third_party/libwebp/dsp/enc.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
clip_8b
clip_max
CollectHistogram
InitTables
ITransformOne
ITransform
FTransform
ITransformWHT
FTransformWHT
Fill
VerticalPred
HorizontalPred
TrueMotion
DCMode
IntraChromaPreds
Intra16Preds
VE4
HE4
DC4
RD4
LD4
VR4
VL4
HU4
HD4
TM4
Intra4Preds
GetSSE
SSE16x16
SSE16x8
SSE8x8
SSE4x4
TTransform
Disto4x4
Disto16x16
QuantizeBlock
QuantizeBlockWHT
Copy
Copy4x4
VP8EncDspInit
// Copyright 2011 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Speed-critical encoding functions.
//
// Author: Skal (pascal.massimino@gmail.com)

#include <assert.h>
#include <stdlib.h>  // for abs()

#include "./dsp.h"
#include "../enc/vp8enci.h"

static WEBP_INLINE uint8_t clip_8b(int v) {
  return (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
}

static WEBP_INLINE int clip_max(int v, int max) {
  return (v > max) ? max : v;
}

//------------------------------------------------------------------------------
// Compute susceptibility based on DCT-coeff histograms:
// the higher, the "easier" the macroblock is to compress.

const int VP8DspScan[16 + 4 + 4] = {
  // Luma
  0 +  0 * BPS,  4 +  0 * BPS, 8 +  0 * BPS, 12 +  0 * BPS,
  0 +  4 * BPS,  4 +  4 * BPS, 8 +  4 * BPS, 12 +  4 * BPS,
  0 +  8 * BPS,  4 +  8 * BPS, 8 +  8 * BPS, 12 +  8 * BPS,
  0 + 12 * BPS,  4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS,

  0 + 0 * BPS,   4 + 0 * BPS, 0 + 4 * BPS,  4 + 4 * BPS,    // U
  8 + 0 * BPS,  12 + 0 * BPS, 8 + 4 * BPS, 12 + 4 * BPS     // V
};

static void CollectHistogram(const uint8_t* ref, const uint8_t* pred,
                             int start_block, int end_block,
                             VP8Histogram* const histo) {
  int j;
  for (j = start_block; j < end_block; ++j) {
    int k;
    int16_t out[16];

    VP8FTransform(ref + VP8DspScan[j], pred + VP8DspScan[j], out);

    // Convert coefficients to bin.
    for (k = 0; k < 16; ++k) {
      const int v = abs(out[k]) >> 3;  // TODO(skal): add rounding?
      const int clipped_value = clip_max(v, MAX_COEFF_THRESH);
      histo->distribution[clipped_value]++;
    }
  }
}

//------------------------------------------------------------------------------
// run-time tables (~4k)

static uint8_t clip1[255 + 510 + 1];    // clips [-255,510] to [0,255]

// We declare this variable 'volatile' to prevent instruction reordering
// and make sure it's set to true _last_ (so as to be thread-safe)
static volatile int tables_ok = 0;

static void InitTables(void) {
  if (!tables_ok) {
    int i;
    for (i = -255; i <= 255 + 255; ++i) {
      clip1[255 + i] = clip_8b(i);
    }
    tables_ok = 1;
  }
}


//------------------------------------------------------------------------------
// Transforms (Paragraph 14.4)

#define STORE(x, y, v) \
  dst[(x) + (y) * BPS] = clip_8b(ref[(x) + (y) * BPS] + ((v) >> 3))

static const int kC1 = 20091 + (1 << 16);
static const int kC2 = 35468;
#define MUL(a, b) (((a) * (b)) >> 16)

static WEBP_INLINE void ITransformOne(const uint8_t* ref, const int16_t* in,
                                      uint8_t* dst) {
  int C[4 * 4], *tmp;
  int i;
  tmp = C;
  for (i = 0; i < 4; ++i) {    // vertical pass
    const int a = in[0] + in[8];
    const int b = in[0] - in[8];
    const int c = MUL(in[4], kC2) - MUL(in[12], kC1);
    const int d = MUL(in[4], kC1) + MUL(in[12], kC2);
    tmp[0] = a + d;
    tmp[1] = b + c;
    tmp[2] = b - c;
    tmp[3] = a - d;
    tmp += 4;
    in++;
  }

  tmp = C;
  for (i = 0; i < 4; ++i) {    // horizontal pass
    const int dc = tmp[0] + 4;
    const int a =  dc +  tmp[8];
    const int b =  dc -  tmp[8];
    const int c = MUL(tmp[4], kC2) - MUL(tmp[12], kC1);
    const int d = MUL(tmp[4], kC1) + MUL(tmp[12], kC2);
    STORE(0, i, a + d);
    STORE(1, i, b + c);
    STORE(2, i, b - c);
    STORE(3, i, a - d);
    tmp++;
  }
}

static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst,
                       int do_two) {
  ITransformOne(ref, in, dst);
  if (do_two) {
    ITransformOne(ref + 4, in + 16, dst + 4);
  }
}

static void FTransform(const uint8_t* src, const uint8_t* ref, int16_t* out) {
  int i;
  int tmp[16];
  for (i = 0; i < 4; ++i, src += BPS, ref += BPS) {
    const int d0 = src[0] - ref[0];   // 9bit dynamic range ([-255,255])
    const int d1 = src[1] - ref[1];
    const int d2 = src[2] - ref[2];
    const int d3 = src[3] - ref[3];
    const int a0 = (d0 + d3);         // 10b                      [-510,510]
    const int a1 = (d1 + d2);
    const int a2 = (d1 - d2);
    const int a3 = (d0 - d3);
    tmp[0 + i * 4] = (a0 + a1) * 8;   // 14b                      [-8160,8160]
    tmp[1 + i * 4] = (a2 * 2217 + a3 * 5352 + 1812) >> 9;      // [-7536,7542]
    tmp[2 + i * 4] = (a0 - a1) * 8;
    tmp[3 + i * 4] = (a3 * 2217 - a2 * 5352 +  937) >> 9;
  }
  for (i = 0; i < 4; ++i) {
    const int a0 = (tmp[0 + i] + tmp[12 + i]);  // 15b
    const int a1 = (tmp[4 + i] + tmp[ 8 + i]);
    const int a2 = (tmp[4 + i] - tmp[ 8 + i]);
    const int a3 = (tmp[0 + i] - tmp[12 + i]);
    out[0 + i] = (a0 + a1 + 7) >> 4;            // 12b
    out[4 + i] = ((a2 * 2217 + a3 * 5352 + 12000) >> 16) + (a3 != 0);
    out[8 + i] = (a0 - a1 + 7) >> 4;
    out[12+ i] = ((a3 * 2217 - a2 * 5352 + 51000) >> 16);
  }
}

static void ITransformWHT(const int16_t* in, int16_t* out) {
  int tmp[16];
  int i;
  for (i = 0; i < 4; ++i) {
    const int a0 = in[0 + i] + in[12 + i];
    const int a1 = in[4 + i] + in[ 8 + i];
    const int a2 = in[4 + i] - in[ 8 + i];
    const int a3 = in[0 + i] - in[12 + i];
    tmp[0  + i] = a0 + a1;
    tmp[8  + i] = a0 - a1;
    tmp[4  + i] = a3 + a2;
    tmp[12 + i] = a3 - a2;
  }
  for (i = 0; i < 4; ++i) {
    const int dc = tmp[0 + i * 4] + 3;    // w/ rounder
    const int a0 = dc             + tmp[3 + i * 4];
    const int a1 = tmp[1 + i * 4] + tmp[2 + i * 4];
    const int a2 = tmp[1 + i * 4] - tmp[2 + i * 4];
    const int a3 = dc             - tmp[3 + i * 4];
    out[ 0] = (a0 + a1) >> 3;
    out[16] = (a3 + a2) >> 3;
    out[32] = (a0 - a1) >> 3;
    out[48] = (a3 - a2) >> 3;
    out += 64;
  }
}

static void FTransformWHT(const int16_t* in, int16_t* out) {
  // input is 12b signed
  int32_t tmp[16];
  int i;
  for (i = 0; i < 4; ++i, in += 64) {
    const int a0 = (in[0 * 16] + in[2 * 16]);  // 13b
    const int a1 = (in[1 * 16] + in[3 * 16]);
    const int a2 = (in[1 * 16] - in[3 * 16]);
    const int a3 = (in[0 * 16] - in[2 * 16]);
    tmp[0 + i * 4] = a0 + a1;   // 14b
    tmp[1 + i * 4] = a3 + a2;
    tmp[2 + i * 4] = a3 - a2;
    tmp[3 + i * 4] = a0 - a1;
  }
  for (i = 0; i < 4; ++i) {
    const int a0 = (tmp[0 + i] + tmp[8 + i]);  // 15b
    const int a1 = (tmp[4 + i] + tmp[12+ i]);
    const int a2 = (tmp[4 + i] - tmp[12+ i]);
    const int a3 = (tmp[0 + i] - tmp[8 + i]);
    const int b0 = a0 + a1;    // 16b
    const int b1 = a3 + a2;
    const int b2 = a3 - a2;
    const int b3 = a0 - a1;
    out[ 0 + i] = b0 >> 1;     // 15b
    out[ 4 + i] = b1 >> 1;
    out[ 8 + i] = b2 >> 1;
    out[12 + i] = b3 >> 1;
  }
}

#undef MUL
#undef STORE

//------------------------------------------------------------------------------
// Intra predictions

#define DST(x, y) dst[(x) + (y) * BPS]

static WEBP_INLINE void Fill(uint8_t* dst, int value, int size) {
  int j;
  for (j = 0; j < size; ++j) {
    memset(dst + j * BPS, value, size);
  }
}

static WEBP_INLINE void VerticalPred(uint8_t* dst,
                                     const uint8_t* top, int size) {
  int j;
  if (top) {
    for (j = 0; j < size; ++j) memcpy(dst + j * BPS, top, size);
  } else {
    Fill(dst, 127, size);
  }
}

static WEBP_INLINE void HorizontalPred(uint8_t* dst,
                                       const uint8_t* left, int size) {
  if (left) {
    int j;
    for (j = 0; j < size; ++j) {
      memset(dst + j * BPS, left[j], size);
    }
  } else {
    Fill(dst, 129, size);
  }
}

static WEBP_INLINE void TrueMotion(uint8_t* dst, const uint8_t* left,
                                   const uint8_t* top, int size) {
  int y;
  if (left) {
    if (top) {
      const uint8_t* const clip = clip1 + 255 - left[-1];
      for (y = 0; y < size; ++y) {
        const uint8_t* const clip_table = clip + left[y];
        int x;
        for (x = 0; x < size; ++x) {
          dst[x] = clip_table[top[x]];
        }
        dst += BPS;
      }
    } else {
      HorizontalPred(dst, left, size);
    }
  } else {
    // true motion without left samples (hence: with default 129 value)
    // is equivalent to VE prediction where you just copy the top samples.
    // Note that if top samples are not available, the default value is
    // then 129, and not 127 as in the VerticalPred case.
    if (top) {
      VerticalPred(dst, top, size);
    } else {
      Fill(dst, 129, size);
    }
  }
}

static WEBP_INLINE void DCMode(uint8_t* dst, const uint8_t* left,
                               const uint8_t* top,
                               int size, int round, int shift) {
  int DC = 0;
  int j;
  if (top) {
    for (j = 0; j < size; ++j) DC += top[j];
    if (left) {   // top and left present
      for (j = 0; j < size; ++j) DC += left[j];
    } else {      // top, but no left
      DC += DC;
    }
    DC = (DC + round) >> shift;
  } else if (left) {   // left but no top
    for (j = 0; j < size; ++j) DC += left[j];
    DC += DC;
    DC = (DC + round) >> shift;
  } else {   // no top, no left, nothing.
    DC = 0x80;
  }
  Fill(dst, DC, size);
}

//------------------------------------------------------------------------------
// Chroma 8x8 prediction (paragraph 12.2)

static void IntraChromaPreds(uint8_t* dst, const uint8_t* left,
                             const uint8_t* top) {
  // U block
  DCMode(C8DC8 + dst, left, top, 8, 8, 4);
  VerticalPred(C8VE8 + dst, top, 8);
  HorizontalPred(C8HE8 + dst, left, 8);
  TrueMotion(C8TM8 + dst, left, top, 8);
  // V block
  dst += 8;
  if (top) top += 8;
  if (left) left += 16;
  DCMode(C8DC8 + dst, left, top, 8, 8, 4);
  VerticalPred(C8VE8 + dst, top, 8);
  HorizontalPred(C8HE8 + dst, left, 8);
  TrueMotion(C8TM8 + dst, left, top, 8);
}

//------------------------------------------------------------------------------
// luma 16x16 prediction (paragraph 12.3)

static void Intra16Preds(uint8_t* dst,
                         const uint8_t* left, const uint8_t* top) {
  DCMode(I16DC16 + dst, left, top, 16, 16, 5);
  VerticalPred(I16VE16 + dst, top, 16);
  HorizontalPred(I16HE16 + dst, left, 16);
  TrueMotion(I16TM16 + dst, left, top, 16);
}

//------------------------------------------------------------------------------
// luma 4x4 prediction

#define AVG3(a, b, c) (((a) + 2 * (b) + (c) + 2) >> 2)
#define AVG2(a, b) (((a) + (b) + 1) >> 1)

static void VE4(uint8_t* dst, const uint8_t* top) {    // vertical
  const uint8_t vals[4] = {
    AVG3(top[-1], top[0], top[1]),
    AVG3(top[ 0], top[1], top[2]),
    AVG3(top[ 1], top[2], top[3]),
    AVG3(top[ 2], top[3], top[4])
  };
  int i;
  for (i = 0; i < 4; ++i) {
    memcpy(dst + i * BPS, vals, 4);
  }
}

static void HE4(uint8_t* dst, const uint8_t* top) {    // horizontal
  const int X = top[-1];
  const int I = top[-2];
  const int J = top[-3];
  const int K = top[-4];
  const int L = top[-5];
  *(uint32_t*)(dst + 0 * BPS) = 0x01010101U * AVG3(X, I, J);
  *(uint32_t*)(dst + 1 * BPS) = 0x01010101U * AVG3(I, J, K);
  *(uint32_t*)(dst + 2 * BPS) = 0x01010101U * AVG3(J, K, L);
  *(uint32_t*)(dst + 3 * BPS) = 0x01010101U * AVG3(K, L, L);
}

static void DC4(uint8_t* dst, const uint8_t* top) {
  uint32_t dc = 4;
  int i;
  for (i = 0; i < 4; ++i) dc += top[i] + top[-5 + i];
  Fill(dst, dc >> 3, 4);
}

static void RD4(uint8_t* dst, const uint8_t* top) {
  const int X = top[-1];
  const int I = top[-2];
  const int J = top[-3];
  const int K = top[-4];
  const int L = top[-5];
  const int A = top[0];
  const int B = top[1];
  const int C = top[2];
  const int D = top[3];
  DST(0, 3)                                     = AVG3(J, K, L);
  DST(0, 2) = DST(1, 3)                         = AVG3(I, J, K);
  DST(0, 1) = DST(1, 2) = DST(2, 3)             = AVG3(X, I, J);
  DST(0, 0) = DST(1, 1) = DST(2, 2) = DST(3, 3) = AVG3(A, X, I);
  DST(1, 0) = DST(2, 1) = DST(3, 2)             = AVG3(B, A, X);
  DST(2, 0) = DST(3, 1)                         = AVG3(C, B, A);
  DST(3, 0)                                     = AVG3(D, C, B);
}

static void LD4(uint8_t* dst, const uint8_t* top) {
  const int A = top[0];
  const int B = top[1];
  const int C = top[2];
  const int D = top[3];
  const int E = top[4];
  const int F = top[5];
  const int G = top[6];
  const int H = top[7];
  DST(0, 0)                                     = AVG3(A, B, C);
  DST(1, 0) = DST(0, 1)                         = AVG3(B, C, D);
  DST(2, 0) = DST(1, 1) = DST(0, 2)             = AVG3(C, D, E);
  DST(3, 0) = DST(2, 1) = DST(1, 2) = DST(0, 3) = AVG3(D, E, F);
  DST(3, 1) = DST(2, 2) = DST(1, 3)             = AVG3(E, F, G);
  DST(3, 2) = DST(2, 3)                         = AVG3(F, G, H);
  DST(3, 3)                                     = AVG3(G, H, H);
}

static void VR4(uint8_t* dst, const uint8_t* top) {
  const int X = top[-1];
  const int I = top[-2];
  const int J = top[-3];
  const int K = top[-4];
  const int A = top[0];
  const int B = top[1];
  const int C = top[2];
  const int D = top[3];
  DST(0, 0) = DST(1, 2) = AVG2(X, A);
  DST(1, 0) = DST(2, 2) = AVG2(A, B);
  DST(2, 0) = DST(3, 2) = AVG2(B, C);
  DST(3, 0)             = AVG2(C, D);

  DST(0, 3) =             AVG3(K, J, I);
  DST(0, 2) =             AVG3(J, I, X);
  DST(0, 1) = DST(1, 3) = AVG3(I, X, A);
  DST(1, 1) = DST(2, 3) = AVG3(X, A, B);
  DST(2, 1) = DST(3, 3) = AVG3(A, B, C);
  DST(3, 1) =             AVG3(B, C, D);
}

static void VL4(uint8_t* dst, const uint8_t* top) {
  const int A = top[0];
  const int B = top[1];
  const int C = top[2];
  const int D = top[3];
  const int E = top[4];
  const int F = top[5];
  const int G = top[6];
  const int H = top[7];
  DST(0, 0) =             AVG2(A, B);
  DST(1, 0) = DST(0, 2) = AVG2(B, C);
  DST(2, 0) = DST(1, 2) = AVG2(C, D);
  DST(3, 0) = DST(2, 2) = AVG2(D, E);

  DST(0, 1) =             AVG3(A, B, C);
  DST(1, 1) = DST(0, 3) = AVG3(B, C, D);
  DST(2, 1) = DST(1, 3) = AVG3(C, D, E);
  DST(3, 1) = DST(2, 3) = AVG3(D, E, F);
              DST(3, 2) = AVG3(E, F, G);
              DST(3, 3) = AVG3(F, G, H);
}

static void HU4(uint8_t* dst, const uint8_t* top) {
  const int I = top[-2];
  const int J = top[-3];
  const int K = top[-4];
  const int L = top[-5];
  DST(0, 0) =             AVG2(I, J);
  DST(2, 0) = DST(0, 1) = AVG2(J, K);
  DST(2, 1) = DST(0, 2) = AVG2(K, L);
  DST(1, 0) =             AVG3(I, J, K);
  DST(3, 0) = DST(1, 1) = AVG3(J, K, L);
  DST(3, 1) = DST(1, 2) = AVG3(K, L, L);
  DST(3, 2) = DST(2, 2) =
  DST(0, 3) = DST(1, 3) = DST(2, 3) = DST(3, 3) = L;
}

static void HD4(uint8_t* dst, const uint8_t* top) {
  const int X = top[-1];
  const int I = top[-2];
  const int J = top[-3];
  const int K = top[-4];
  const int L = top[-5];
  const int A = top[0];
  const int B = top[1];
  const int C = top[2];

  DST(0, 0) = DST(2, 1) = AVG2(I, X);
  DST(0, 1) = DST(2, 2) = AVG2(J, I);
  DST(0, 2) = DST(2, 3) = AVG2(K, J);
  DST(0, 3)             = AVG2(L, K);

  DST(3, 0)             = AVG3(A, B, C);
  DST(2, 0)             = AVG3(X, A, B);
  DST(1, 0) = DST(3, 1) = AVG3(I, X, A);
  DST(1, 1) = DST(3, 2) = AVG3(J, I, X);
  DST(1, 2) = DST(3, 3) = AVG3(K, J, I);
  DST(1, 3)             = AVG3(L, K, J);
}

static void TM4(uint8_t* dst, const uint8_t* top) {
  int x, y;
  const uint8_t* const clip = clip1 + 255 - top[-1];
  for (y = 0; y < 4; ++y) {
    const uint8_t* const clip_table = clip + top[-2 - y];
    for (x = 0; x < 4; ++x) {
      dst[x] = clip_table[top[x]];
    }
    dst += BPS;
  }
}

#undef DST
#undef AVG3
#undef AVG2

// Left samples are top[-5 .. -2], top_left is top[-1], top are
// located at top[0..3], and top right is top[4..7]
static void Intra4Preds(uint8_t* dst, const uint8_t* top) {
  DC4(I4DC4 + dst, top);
  TM4(I4TM4 + dst, top);
  VE4(I4VE4 + dst, top);
  HE4(I4HE4 + dst, top);
  RD4(I4RD4 + dst, top);
  VR4(I4VR4 + dst, top);
  LD4(I4LD4 + dst, top);
  VL4(I4VL4 + dst, top);
  HD4(I4HD4 + dst, top);
  HU4(I4HU4 + dst, top);
}

//------------------------------------------------------------------------------
// Metric

static WEBP_INLINE int GetSSE(const uint8_t* a, const uint8_t* b,
                              int w, int h) {
  int count = 0;
  int y, x;
  for (y = 0; y < h; ++y) {
    for (x = 0; x < w; ++x) {
      const int diff = (int)a[x] - b[x];
      count += diff * diff;
    }
    a += BPS;
    b += BPS;
  }
  return count;
}

static int SSE16x16(const uint8_t* a, const uint8_t* b) {
  return GetSSE(a, b, 16, 16);
}
static int SSE16x8(const uint8_t* a, const uint8_t* b) {
  return GetSSE(a, b, 16, 8);
}
static int SSE8x8(const uint8_t* a, const uint8_t* b) {
  return GetSSE(a, b, 8, 8);
}
static int SSE4x4(const uint8_t* a, const uint8_t* b) {
  return GetSSE(a, b, 4, 4);
}

//------------------------------------------------------------------------------
// Texture distortion
//
// We try to match the spectral content (weighted) between source and
// reconstructed samples.

// Hadamard transform
// Returns the weighted sum of the absolute value of transformed coefficients.
static int TTransform(const uint8_t* in, const uint16_t* w) {
  int sum = 0;
  int tmp[16];
  int i;
  // horizontal pass
  for (i = 0; i < 4; ++i, in += BPS) {
    const int a0 = in[0] + in[2];
    const int a1 = in[1] + in[3];
    const int a2 = in[1] - in[3];
    const int a3 = in[0] - in[2];
    tmp[0 + i * 4] = a0 + a1;
    tmp[1 + i * 4] = a3 + a2;
    tmp[2 + i * 4] = a3 - a2;
    tmp[3 + i * 4] = a0 - a1;
  }
  // vertical pass
  for (i = 0; i < 4; ++i, ++w) {
    const int a0 = tmp[0 + i] + tmp[8 + i];
    const int a1 = tmp[4 + i] + tmp[12+ i];
    const int a2 = tmp[4 + i] - tmp[12+ i];
    const int a3 = tmp[0 + i] - tmp[8 + i];
    const int b0 = a0 + a1;
    const int b1 = a3 + a2;
    const int b2 = a3 - a2;
    const int b3 = a0 - a1;

    sum += w[ 0] * abs(b0);
    sum += w[ 4] * abs(b1);
    sum += w[ 8] * abs(b2);
    sum += w[12] * abs(b3);
  }
  return sum;
}

static int Disto4x4(const uint8_t* const a, const uint8_t* const b,
                    const uint16_t* const w) {
  const int sum1 = TTransform(a, w);
  const int sum2 = TTransform(b, w);
  return abs(sum2 - sum1) >> 5;
}

static int Disto16x16(const uint8_t* const a, const uint8_t* const b,
                      const uint16_t* const w) {
  int D = 0;
  int x, y;
  for (y = 0; y < 16 * BPS; y += 4 * BPS) {
    for (x = 0; x < 16; x += 4) {
      D += Disto4x4(a + x + y, b + x + y, w);
    }
  }
  return D;
}

//------------------------------------------------------------------------------
// Quantization
//

static const uint8_t kZigzag[16] = {
  0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
};

// Simple quantization
static int QuantizeBlock(int16_t in[16], int16_t out[16],
                         int n, const VP8Matrix* const mtx) {
  int last = -1;
  for (; n < 16; ++n) {
    const int j = kZigzag[n];
    const int sign = (in[j] < 0);
    const int coeff = (sign ? -in[j] : in[j]) + mtx->sharpen_[j];
    if (coeff > mtx->zthresh_[j]) {
      const int Q = mtx->q_[j];
      const int iQ = mtx->iq_[j];
      const int B = mtx->bias_[j];
      out[n] = QUANTDIV(coeff, iQ, B);
      if (out[n] > MAX_LEVEL) out[n] = MAX_LEVEL;
      if (sign) out[n] = -out[n];
      in[j] = out[n] * Q;
      if (out[n]) last = n;
    } else {
      out[n] = 0;
      in[j] = 0;
    }
  }
  return (last >= 0);
}

static int QuantizeBlockWHT(int16_t in[16], int16_t out[16],
                            const VP8Matrix* const mtx) {
  int n, last = -1;
  for (n = 0; n < 16; ++n) {
    const int j = kZigzag[n];
    const int sign = (in[j] < 0);
    const int coeff = sign ? -in[j] : in[j];
    assert(mtx->sharpen_[j] == 0);
    if (coeff > mtx->zthresh_[j]) {
      const int Q = mtx->q_[j];
      const int iQ = mtx->iq_[j];
      const int B = mtx->bias_[j];
      out[n] = QUANTDIV(coeff, iQ, B);
      if (out[n] > MAX_LEVEL) out[n] = MAX_LEVEL;
      if (sign) out[n] = -out[n];
      in[j] = out[n] * Q;
      if (out[n]) last = n;
    } else {
      out[n] = 0;
      in[j] = 0;
    }
  }
  return (last >= 0);
}

//------------------------------------------------------------------------------
// Block copy

static WEBP_INLINE void Copy(const uint8_t* src, uint8_t* dst, int size) {
  int y;
  for (y = 0; y < size; ++y) {
    memcpy(dst, src, size);
    src += BPS;
    dst += BPS;
  }
}

static void Copy4x4(const uint8_t* src, uint8_t* dst) { Copy(src, dst, 4); }

//------------------------------------------------------------------------------
// Initialization

// Speed-critical function pointers. We have to initialize them to the default
// implementations within VP8EncDspInit().
VP8CHisto VP8CollectHistogram;
VP8Idct VP8ITransform;
VP8Fdct VP8FTransform;
VP8WHT VP8ITransformWHT;
VP8WHT VP8FTransformWHT;
VP8Intra4Preds VP8EncPredLuma4;
VP8IntraPreds VP8EncPredLuma16;
VP8IntraPreds VP8EncPredChroma8;
VP8Metric VP8SSE16x16;
VP8Metric VP8SSE8x8;
VP8Metric VP8SSE16x8;
VP8Metric VP8SSE4x4;
VP8WMetric VP8TDisto4x4;
VP8WMetric VP8TDisto16x16;
VP8QuantizeBlock VP8EncQuantizeBlock;
VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
VP8BlockCopy VP8Copy4x4;

extern void VP8EncDspInitSSE2(void);
extern void VP8EncDspInitNEON(void);

void VP8EncDspInit(void) {
  InitTables();

  // default C implementations
  VP8CollectHistogram = CollectHistogram;
  VP8ITransform = ITransform;
  VP8FTransform = FTransform;
  VP8ITransformWHT = ITransformWHT;
  VP8FTransformWHT = FTransformWHT;
  VP8EncPredLuma4 = Intra4Preds;
  VP8EncPredLuma16 = Intra16Preds;
  VP8EncPredChroma8 = IntraChromaPreds;
  VP8SSE16x16 = SSE16x16;
  VP8SSE8x8 = SSE8x8;
  VP8SSE16x8 = SSE16x8;
  VP8SSE4x4 = SSE4x4;
  VP8TDisto4x4 = Disto4x4;
  VP8TDisto16x16 = Disto16x16;
  VP8EncQuantizeBlock = QuantizeBlock;
  VP8EncQuantizeBlockWHT = QuantizeBlockWHT;
  VP8Copy4x4 = Copy4x4;

  // If defined, use CPUInfo() to overwrite some pointers with faster versions.
  if (VP8GetCPUInfo) {
#if defined(WEBP_USE_SSE2)
    if (VP8GetCPUInfo(kSSE2)) {
      VP8EncDspInitSSE2();
    }
#elif defined(WEBP_USE_NEON)
    if (VP8GetCPUInfo(kNEON)) {
      VP8EncDspInitNEON();
    }
#endif
  }
}
/* [<][>][^][v][top][bottom][index][help] */
root/third_party/libwebp/dsp/enc.c

DEFINITIONS
