text: // Copyright 2010 Google Inc.
  //
  // This code is licensed under the same terms as WebM:
  //  Software License Agreement:  http://www.webmproject.org/license/software/
  //  Additional IP Rights Grant:  http://www.webmproject.org/license/additional/
  // -----------------------------------------------------------------------------
  //
  // Frame-reconstruction function. Memory allocation.
  //
  // Author: Skal (pascal.massimino@gmail.com)
  
  #include <stdlib.h>
  #include "vp8i.h"
  
  #if defined(__cplusplus) || defined(c_plusplus)
  extern "C" {
  #endif
  
  #define ALIGN_MASK (32 - 1)
  
  //-----------------------------------------------------------------------------
  // Memory setup
  
  // how many extra luma lines are needed for caching, given a filtering level
  static const uint8_t kFilterExtraRows[3] = { 0, 4, 8 };
  
  int VP8InitFrame(VP8Decoder* const dec, VP8Io* io) {
    const int mb_w = dec->mb_w_;
    const int intra_pred_mode_size = 4 * mb_w * sizeof(uint8_t);
    const int top_size = (16 + 8 + 8) * mb_w;
    const int info_size = (mb_w + 1) * sizeof(VP8MB);
    const int yuv_size = YUV_SIZE * sizeof(*dec->yuv_b_);
    const int coeffs_size = 384 * sizeof(*dec->coeffs_);
    const int cache_height = (16 + kFilterExtraRows[dec->filter_type_]) * 3 / 2;
    const int cache_size = top_size * cache_height;
    const int needed = intra_pred_mode_size
                     + top_size + info_size
                     + yuv_size + coeffs_size
                     + cache_size + ALIGN_MASK;
    uint8_t* mem;
  
    if (needed > dec->mem_size_) {
      free(dec->mem_);
      dec->mem_size_ = 0;
      dec->mem_ = (uint8_t*)malloc(needed);
      if (dec->mem_ == NULL) {
        return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY,
                           "no memory during frame initialization.");
      }
      dec->mem_size_ = needed;
    }
  
    mem = (uint8_t*)dec->mem_;
    dec->intra_t_ = (uint8_t*)mem;
    mem += intra_pred_mode_size;
  
    dec->y_t_ = (uint8_t*)mem;
    mem += 16 * mb_w;
    dec->u_t_ = (uint8_t*)mem;
    mem += 8 * mb_w;
    dec->v_t_ = (uint8_t*)mem;
    mem += 8 * mb_w;
  
    dec->mb_info_ = ((VP8MB*)mem) + 1;
    mem += info_size;
  
    mem = (uint8_t*)((uintptr_t)(mem + ALIGN_MASK) & ~ALIGN_MASK);
    assert((yuv_size & ALIGN_MASK) == 0);
    dec->yuv_b_ = (uint8_t*)mem;
    mem += yuv_size;
  
    dec->coeffs_ = (int16_t*)mem;
    mem += coeffs_size;
  
    dec->cache_y_stride_ = 16 * mb_w;
    dec->cache_uv_stride_ = 8 * mb_w;
    {
      const int extra_rows = kFilterExtraRows[dec->filter_type_];
      const int extra_y = extra_rows * dec->cache_y_stride_;
      const int extra_uv = (extra_rows / 2) * dec->cache_uv_stride_;
      dec->cache_y_ = ((uint8_t*)mem) + extra_y;
      dec->cache_u_ = dec->cache_y_ + 16 * dec->cache_y_stride_ + extra_uv;
      dec->cache_v_ = dec->cache_u_ + 8 * dec->cache_uv_stride_ + extra_uv;
    }
    mem += cache_size;
  
    // note: left-info is initialized once for all.
    memset(dec->mb_info_ - 1, 0, (mb_w + 1) * sizeof(*dec->mb_info_));
  
    // initialize top
    memset(dec->intra_t_, B_DC_PRED, intra_pred_mode_size);
  
    // prepare 'io'
    io->width = dec->pic_hdr_.width_;
    io->height = dec->pic_hdr_.height_;
    io->mb_y = 0;
    io->y = dec->cache_y_;
    io->u = dec->cache_u_;
    io->v = dec->cache_v_;
    io->y_stride = dec->cache_y_stride_;
    io->uv_stride = dec->cache_uv_stride_;
    io->fancy_upscaling = 0;    // default
  
    // Init critical function pointers and look-up tables.
    VP8DspInitTables();
    VP8DspInit();
  
    return 1;
  }
  
  //-----------------------------------------------------------------------------
  // Filtering
  
  static inline int hev_thresh_from_level(int level, int keyframe) {
    if (keyframe) {
      return (level >= 40) ? 2 : (level >= 15) ? 1 : 0;
    } else {
      return (level >= 40) ? 3 : (level >= 20) ? 2 : (level >= 15) ? 1 : 0;
    }
  }
  
  static void DoFilter(VP8Decoder* const dec, int mb_x, int mb_y) {
    VP8MB* const mb = dec->mb_info_ + mb_x;
    uint8_t* const y_dst = dec->cache_y_ + mb_x * 16;
    const int y_bps = dec->cache_y_stride_;
    const int level = mb->f_level_;
    const int ilevel = mb->f_ilevel_;
    const int limit = 2 * level + ilevel;
    if (level == 0) {
      return;
    }
    if (dec->filter_type_ == 1) {   // simple
      if (mb_x > 0) {
        VP8SimpleHFilter16(y_dst, y_bps, limit + 4);
      }
      if (mb->f_inner_) {
        VP8SimpleHFilter16i(y_dst, y_bps, limit);
      }
      if (mb_y > 0) {
        VP8SimpleVFilter16(y_dst, y_bps, limit + 4);
      }
      if (mb->f_inner_) {
        VP8SimpleVFilter16i(y_dst, y_bps, limit);
      }
    } else {    // complex
      uint8_t* const u_dst = dec->cache_u_ + mb_x * 8;
      uint8_t* const v_dst = dec->cache_v_ + mb_x * 8;
      const int uv_bps = dec->cache_uv_stride_;
      const int hev_thresh =
          hev_thresh_from_level(level, dec->frm_hdr_.key_frame_);
      if (mb_x > 0) {
        VP8HFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh);
        VP8HFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh);
      }
      if (mb->f_inner_) {
        VP8HFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh);
        VP8HFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh);
      }
      if (mb_y > 0) {
        VP8VFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh);
        VP8VFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh);
      }
      if (mb->f_inner_) {
        VP8VFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh);
        VP8VFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh);
      }
    }
  }
  
  void VP8StoreBlock(VP8Decoder* const dec) {
    if (dec->filter_type_ > 0) {
      VP8MB* const info = dec->mb_info_ + dec->mb_x_;
      int level = dec->filter_levels_[dec->segment_];
      if (dec->filter_hdr_.use_lf_delta_) {
        // TODO(skal): only CURRENT is handled for now.
        level += dec->filter_hdr_.ref_lf_delta_[0];
        if (dec->is_i4x4_) {
          level += dec->filter_hdr_.mode_lf_delta_[0];
        }
      }
      level = (level < 0) ? 0 : (level > 63) ? 63 : level;
      info->f_level_ = level;
  
      if (dec->filter_hdr_.sharpness_ > 0) {
        if (dec->filter_hdr_.sharpness_ > 4) {
          level >>= 2;
        } else {
          level >>= 1;
        }
        if (level > 9 - dec->filter_hdr_.sharpness_) {
          level = 9 - dec->filter_hdr_.sharpness_;
        }
      }
  
      info->f_ilevel_ = (level < 1) ? 1 : level;
      info->f_inner_ = (!info->skip_ || dec->is_i4x4_);
    }
    {
      // Transfer samples to row cache
      int y;
      uint8_t* const ydst = dec->cache_y_ + dec->mb_x_ * 16;
      uint8_t* const udst = dec->cache_u_ + dec->mb_x_ * 8;
      uint8_t* const vdst = dec->cache_v_ + dec->mb_x_ * 8;
      for (y = 0; y < 16; ++y) {
        memcpy(ydst + y * dec->cache_y_stride_,
               dec->yuv_b_ + Y_OFF + y * BPS, 16);
      }
      for (y = 0; y < 8; ++y) {
        memcpy(udst + y * dec->cache_uv_stride_,
             dec->yuv_b_ + U_OFF + y * BPS, 8);
        memcpy(vdst + y * dec->cache_uv_stride_,
             dec->yuv_b_ + V_OFF + y * BPS, 8);
      }
    }
  }
  
  int VP8FinishRow(VP8Decoder* const dec, VP8Io* io) {
    const int extra_y_rows = kFilterExtraRows[dec->filter_type_];
    const int ysize = extra_y_rows * dec->cache_y_stride_;
    const int uvsize = (extra_y_rows / 2) * dec->cache_uv_stride_;
    const int first_row = (dec->mb_y_ == 0);
    const int last_row = (dec->mb_y_ >= dec->mb_h_ - 1);
    uint8_t* const ydst = dec->cache_y_ - ysize;
    uint8_t* const udst = dec->cache_u_ - uvsize;
    uint8_t* const vdst = dec->cache_v_ - uvsize;
    if (dec->filter_type_ > 0) {
      int mb_x;
      for (mb_x = 0; mb_x < dec->mb_w_; ++mb_x) {
        DoFilter(dec, mb_x, dec->mb_y_);
      }
    }
    if (io->put) {
      int y_start = dec->mb_y_ * 16;
      int y_end = y_start + 16;
      if (!first_row) {
        y_start -= extra_y_rows;
        io->y = ydst;
        io->u = udst;
        io->v = vdst;
      } else {
        io->y = dec->cache_y_;
        io->u = dec->cache_u_;
        io->v = dec->cache_v_;
      }
      if (!last_row) {
        y_end -= extra_y_rows;
      }
      if (y_end > io->height) {
        y_end = io->height;
      }
      io->mb_y = y_start;
      io->mb_h = y_end - y_start;
      if (!io->put(io)) {
        return 0;
      }
    }
      // rotate top samples
    if (!last_row) {
      memcpy(ydst, ydst + 16 * dec->cache_y_stride_, ysize);
      memcpy(udst, udst + 8 * dec->cache_uv_stride_, uvsize);
      memcpy(vdst, vdst + 8 * dec->cache_uv_stride_, uvsize);
    }
    return 1;
  }
  
  //-----------------------------------------------------------------------------
  // Main reconstruction function.
  
  static const int kScan[16] = {
    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
  };
  
  static inline int CheckMode(VP8Decoder* const dec, int mode) {
    if (mode == B_DC_PRED) {
      if (dec->mb_x_ == 0) {
        return (dec->mb_y_ == 0) ? B_DC_PRED_NOTOPLEFT : B_DC_PRED_NOLEFT;
      } else {
        return (dec->mb_y_ == 0) ? B_DC_PRED_NOTOP : B_DC_PRED;
      }
    }
    return mode;
  }
  
  static inline void Copy32b(uint8_t* dst, uint8_t* src) {
    *(uint32_t*)dst = *(uint32_t*)src;
  }
  
  void VP8ReconstructBlock(VP8Decoder* const dec) {
    uint8_t* const y_dst = dec->yuv_b_ + Y_OFF;
    uint8_t* const u_dst = dec->yuv_b_ + U_OFF;
    uint8_t* const v_dst = dec->yuv_b_ + V_OFF;
  
    // Rotate in the left samples from previously decoded block. We move four
    // pixels at a time for alignment reason, and because of in-loop filter.
    if (dec->mb_x_ > 0) {
      int j;
      for (j = -1; j < 16; ++j) {
        Copy32b(&y_dst[j * BPS - 4], &y_dst[j * BPS + 12]);
      }
      for (j = -1; j < 8; ++j) {
        Copy32b(&u_dst[j * BPS - 4], &u_dst[j * BPS + 4]);
        Copy32b(&v_dst[j * BPS - 4], &v_dst[j * BPS + 4]);
      }
    } else {
      int j;
      for (j = 0; j < 16; ++j) {
        y_dst[j * BPS - 1] = 129;
      }
      for (j = 0; j < 8; ++j) {
        u_dst[j * BPS - 1] = 129;
        v_dst[j * BPS - 1] = 129;
      }
      // Init top-left sample on left column too
      if (dec->mb_y_ > 0) {
        y_dst[-1 - BPS] = u_dst[-1 - BPS] = v_dst[-1 - BPS] = 129;
      }
    }
    {
      // bring top samples into the cache
      uint8_t* const top_y = dec->y_t_ + dec->mb_x_ * 16;
      uint8_t* const top_u = dec->u_t_ + dec->mb_x_ * 8;
      uint8_t* const top_v = dec->v_t_ + dec->mb_x_ * 8;
      const int16_t* coeffs = dec->coeffs_;
      int n;
  
      if (dec->mb_y_ > 0) {
        memcpy(y_dst - BPS, top_y, 16);
        memcpy(u_dst - BPS, top_u, 8);
        memcpy(v_dst - BPS, top_v, 8);
      } else if (dec->mb_x_ == 0) {
        // we only need to do this init once at block (0,0).
        // Afterward, it remains valid for the whole topmost row.
        memset(y_dst - BPS - 1, 127, 16 + 4 + 1);
        memset(u_dst - BPS - 1, 127, 8 + 1);
        memset(v_dst - BPS - 1, 127, 8 + 1);
      }
  
      // predict and add residuals
  
      if (dec->is_i4x4_) {   // 4x4
        uint32_t* const top_right = (uint32_t*)(y_dst - BPS + 16);
  
        if (dec->mb_y_ > 0) {
          if (dec->mb_x_ >= dec->mb_w_ - 1) {    // on rightmost border
            top_right[0] = top_y[15] * 0x01010101u;
          } else {
            memcpy(top_right, top_y + 16, sizeof(*top_right));
          }
        }
        // replicate the top-right pixels below
        top_right[BPS] = top_right[2 * BPS] = top_right[3 * BPS] = top_right[0];
  
        // predict and add residues for all 4x4 blocks in turn.
        for (n = 0; n < 16; n++) {
          uint8_t* const dst = y_dst + kScan[n];
          VP8PredLuma4[dec->imodes_[n]](dst);
          if (dec->non_zero_ac_ & (1 << n)) {
            VP8Transform(coeffs + n * 16, dst);
          } else if (dec->non_zero_ & (1 << n)) {  // only DC is present
            VP8TransformDC(coeffs + n * 16, dst);
          }
        }
      } else {    // 16x16
        const int pred_func = CheckMode(dec, dec->imodes_[0]);
        VP8PredLuma16[pred_func](y_dst);
        if (dec->non_zero_) {
          for (n = 0; n < 16; n++) {
            uint8_t* const dst = y_dst + kScan[n];
            if (dec->non_zero_ac_ & (1 << n)) {
              VP8Transform(coeffs + n * 16, dst);
            } else if (dec->non_zero_ & (1 << n)) {  // only DC is present
              VP8TransformDC(coeffs + n * 16, dst);
            }
          }
        }
      }
      {
        // Chroma
        const int pred_func = CheckMode(dec, dec->uvmode_);
        VP8PredChroma8[pred_func](u_dst);
        VP8PredChroma8[pred_func](v_dst);
  
        if (dec->non_zero_ & 0x0f0000) {   // chroma-U
          const int16_t* const u_coeffs = dec->coeffs_ + 16 * 16;
          if (dec->non_zero_ac_ & 0x0f0000) {
            VP8TransformUV(u_coeffs, u_dst);
          } else {
            VP8TransformDCUV(u_coeffs, u_dst);
          }
        }
        if (dec->non_zero_ & 0xf00000) {   // chroma-V
          const int16_t* const v_coeffs = dec->coeffs_ + 20 * 16;
          if (dec->non_zero_ac_ & 0xf00000) {
            VP8TransformUV(v_coeffs, v_dst);
          } else {
            VP8TransformDCUV(v_coeffs, v_dst);
          }
        }
  
        // stash away top samples for next block
        if (dec->mb_y_ < dec->mb_h_ - 1) {
          memcpy(top_y, y_dst + 15 * BPS, 16);
          memcpy(top_u, u_dst +  7 * BPS,  8);
          memcpy(top_v, v_dst +  7 * BPS,  8);
        }
      }
    }
  }
  
  //-----------------------------------------------------------------------------
  
  #if defined(__cplusplus) || defined(c_plusplus)
  }    // extern "C"
  #endif
  