root/3rdparty/libwebp/enc/iterator.c

DEFINITIONS

1. InitLeft
2. InitTop
3. VP8IteratorReset
4. VP8IteratorInit
5. VP8IteratorProgress
6. ImportBlock
7. VP8IteratorImport
8. ExportBlock
9. VP8IteratorExport
10. VP8IteratorNzToBytes
11. VP8IteratorBytesToNz
12. VP8IteratorNext
13. VP8SetIntra16Mode
14. VP8SetIntra4Mode
15. VP8SetIntraUVMode
16. VP8SetSkip
17. VP8SetSegment
18. VP8IteratorStartI4
19. VP8IteratorRotateI4

// 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.
// -----------------------------------------------------------------------------
//
// VP8Iterator: block iterator
//
// Author: Skal (pascal.massimino@gmail.com)

#include <string.h>

#include "./vp8enci.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

//------------------------------------------------------------------------------
// VP8Iterator
//------------------------------------------------------------------------------

static void InitLeft(VP8EncIterator* const it) {
  const VP8Encoder* const enc = it->enc_;
  enc->y_left_[-1] = enc->u_left_[-1] = enc->v_left_[-1] =
      (it->y_ > 0) ? 129 : 127;
  memset(enc->y_left_, 129, 16);
  memset(enc->u_left_, 129, 8);
  memset(enc->v_left_, 129, 8);
  it->left_nz_[8] = 0;
}

static void InitTop(VP8EncIterator* const it) {
  const VP8Encoder* const enc = it->enc_;
  const size_t top_size = enc->mb_w_ * 16;
  memset(enc->y_top_, 127, 2 * top_size);
  memset(enc->nz_, 0, enc->mb_w_ * sizeof(*enc->nz_));
}

void VP8IteratorReset(VP8EncIterator* const it) {
  VP8Encoder* const enc = it->enc_;
  it->x_ = 0;
  it->y_ = 0;
  it->y_offset_ = 0;
  it->uv_offset_ = 0;
  it->mb_ = enc->mb_info_;
  it->preds_ = enc->preds_;
  it->nz_ = enc->nz_;
  it->bw_ = &enc->parts_[0];
  it->done_ = enc->mb_w_* enc->mb_h_;
  InitTop(it);
  InitLeft(it);
  memset(it->bit_count_, 0, sizeof(it->bit_count_));
  it->do_trellis_ = 0;
}

void VP8IteratorInit(VP8Encoder* const enc, VP8EncIterator* const it) {
  it->enc_ = enc;
  it->y_stride_  = enc->pic_->y_stride;
  it->uv_stride_ = enc->pic_->uv_stride;
  // TODO(later): for multithreading, these should be owned by 'it'.
  it->yuv_in_   = enc->yuv_in_;
  it->yuv_out_  = enc->yuv_out_;
  it->yuv_out2_ = enc->yuv_out2_;
  it->yuv_p_    = enc->yuv_p_;
  it->lf_stats_ = enc->lf_stats_;
  it->percent0_ = enc->percent_;
  VP8IteratorReset(it);
}

int VP8IteratorProgress(const VP8EncIterator* const it, int delta) {
  VP8Encoder* const enc = it->enc_;
  if (delta && enc->pic_->progress_hook) {
    const int percent = (enc->mb_h_ <= 1)
                      ? it->percent0_
                      : it->percent0_ + delta * it->y_ / (enc->mb_h_ - 1);
    return WebPReportProgress(enc->pic_, percent, &enc->percent_);
  }
  return 1;
}

//------------------------------------------------------------------------------
// Import the source samples into the cache. Takes care of replicating
// boundary pixels if necessary.

static void ImportBlock(const uint8_t* src, int src_stride,
                        uint8_t* dst, int w, int h, int size) {
  int i;
  for (i = 0; i < h; ++i) {
    memcpy(dst, src, w);
    if (w < size) {
      memset(dst + w, dst[w - 1], size - w);
    }
    dst += BPS;
    src += src_stride;
  }
  for (i = h; i < size; ++i) {
    memcpy(dst, dst - BPS, size);
    dst += BPS;
  }
}

void VP8IteratorImport(const VP8EncIterator* const it) {
  const VP8Encoder* const enc = it->enc_;
  const int x = it->x_, y = it->y_;
  const WebPPicture* const pic = enc->pic_;
  const uint8_t* const ysrc = pic->y + (y * pic->y_stride + x) * 16;
  const uint8_t* const usrc = pic->u + (y * pic->uv_stride + x) * 8;
  const uint8_t* const vsrc = pic->v + (y * pic->uv_stride + x) * 8;
  uint8_t* const ydst = it->yuv_in_ + Y_OFF;
  uint8_t* const udst = it->yuv_in_ + U_OFF;
  uint8_t* const vdst = it->yuv_in_ + V_OFF;
  int w = (pic->width - x * 16);
  int h = (pic->height - y * 16);

  if (w > 16) w = 16;
  if (h > 16) h = 16;

  // Luma plane
  ImportBlock(ysrc, pic->y_stride, ydst, w, h, 16);

  {   // U/V planes
    const int uv_w = (w + 1) >> 1;
    const int uv_h = (h + 1) >> 1;
    ImportBlock(usrc, pic->uv_stride, udst, uv_w, uv_h, 8);
    ImportBlock(vsrc, pic->uv_stride, vdst, uv_w, uv_h, 8);
  }
}

//------------------------------------------------------------------------------
// Copy back the compressed samples into user space if requested.

static void ExportBlock(const uint8_t* src, uint8_t* dst, int dst_stride,
                        int w, int h) {
  while (h-- > 0) {
    memcpy(dst, src, w);
    dst += dst_stride;
    src += BPS;
  }
}

void VP8IteratorExport(const VP8EncIterator* const it) {
  const VP8Encoder* const enc = it->enc_;
  if (enc->config_->show_compressed) {
    const int x = it->x_, y = it->y_;
    const uint8_t* const ysrc = it->yuv_out_ + Y_OFF;
    const uint8_t* const usrc = it->yuv_out_ + U_OFF;
    const uint8_t* const vsrc = it->yuv_out_ + V_OFF;
    const WebPPicture* const pic = enc->pic_;
    uint8_t* const ydst = pic->y + (y * pic->y_stride + x) * 16;
    uint8_t* const udst = pic->u + (y * pic->uv_stride + x) * 8;
    uint8_t* const vdst = pic->v + (y * pic->uv_stride + x) * 8;
    int w = (pic->width - x * 16);
    int h = (pic->height - y * 16);

    if (w > 16) w = 16;
    if (h > 16) h = 16;

    // Luma plane
    ExportBlock(ysrc, ydst, pic->y_stride, w, h);

    {   // U/V planes
      const int uv_w = (w + 1) >> 1;
      const int uv_h = (h + 1) >> 1;
      ExportBlock(usrc, udst, pic->uv_stride, uv_w, uv_h);
      ExportBlock(vsrc, vdst, pic->uv_stride, uv_w, uv_h);
    }
  }
}

//------------------------------------------------------------------------------
// Non-zero contexts setup/teardown

// Nz bits:
//  0  1  2  3  Y
//  4  5  6  7
//  8  9 10 11
// 12 13 14 15
// 16 17        U
// 18 19
// 20 21        V
// 22 23
// 24           DC-intra16

// Convert packed context to byte array
#define BIT(nz, n) (!!((nz) & (1 << (n))))

void VP8IteratorNzToBytes(VP8EncIterator* const it) {
  const int tnz = it->nz_[0], lnz = it->nz_[-1];
  int* const top_nz = it->top_nz_;
  int* const left_nz = it->left_nz_;

  // Top-Y
  top_nz[0] = BIT(tnz, 12);
  top_nz[1] = BIT(tnz, 13);
  top_nz[2] = BIT(tnz, 14);
  top_nz[3] = BIT(tnz, 15);
  // Top-U
  top_nz[4] = BIT(tnz, 18);
  top_nz[5] = BIT(tnz, 19);
  // Top-V
  top_nz[6] = BIT(tnz, 22);
  top_nz[7] = BIT(tnz, 23);
  // DC
  top_nz[8] = BIT(tnz, 24);

  // left-Y
  left_nz[0] = BIT(lnz,  3);
  left_nz[1] = BIT(lnz,  7);
  left_nz[2] = BIT(lnz, 11);
  left_nz[3] = BIT(lnz, 15);
  // left-U
  left_nz[4] = BIT(lnz, 17);
  left_nz[5] = BIT(lnz, 19);
  // left-V
  left_nz[6] = BIT(lnz, 21);
  left_nz[7] = BIT(lnz, 23);
  // left-DC is special, iterated separately
}

void VP8IteratorBytesToNz(VP8EncIterator* const it) {
  uint32_t nz = 0;
  const int* const top_nz = it->top_nz_;
  const int* const left_nz = it->left_nz_;
  // top
  nz |= (top_nz[0] << 12) | (top_nz[1] << 13);
  nz |= (top_nz[2] << 14) | (top_nz[3] << 15);
  nz |= (top_nz[4] << 18) | (top_nz[5] << 19);
  nz |= (top_nz[6] << 22) | (top_nz[7] << 23);
  nz |= (top_nz[8] << 24);  // we propagate the _top_ bit, esp. for intra4
  // left
  nz |= (left_nz[0] << 3) | (left_nz[1] << 7);
  nz |= (left_nz[2] << 11);
  nz |= (left_nz[4] << 17) | (left_nz[6] << 21);

  *it->nz_ = nz;
}

#undef BIT

//------------------------------------------------------------------------------
// Advance to the next position, doing the bookeeping.

int VP8IteratorNext(VP8EncIterator* const it,
                    const uint8_t* const block_to_save) {
  VP8Encoder* const enc = it->enc_;
  if (block_to_save) {
    const int x = it->x_, y = it->y_;
    const uint8_t* const ysrc = block_to_save + Y_OFF;
    const uint8_t* const usrc = block_to_save + U_OFF;
    if (x < enc->mb_w_ - 1) {   // left
      int i;
      for (i = 0; i < 16; ++i) {
        enc->y_left_[i] = ysrc[15 + i * BPS];
      }
      for (i = 0; i < 8; ++i) {
        enc->u_left_[i] = usrc[7 + i * BPS];
        enc->v_left_[i] = usrc[15 + i * BPS];
      }
      // top-left (before 'top'!)
      enc->y_left_[-1] = enc->y_top_[x * 16 + 15];
      enc->u_left_[-1] = enc->uv_top_[x * 16 + 0 + 7];
      enc->v_left_[-1] = enc->uv_top_[x * 16 + 8 + 7];
    }
    if (y < enc->mb_h_ - 1) {  // top
      memcpy(enc->y_top_ + x * 16, ysrc + 15 * BPS, 16);
      memcpy(enc->uv_top_ + x * 16, usrc + 7 * BPS, 8 + 8);
    }
  }

  it->mb_++;
  it->preds_ += 4;
  it->nz_++;
  it->x_++;
  if (it->x_ == enc->mb_w_) {
    it->x_ = 0;
    it->y_++;
    it->bw_ = &enc->parts_[it->y_ & (enc->num_parts_ - 1)];
    it->preds_ = enc->preds_ + it->y_ * 4 * enc->preds_w_;
    it->nz_ = enc->nz_;
    InitLeft(it);
  }
  return (0 < --it->done_);
}

//------------------------------------------------------------------------------
// Helper function to set mode properties

void VP8SetIntra16Mode(const VP8EncIterator* const it, int mode) {
  uint8_t* preds = it->preds_;
  int y;
  for (y = 0; y < 4; ++y) {
    memset(preds, mode, 4);
    preds += it->enc_->preds_w_;
  }
  it->mb_->type_ = 1;
}

void VP8SetIntra4Mode(const VP8EncIterator* const it, const uint8_t* modes) {
  uint8_t* preds = it->preds_;
  int y;
  for (y = 4; y > 0; --y) {
    memcpy(preds, modes, 4 * sizeof(*modes));
    preds += it->enc_->preds_w_;
    modes += 4;
  }
  it->mb_->type_ = 0;
}

void VP8SetIntraUVMode(const VP8EncIterator* const it, int mode) {
  it->mb_->uv_mode_ = mode;
}

void VP8SetSkip(const VP8EncIterator* const it, int skip) {
  it->mb_->skip_ = skip;
}

void VP8SetSegment(const VP8EncIterator* const it, int segment) {
  it->mb_->segment_ = segment;
}

//------------------------------------------------------------------------------
// Intra4x4 sub-blocks iteration
//
//  We store and update the boundary samples into an array of 37 pixels. They
//  are updated as we iterate and reconstructs each intra4x4 blocks in turn.
//  The position of the samples has the following snake pattern:
//
// 16|17 18 19 20|21 22 23 24|25 26 27 28|29 30 31 32|33 34 35 36  <- Top-right
// --+-----------+-----------+-----------+-----------+
// 15|         19|         23|         27|         31|
// 14|         18|         22|         26|         30|
// 13|         17|         21|         25|         29|
// 12|13 14 15 16|17 18 19 20|21 22 23 24|25 26 27 28|
// --+-----------+-----------+-----------+-----------+
// 11|         15|         19|         23|         27|
// 10|         14|         18|         22|         26|
//  9|         13|         17|         21|         25|
//  8| 9 10 11 12|13 14 15 16|17 18 19 20|21 22 23 24|
// --+-----------+-----------+-----------+-----------+
//  7|         11|         15|         19|         23|
//  6|         10|         14|         18|         22|
//  5|          9|         13|         17|         21|
//  4| 5  6  7  8| 9 10 11 12|13 14 15 16|17 18 19 20|
// --+-----------+-----------+-----------+-----------+
//  3|          7|         11|         15|         19|
//  2|          6|         10|         14|         18|
//  1|          5|          9|         13|         17|
//  0| 1  2  3  4| 5  6  7  8| 9 10 11 12|13 14 15 16|
// --+-----------+-----------+-----------+-----------+

// Array to record the position of the top sample to pass to the prediction
// functions in dsp.c.
static const uint8_t VP8TopLeftI4[16] = {
  17, 21, 25, 29,
  13, 17, 21, 25,
  9,  13, 17, 21,
  5,   9, 13, 17
};

void VP8IteratorStartI4(VP8EncIterator* const it) {
  const VP8Encoder* const enc = it->enc_;
  int i;

  it->i4_ = 0;    // first 4x4 sub-block
  it->i4_top_ = it->i4_boundary_ + VP8TopLeftI4[0];

  // Import the boundary samples
  for (i = 0; i < 17; ++i) {    // left
    it->i4_boundary_[i] = enc->y_left_[15 - i];
  }
  for (i = 0; i < 16; ++i) {    // top
    it->i4_boundary_[17 + i] = enc->y_top_[it->x_ * 16 + i];
  }
  // top-right samples have a special case on the far right of the picture
  if (it->x_ < enc->mb_w_ - 1) {
    for (i = 16; i < 16 + 4; ++i) {
      it->i4_boundary_[17 + i] = enc->y_top_[it->x_ * 16 + i];
    }
  } else {    // else, replicate the last valid pixel four times
    for (i = 16; i < 16 + 4; ++i) {
      it->i4_boundary_[17 + i] = it->i4_boundary_[17 + 15];
    }
  }
  VP8IteratorNzToBytes(it);  // import the non-zero context
}

int VP8IteratorRotateI4(VP8EncIterator* const it,
                        const uint8_t* const yuv_out) {
  const uint8_t* const blk = yuv_out + VP8Scan[it->i4_];
  uint8_t* const top = it->i4_top_;
  int i;

  // Update the cache with 7 fresh samples
  for (i = 0; i <= 3; ++i) {
    top[-4 + i] = blk[i + 3 * BPS];   // store future top samples
  }
  if ((it->i4_ & 3) != 3) {  // if not on the right sub-blocks #3, #7, #11, #15
    for (i = 0; i <= 2; ++i) {        // store future left samples
      top[i] = blk[3 + (2 - i) * BPS];
    }
  } else {  // else replicate top-right samples, as says the specs.
    for (i = 0; i <= 3; ++i) {
      top[i] = top[i + 4];
    }
  }
  // move pointers to next sub-block
  ++it->i4_;
  if (it->i4_ == 16) {    // we're done
    return 0;
  }

  it->i4_top_ = it->i4_boundary_ + VP8TopLeftI4[it->i4_];
  return 1;
}

//------------------------------------------------------------------------------

#if defined(__cplusplus) || defined(c_plusplus)
}    // extern "C"
#endif