);
 365   DST(1, 0) = DST(2, 1) = DST(3, 2)             = AVG3(B, A, X);
 366   DST(2, 0) = DST(3, 1)                         = AVG3(C, B, A);
 367   DST(3, 0)                                     = AVG3(D, C, B);
 368 }
 369
 370 static void LD4(uint8_t* dst, const uint8_t* top) {
 371   const int A = top[0];
 372   const int B = top[1];
 373   const int C = top[2];
 374   const int D = top[3];
 375   const int E = top[4];
 376   const int F = top[5];
 377   const int G = top[6];
 378   const int H = top[7];
 379   DST(0, 0)                                     = AVG3(A, B, C);
 380   DST(1, 0) = DST(0, 1)                         = AVG3(B, C, D);
 381   DST(2, 0) = DST(1, 1) = DST(0, 2)             = AVG3(C, D, E);
 382   DST(3, 0) = DST(2, 1) = DST(1, 2) = DST(0, 3) = AVG3(D, E, F);
 383   DST(3, 1) = DST(2, 2) = DST(1, 3)             = AVG3(E, F, G);
 384   DST(3, 2) = DST(2, 3)                         = AVG3(F, G, H);
 385   DST(3, 3)                                     = AVG3(G, H, H);
 386 }
 387
 388 static void VR4(uint8_t* dst, const uint8_t* top) {
 389   const int X = top[-1];
 390   const int I = top[-2];
 391   const int J = top[-3];
 392   const int K = top[-4];
 393   const int A = top[0];
 394   const int B = top[1];
 395   const int C = top[2];
 396   const int D = top[3];
 397   DST(0, 0) = DST(1, 2) = AVG2(X, A);
 398   DST(1, 0) = DST(2, 2) = AVG2(A, B);
 399   DST(2, 0) = DST(3, 2) = AVG2(B, C);
 400   DST(3, 0)             = AVG2(C, D);
 401
 402   DST(0, 3) =             AVG3(K, J, I);
 403   DST(0, 2) =             AVG3(J, I, X);
 404   DST(0, 1) = DST(1, 3) = AVG3(I, X, A);
 405   DST(1, 1) = DST(2, 3) = AVG3(X, A, B);
 406   DST(2, 1) = DST(3, 3) = AVG3(A, B, C);
 407   DST(3, 1) =             AVG3(B, C, D);
 408 }
 409
 410 static void VL4(uint8_t* dst, const uint8_t* top) {
 411   const int A = top[0];
 412   const int B = top[1];
 413   const int C = top[2];
 414   const int D = top[3];
 415   const int E = top[4];
 416   const int F = top[5];
 417   const int G = top[6];
 418   const int H = top[7];
 419   DST(0, 0) =             AVG2(A, B);
 420   DST(1, 0) = DST(0, 2) = AVG2(B, C);
 421   DST(2, 0) = DST(1, 2) = AVG2(C, D);
 422   DST(3, 0) = DST(2, 2) = AVG2(D, E);
 423
 424   DST(0, 1) =             AVG3(A, B, C);
 425   DST(1, 1) = DST(0, 3) = AVG3(B, C, D);
 426   DST(2, 1) = DST(1, 3) = AVG3(C, D, E);
 427   DST(3, 1) = DST(2, 3) = AVG3(D, E, F);
 428               DST(3, 2) = AVG3(E, F, G);
 429               DST(3, 3) = AVG3(F, G, H);
 430 }
 431
 432 static void HU4(uint8_t* dst, const uint8_t* top) {
 433   const int I = top[-2];
 434   const int J = top[-3];
 435   const int K = top[-4];
 436   const int L = top[-5];
 437   DST(0, 0) =             AVG2(I, J);
 438   DST(2, 0) = DST(0, 1) = AVG2(J, K);
 439   DST(2, 1) = DST(0, 2) = AVG2(K, L);
 440   DST(1, 0) =             AVG3(I, J, K);
 441   DST(3, 0) = DST(1, 1) = AVG3(J, K, L);
 442   DST(3, 1) = DST(1, 2) = AVG3(K, L, L);
 443   DST(3, 2) = DST(2, 2) =
 444   DST(0, 3) = DST(1, 3) = DST(2, 3) = DST(3, 3) = L;
 445 }
 446
 447 static void HD4(uint8_t* dst, const uint8_t* top) {
 448   const int X = top[-1];
 449   const int I = top[-2];
 450   const int J = top[-3];
 451   const int K = top[-4];
 452   const int L = top[-5];
 453   const int A = top[0];
 454   const int B = top[1];
 455   const int C = top[2];
 456
 457   DST(0, 0) = DST(2, 1) = AVG2(I, X);
 458   DST(0, 1) = DST(2, 2) = AVG2(J, I);
 459   DST(0, 2) = DST(2, 3) = AVG2(K, J);
 460   DST(0, 3)             = AVG2(L, K);
 461
 462   DST(3, 0)             = AVG3(A, B, C);
 463   DST(2, 0)             = AVG3(X, A, B);
 464   DST(1, 0) = DST(3, 1) = AVG3(I, X, A);
 465   DST(1, 1) = DST(3, 2) = AVG3(J, I, X);
 466   DST(1, 2) = DST(3, 3) = AVG3(K, J, I);
 467   DST(1, 3)             = AVG3(L, K, J);
 468 }
 469
 470 static void TM4(uint8_t* dst, const uint8_t* top) {
 471   int x, y;
 472   const uint8_t* const clip = clip1 + 255 - top[-1];
 473   for (y = 0; y < 4; ++y) {
 474     const uint8_t* const clip_table = clip + top[-2 - y];
 475     for (x = 0; x < 4; ++x) {
 476       dst[x] = clip_table[top[x]];
 477     }
 478     dst += BPS;
 479   }
 480 }
 481
 482 #undef DST
 483 #undef AVG3
 484 #undef AVG2
 485
 486 // Left samples are top[-5 .. -2], top_left is top[-1], top are
 487 // located at top[0..3], and top right is top[4..7]
 488 static void Intra4Preds(uint8_t* dst, const uint8_t* top) {
 489   DC4(I4DC4 + dst, top);
 490   TM4(I4TM4 + dst, top);
 491   VE4(I4VE4 + dst, top);
 492   HE4(I4HE4 + dst, top);
 493   RD4(I4RD4 + dst, top);
 494   VR4(I4VR4 + dst, top);
 495   LD4(I4LD4 + dst, top);
 496   VL4(I4VL4 + dst, top);
 497   HD4(I4HD4 + dst, top);
 498   HU4(I4HU4 + dst, top);
 499 }
 500
 501 //------------------------------------------------------------------------------
 502 // Metric
 503
 504 static WEBP_INLINE int GetSSE(const uint8_t* a, const uint8_t* b,
 505                               int w, int h) {
 506   int count = 0;
 507   int y, x;
 508   for (y = 0; y < h; ++y) {
 509     for (x = 0; x < w; ++x) {
 510       const int diff = (int)a[x] - b[x];
 511       count += diff * diff;
 512     }
 513     a += BPS;
 514     b += BPS;
 515   }
 516   return count;
 517 }
 518
 519 static int SSE16x16(const uint8_t* a, const uint8_t* b) {
 520   return GetSSE(a, b, 16, 16);
 521 }
 522 static int SSE16x8(const uint8_t* a, const uint8_t* b) {
 523   return GetSSE(a, b, 16, 8);
 524 }
 525 static int SSE8x8(const uint8_t* a, const uint8_t* b) {
 526   return GetSSE(a, b, 8, 8);
 527 }
 528 static int SSE4x4(const uint8_t* a, const uint8_t* b) {
 529   return GetSSE(a, b, 4, 4);
 530 }
 531
 532 //------------------------------------------------------------------------------
 533 // Texture distortion
 534 //
 535 // We try to match the spectral content (weighted) between source and
 536 // reconstructed samples.
 537
 538 // Hadamard transform
 539 // Returns the weighted sum of the absolute value of transformed coefficients.
 540 static int TTransform(const uint8_t* in, const uint16_t* w) {
 541   int sum = 0;
 542   int tmp[16];
 543   int i;
 544   // horizontal pass
 545   for (i = 0; i < 4; ++i, in += BPS) {
 546     const int a0 = in[0] + in[2];
 547     const int a1 = in[1] + in[3];
 548     const int a2 = in[1] - in[3];
 549     const int a3 = in[0] - in[2];
 550     tmp[0 + i * 4] = a0 + a1;
 551     tmp[1 + i * 4] = a3 + a2;
 552     tmp[2 + i * 4] = a3 - a2;
 553     tmp[3 + i * 4] = a0 - a1;
 554   }
 555   // vertical pass
 556   for (i = 0; i < 4; ++i, ++w) {
 557     const int a0 = tmp[0 + i] + tmp[8 + i];
 558     const int a1 = tmp[4 + i] + tmp[12+ i];
 559     const int a2 = tmp[4 + i] - tmp[12+ i];
 560     const int a3 = tmp[0 + i] - tmp[8 + i];
 561     const int b0 = a0 + a1;
 562     const int b1 = a3 + a2;
 563     const int b2 = a3 - a2;
 564     const int b3 = a0 - a1;
 565
 566     sum += w[ 0] * abs(b0);
 567     sum += w[ 4] * abs(b1);
 568     sum += w[ 8] * abs(b2);
 569     sum += w[12] * abs(b3);
 570   }
 571   return sum;
 572 }
 573
 574 static int Disto4x4(const uint8_t* const a, const uint8_t* const b,
 575                     const uint16_t* const w) {
 576   const int sum1 = TTransform(a, w);
 577   const int sum2 = TTransform(b, w);
 578   return abs(sum2 - sum1) >> 5;
 579 }
 580
 581 static int Disto16x16(const uint8_t* const a, const uint8_t* const b,
 582                       const uint16_t* const w) {
 583   int D = 0;
 584   int x, y;
 585   for (y = 0; y < 16 * BPS; y += 4 * BPS) {
 586     for (x = 0; x < 16; x += 4) {
 587       D += Disto4x4(a + x + y, b + x + y, w);
 588     }
 589   }
 590   return D;
 591 }
 592
 593 //------------------------------------------------------------------------------
 594 // Quantization
 595 //
 596
 597 static const uint8_t kZigzag[16] = {
 598   0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
 599 };
 600
 601 // Simple quantization
 602 static int QuantizeBlock(int16_t in[16], int16_t out[16],
 603                          const VP8Matrix* const mtx) {
 604   int last = -1;
 605   int n;
 606   for (n = 0; n < 16; ++n) {
 607     const int j = kZigzag[n];
 608     const int sign = (in[j] < 0);
 609     const uint32_t coeff = (sign ? -in[j] : in[j]) + mtx->sharpen_[j];
 610     if (coeff > mtx->zthresh_[j]) {
 611       const uint32_t Q = mtx->q_[j];
 612       const uint32_t iQ = mtx->iq_[j];
 613       const uint32_t B = mtx->bias_[j];
 614       int level = QUANTDIV(coeff, iQ, B);
 615       if (level > MAX_LEVEL) level = MAX_LEVEL;
 616       if (sign) level = -level;
 617       in[j] = level * Q;
 618       out[n] = level;
 619       if (level) last = n;
 620     } else {
 621       out[n] = 0;
 622       in[j] = 0;
 623     }
 624   }
 625   return (last >= 0);
 626 }
 627
 628 static int QuantizeBlockWHT(int16_t in[16], int16_t out[16],
 629                             const VP8Matrix* const mtx) {
 630   int n, last = -1;
 631   for (n = 0; n < 16; ++n) {
 632     const int j = kZigzag[n];
 633     const int sign = (in[j] < 0);
 634     const uint32_t coeff = sign ? -in[j] : in[j];
 635     assert(mtx->sharpen_[j] == 0);
 636     if (coeff > mtx->zthresh_[j]) {
 637       const uint32_t Q = mtx->q_[j];
 638       const uint32_t iQ = mtx->iq_[j];
 639       const uint32_t B = mtx->bias_[j];
 640       int level = QUANTDIV(coeff, iQ, B);
 641       if (level > MAX_LEVEL) level = MAX_LEVEL;
 642       if (sign) level = -level;
 643       in[j] = level * Q;
 644       out[n] = level;
 645       if (level) last = n;
 646     } else {
 647       out[n] = 0;
 648       in[j] = 0;
 649     }
 650   }
 651   return (last >= 0);
 652 }
 653
 654 //------------------------------------------------------------------------------
 655 // Block copy
 656
 657 static WEBP_INLINE void Copy(const uint8_t* src, uint8_t* dst, int size) {
 658   int y;
 659   for (y = 0; y < size; ++y) {
 660     memcpy(dst, src, size);
 661     src += BPS;
 662     dst += BPS;
 663   }
 664 }
 665
 666 static void Copy4x4(const uint8_t* src, uint8_t* dst) { Copy(src, dst, 4); }
 667
 668 //------------------------------------------------------------------------------
 669 // Initialization
 670
 671 // Speed-critical function pointers. We have to initialize them to the default
 672 // implementations within VP8EncDspInit().
 673 VP8CHisto VP8CollectHistogram;
 674 VP8Idct VP8ITransform;
 675 VP8Fdct VP8FTransform;
 676 VP8WHT VP8FTransformWHT;
 677 VP8Intra4Preds VP8EncPredLuma4;
 678 VP8IntraPreds VP8EncPredLuma16;
 679 VP8IntraPreds VP8EncPredChroma8;
 680 VP8Metric VP8SSE16x16;
 681 VP8Metric VP8SSE8x8;
 682 VP8Metric VP8SSE16x8;
 683 VP8Metric VP8SSE4x4;
 684 VP8WMetric VP8TDisto4x4;
 685 VP8WMetric VP8TDisto16x16;
 686 VP8QuantizeBlock VP8EncQuantizeBlock;
 687 VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
 688 VP8BlockCopy VP8Copy4x4;
 689
 690 extern void VP8EncDspInitSSE2(void);
 691 extern void VP8EncDspInitAVX2(void);
 692 extern void VP8EncDspInitNEON(void);
 693 extern void VP8EncDspInitMIPS32(void);
 694
 695 static volatile VP8CPUInfo enc_last_cpuinfo_used =
 696     (VP8CPUInfo)&enc_last_cpuinfo_used;
 697
 698 void VP8EncDspInit(void) {
 699   if (enc_last_cpuinfo_used == VP8GetCPUInfo) return;
 700
 701   VP8DspInit();  // common inverse transforms
 702   InitTables();
 703
 704   // default C implementations
 705   VP8CollectHistogram = CollectHistogram;
 706   VP8ITransform = ITransform;
 707   VP8FTransform = FTransform;
 708   VP8FTransformWHT = FTransformWHT;
 709   VP8EncPredLuma4 = Intra4Preds;
 710   VP8EncPredLuma16 = Intra16Preds;
 711   VP8EncPredChroma8 = IntraChromaPreds;
 712   VP8SSE16x16 = SSE16x16;
 713   VP8SSE8x8 = SSE8x8;
 714   VP8SSE16x8 = SSE16x8;
 715   VP8SSE4x4 = SSE4x4;
 716   VP8TDisto4x4 = Disto4x4;
 717   VP8TDisto16x16 = Disto16x16;
 718   VP8EncQuantizeBlock = QuantizeBlock;
 719   VP8EncQuantizeBlockWHT = QuantizeBlockWHT;
 720   VP8Copy4x4 = Copy4x4;
 721
 722   // If defined, use CPUInfo() to overwrite some pointers with faster versions.
 723   if (VP8GetCPUInfo != NULL) {
 724 #if defined(WEBP_USE_SSE2)
 725     if (VP8GetCPUInfo(kSSE2)) {
 726       VP8EncDspInitSSE2();
 727     }
 728 #endif
 729 #if defined(WEBP_USE_AVX2)
 730     if (VP8GetCPUInfo(kAVX2)) {
 731       VP8EncDspInitAVX2();
 732     }
 733 #endif
 734 #if defined(WEBP_USE_NEON)
 735     if (VP8GetCPUInfo(kNEON)) {
 736       VP8EncDspInitNEON();
 737     }
 738 #endif
 739 #if defined(WEBP_USE_MIPS32)
 740     if (VP8GetCPUInfo(kMIPS32)) {
 741       VP8EncDspInitMIPS32();
 742     }
 743 #endif
 744   }
 745   enc_last_cpuinfo_used = VP8GetCPUInfo;
 746 }
 747