vp9_decodframe.c

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE 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.
 */


#include "vp9/decoder/vp9_onyxd_int.h"
#include "vp9/common/vp9_common.h"
#include "vp9/common/vp9_header.h"
#include "vp9/common/vp9_reconintra.h"
#include "vp9/common/vp9_reconinter.h"
#include "vp9/common/vp9_entropy.h"
#include "vp9/decoder/vp9_decodframe.h"
#include "vp9/decoder/vp9_detokenize.h"
#include "vp9/common/vp9_invtrans.h"
#include "vp9/common/vp9_alloccommon.h"
#include "vp9/common/vp9_entropymode.h"
#include "vp9/common/vp9_quant_common.h"
#include "vpx_scale/vpx_scale.h"
#include "vp9/common/vp9_setupintrarecon.h"

#include "vp9/decoder/vp9_decodemv.h"
#include "vp9/common/vp9_extend.h"
#include "vp9/common/vp9_modecont.h"
#include "vpx_mem/vpx_mem.h"
#include "vp9/decoder/vp9_dboolhuff.h"

#include "vp9/common/vp9_seg_common.h"
#include "vp9/common/vp9_tile_common.h"
#include "vp9_rtcd.h"

#include <assert.h>
#include <stdio.h>

#define COEFCOUNT_TESTING

// #define DEC_DEBUG
#ifdef DEC_DEBUG
int dec_debug = 0;
#endif


static int read_le16(const uint8_t *p) {
  return (p[1] << 8) | p[0];
}

static int read_le32(const uint8_t *p) {
  return (p[3] << 24) | (p[2] << 16) | (p[1] << 8) | p[0];
}

// len == 0 is not allowed
static int read_is_valid(const unsigned char *start, size_t len,
                         const unsigned char *end) {
  return start + len > start && start + len <= end;
}

static int merge_index(int v, int n, int modulus) {
  int max1 = (n - 1 - modulus / 2) / modulus + 1;
  if (v < max1) v = v * modulus + modulus / 2;
  else {
    int w;
    v -= max1;
    w = v;
    v += (v + modulus - modulus / 2) / modulus;
    while (v % modulus == modulus / 2 ||
           w != v - (v + modulus - modulus / 2) / modulus) v++;
  }
  return v;
}

static int inv_remap_prob(int v, int m) {
  const int n = 256;
  const int modulus = MODULUS_PARAM;

  v = merge_index(v, n - 1, modulus);
  if ((m << 1) <= n) {
    return vp9_inv_recenter_nonneg(v + 1, m);
  } else {
    return n - 1 - vp9_inv_recenter_nonneg(v + 1, n - 1 - m);
  }
}

static vp9_prob read_prob_diff_update(vp9_reader *const bc, int oldp) {
  int delp = vp9_decode_term_subexp(bc, SUBEXP_PARAM, 255);
  return (vp9_prob)inv_remap_prob(delp, oldp);
}

void vp9_init_de_quantizer(VP9D_COMP *pbi) {
  int i;
  int q;
  VP9_COMMON *const pc = &pbi->common;

  for (q = 0; q < QINDEX_RANGE; q++) {
    pc->Y1dequant[q][0] = (int16_t)vp9_dc_quant(q, pc->y1dc_delta_q);
    pc->UVdequant[q][0] = (int16_t)vp9_dc_uv_quant(q, pc->uvdc_delta_q);

    /* all the ac values =; */
    for (i = 1; i < 16; i++) {
      int rc = vp9_default_zig_zag1d_4x4[i];

      pc->Y1dequant[q][rc] = (int16_t)vp9_ac_yquant(q);
      pc->UVdequant[q][rc] = (int16_t)vp9_ac_uv_quant(q, pc->uvac_delta_q);
    }
  }
}

static int get_qindex(MACROBLOCKD *mb, int segment_id, int base_qindex) {
  // Set the Q baseline allowing for any segment level adjustment
  if (vp9_segfeature_active(mb, segment_id, SEG_LVL_ALT_Q)) {
    if (mb->mb_segment_abs_delta == SEGMENT_ABSDATA)
      return vp9_get_segdata(mb, segment_id, SEG_LVL_ALT_Q);  // Abs Value
    else
      return clamp(base_qindex + vp9_get_segdata(mb, segment_id, SEG_LVL_ALT_Q),
                   0, MAXQ);  // Delta Value
  } else {
    return base_qindex;
  }
}

static void mb_init_dequantizer(VP9D_COMP *pbi, MACROBLOCKD *mb) {
  int i;

  VP9_COMMON *const pc = &pbi->common;
  const int segment_id = mb->mode_info_context->mbmi.segment_id;
  const int qindex = get_qindex(mb, segment_id, pc->base_qindex);
  mb->q_index = qindex;

  for (i = 0; i < 16; i++)
    mb->block[i].dequant = pc->Y1dequant[qindex];

  for (i = 16; i < 24; i++)
    mb->block[i].dequant = pc->UVdequant[qindex];

  if (mb->lossless) {
    assert(qindex == 0);
    mb->inv_txm4x4_1      = vp9_short_iwalsh4x4_1;
    mb->inv_txm4x4        = vp9_short_iwalsh4x4;
    mb->itxm_add          = vp9_dequant_idct_add_lossless_c;
    mb->itxm_add_y_block  = vp9_dequant_idct_add_y_block_lossless_c;
    mb->itxm_add_uv_block = vp9_dequant_idct_add_uv_block_lossless_c;
  } else {
    mb->inv_txm4x4_1      = vp9_short_idct4x4_1;
    mb->inv_txm4x4        = vp9_short_idct4x4;
    mb->itxm_add          = vp9_dequant_idct_add;
    mb->itxm_add_y_block  = vp9_dequant_idct_add_y_block;
    mb->itxm_add_uv_block = vp9_dequant_idct_add_uv_block;
  }
}

/* skip_recon_mb() is Modified: Instead of writing the result to predictor buffer and then copying it
 *  to dst buffer, we can write the result directly to dst buffer. This eliminates unnecessary copy.
 */
static void skip_recon_mb(VP9D_COMP *pbi, MACROBLOCKD *xd,
                          int mb_row, int mb_col) {
  BLOCK_SIZE_TYPE sb_type = xd->mode_info_context->mbmi.sb_type;

  if (xd->mode_info_context->mbmi.ref_frame == INTRA_FRAME) {
    if (sb_type == BLOCK_SIZE_SB64X64) {
      vp9_build_intra_predictors_sb64uv_s(xd);
      vp9_build_intra_predictors_sb64y_s(xd);
    } else if (sb_type == BLOCK_SIZE_SB32X32) {
      vp9_build_intra_predictors_sbuv_s(xd);
      vp9_build_intra_predictors_sby_s(xd);
    } else {
      vp9_build_intra_predictors_mbuv_s(xd);
      vp9_build_intra_predictors_mby_s(xd);
    }
  } else {
    if (sb_type == BLOCK_SIZE_SB64X64) {
      vp9_build_inter64x64_predictors_sb(xd,
                                         xd->dst.y_buffer,
                                         xd->dst.u_buffer,
                                         xd->dst.v_buffer,
                                         xd->dst.y_stride,
                                         xd->dst.uv_stride,
                                         mb_row, mb_col);
    } else if (sb_type == BLOCK_SIZE_SB32X32) {
      vp9_build_inter32x32_predictors_sb(xd,
                                         xd->dst.y_buffer,
                                         xd->dst.u_buffer,
                                         xd->dst.v_buffer,
                                         xd->dst.y_stride,
                                         xd->dst.uv_stride,
                                         mb_row, mb_col);
    } else {
      vp9_build_inter16x16_predictors_mb(xd,
                                         xd->dst.y_buffer,
                                         xd->dst.u_buffer,
                                         xd->dst.v_buffer,
                                         xd->dst.y_stride,
                                         xd->dst.uv_stride,
                                         mb_row, mb_col);
#if CONFIG_COMP_INTERINTRA_PRED
      if (xd->mode_info_context->mbmi.second_ref_frame == INTRA_FRAME) {
        vp9_build_interintra_16x16_predictors_mb(xd,
                                                 xd->dst.y_buffer,
                                                 xd->dst.u_buffer,
                                                 xd->dst.v_buffer,
                                                 xd->dst.y_stride,
                                                 xd->dst.uv_stride);
      }
#endif
    }
  }
}

static void decode_16x16(VP9D_COMP *pbi, MACROBLOCKD *xd,
                         BOOL_DECODER* const bc) {
  TX_TYPE tx_type = get_tx_type_16x16(xd, 0);
#ifdef DEC_DEBUG
  if (dec_debug) {
    int i;
    printf("\n");
    printf("qcoeff 16x16\n");
    for (i = 0; i < 400; i++) {
      printf("%3d ", xd->qcoeff[i]);
      if (i % 16 == 15) printf("\n");
    }
    printf("\n");
    printf("predictor\n");
    for (i = 0; i < 400; i++) {
      printf("%3d ", xd->predictor[i]);
      if (i % 16 == 15) printf("\n");
    }
  }
#endif
  if (tx_type != DCT_DCT) {
    vp9_ht_dequant_idct_add_16x16_c(tx_type, xd->qcoeff,
                                    xd->block[0].dequant, xd->predictor,
                                    xd->dst.y_buffer, 16, xd->dst.y_stride,
                                    xd->eobs[0]);
  } else {
    vp9_dequant_idct_add_16x16(xd->qcoeff, xd->block[0].dequant,
                               xd->predictor, xd->dst.y_buffer,
                               16, xd->dst.y_stride, xd->eobs[0]);
  }
  vp9_dequant_idct_add_uv_block_8x8(
      xd->qcoeff + 16 * 16, xd->block[16].dequant,
      xd->predictor + 16 * 16, xd->dst.u_buffer, xd->dst.v_buffer,
      xd->dst.uv_stride, xd);
}

static void decode_8x8(VP9D_COMP *pbi, MACROBLOCKD *xd,
                       BOOL_DECODER* const bc) {
  // First do Y
  // if the first one is DCT_DCT assume all the rest are as well
  TX_TYPE tx_type = get_tx_type_8x8(xd, 0);
#ifdef DEC_DEBUG
  if (dec_debug) {
    int i;
    printf("\n");
    printf("qcoeff 8x8\n");
    for (i = 0; i < 384; i++) {
      printf("%3d ", xd->qcoeff[i]);
      if (i % 16 == 15) printf("\n");
    }
  }
#endif
  if (tx_type != DCT_DCT || xd->mode_info_context->mbmi.mode == I8X8_PRED) {
    int i;
    for (i = 0; i < 4; i++) {
      int ib = vp9_i8x8_block[i];
      int idx = (ib & 0x02) ? (ib + 2) : ib;
      int16_t *q  = xd->block[idx].qcoeff;
      int16_t *dq = xd->block[0].dequant;
      uint8_t *pre = xd->block[ib].predictor;
      uint8_t *dst = *(xd->block[ib].base_dst) + xd->block[ib].dst;
      int stride = xd->dst.y_stride;
      BLOCKD *b = &xd->block[ib];
      if (xd->mode_info_context->mbmi.mode == I8X8_PRED) {
        int i8x8mode = b->bmi.as_mode.first;
        vp9_intra8x8_predict(xd, b, i8x8mode, b->predictor);
      }
      tx_type = get_tx_type_8x8(xd, ib);
      if (tx_type != DCT_DCT) {
        vp9_ht_dequant_idct_add_8x8_c(tx_type, q, dq, pre, dst, 16, stride,
                                      xd->eobs[idx]);
      } else {
        vp9_dequant_idct_add_8x8_c(q, dq, pre, dst, 16, stride,
                                   xd->eobs[idx]);
      }
    }
  } else {
    vp9_dequant_idct_add_y_block_8x8(xd->qcoeff,
                                     xd->block[0].dequant,
                                     xd->predictor,
                                     xd->dst.y_buffer,
                                     xd->dst.y_stride,
                                     xd);
  }

  // Now do UV
  if (xd->mode_info_context->mbmi.mode == I8X8_PRED) {
    int i;
    for (i = 0; i < 4; i++) {
      int ib = vp9_i8x8_block[i];
      BLOCKD *b = &xd->block[ib];
      int i8x8mode = b->bmi.as_mode.first;

      b = &xd->block[16 + i];
      vp9_intra_uv4x4_predict(xd, b, i8x8mode, b->predictor);
      xd->itxm_add(b->qcoeff, b->dequant, b->predictor,
                   *(b->base_dst) + b->dst, 8, b->dst_stride, xd->eobs[16 + i]);

      b = &xd->block[20 + i];
      vp9_intra_uv4x4_predict(xd, b, i8x8mode, b->predictor);
      xd->itxm_add(b->qcoeff, b->dequant, b->predictor,
                   *(b->base_dst) + b->dst, 8, b->dst_stride, xd->eobs[20 + i]);
    }
  } else if (xd->mode_info_context->mbmi.mode == SPLITMV) {
    xd->itxm_add_uv_block(xd->qcoeff + 16 * 16, xd->block[16].dequant,
         xd->predictor + 16 * 16, xd->dst.u_buffer, xd->dst.v_buffer,
         xd->dst.uv_stride, xd);
  } else {
    vp9_dequant_idct_add_uv_block_8x8
        (xd->qcoeff + 16 * 16, xd->block[16].dequant,
         xd->predictor + 16 * 16, xd->dst.u_buffer, xd->dst.v_buffer,
         xd->dst.uv_stride, xd);
  }
#ifdef DEC_DEBUG
  if (dec_debug) {
    int i;
    printf("\n");
    printf("predictor\n");
    for (i = 0; i < 384; i++) {
      printf("%3d ", xd->predictor[i]);
      if (i % 16 == 15) printf("\n");
    }
  }
#endif
}

static void decode_4x4(VP9D_COMP *pbi, MACROBLOCKD *xd,
                       BOOL_DECODER* const bc) {
  TX_TYPE tx_type;
  int i, eobtotal = 0;
  MB_PREDICTION_MODE mode = xd->mode_info_context->mbmi.mode;
  if (mode == I8X8_PRED) {
    for (i = 0; i < 4; i++) {
      int ib = vp9_i8x8_block[i];
      const int iblock[4] = {0, 1, 4, 5};
      int j;
      BLOCKD *b = &xd->block[ib];
      int i8x8mode = b->bmi.as_mode.first;
      vp9_intra8x8_predict(xd, b, i8x8mode, b->predictor);
      for (j = 0; j < 4; j++) {
        b = &xd->block[ib + iblock[j]];
        tx_type = get_tx_type_4x4(xd, ib + iblock[j]);
        if (tx_type != DCT_DCT) {
          vp9_ht_dequant_idct_add_c(tx_type, b->qcoeff,
                                    b->dequant, b->predictor,
                                    *(b->base_dst) + b->dst, 16,
                                    b->dst_stride, xd->eobs[ib + iblock[j]]);
        } else {
          xd->itxm_add(b->qcoeff, b->dequant, b->predictor,
                       *(b->base_dst) + b->dst, 16, b->dst_stride,
                       xd->eobs[ib + iblock[j]]);
        }
      }
      b = &xd->block[16 + i];
      vp9_intra_uv4x4_predict(xd, b, i8x8mode, b->predictor);
      xd->itxm_add(b->qcoeff, b->dequant, b->predictor,
                   *(b->base_dst) + b->dst, 8, b->dst_stride, xd->eobs[16 + i]);
      b = &xd->block[20 + i];
      vp9_intra_uv4x4_predict(xd, b, i8x8mode, b->predictor);
      xd->itxm_add(b->qcoeff, b->dequant, b->predictor,
                   *(b->base_dst) + b->dst, 8, b->dst_stride, xd->eobs[20 + i]);
    }
  } else if (mode == B_PRED) {
    for (i = 0; i < 16; i++) {
      BLOCKD *b = &xd->block[i];
      int b_mode = xd->mode_info_context->bmi[i].as_mode.first;
#if CONFIG_NEWBINTRAMODES
      xd->mode_info_context->bmi[i].as_mode.context = b->bmi.as_mode.context =
          vp9_find_bpred_context(xd, b);
#endif
      if (!xd->mode_info_context->mbmi.mb_skip_coeff)
        eobtotal += vp9_decode_coefs_4x4(pbi, xd, bc, PLANE_TYPE_Y_WITH_DC, i);

      vp9_intra4x4_predict(xd, b, b_mode, b->predictor);
      tx_type = get_tx_type_4x4(xd, i);
      if (tx_type != DCT_DCT) {
        vp9_ht_dequant_idct_add_c(tx_type, b->qcoeff,
                                  b->dequant, b->predictor,
                                  *(b->base_dst) + b->dst, 16, b->dst_stride,
                                  xd->eobs[i]);
      } else {
        xd->itxm_add(b->qcoeff, b->dequant, b->predictor,
                      *(b->base_dst) + b->dst, 16, b->dst_stride, xd->eobs[i]);
      }
    }
    if (!xd->mode_info_context->mbmi.mb_skip_coeff) {
      vp9_decode_mb_tokens_4x4_uv(pbi, xd, bc);
    }
    vp9_build_intra_predictors_mbuv(xd);
    xd->itxm_add_uv_block(xd->qcoeff + 16 * 16,
                           xd->block[16].dequant,
                           xd->predictor + 16 * 16,
                           xd->dst.u_buffer,
                           xd->dst.v_buffer,
                           xd->dst.uv_stride,
                           xd);
  } else if (mode == SPLITMV || get_tx_type_4x4(xd, 0) == DCT_DCT) {
    xd->itxm_add_y_block(xd->qcoeff,
                          xd->block[0].dequant,
                          xd->predictor,
                          xd->dst.y_buffer,
                          xd->dst.y_stride,
                          xd);
    xd->itxm_add_uv_block(xd->qcoeff + 16 * 16,
                           xd->block[16].dequant,
                           xd->predictor + 16 * 16,
                           xd->dst.u_buffer,
                           xd->dst.v_buffer,
                           xd->dst.uv_stride,
                           xd);
  } else {
#ifdef DEC_DEBUG
    if (dec_debug) {
      int i;
      printf("\n");
      printf("qcoeff 4x4\n");
      for (i = 0; i < 400; i++) {
        printf("%3d ", xd->qcoeff[i]);
        if (i % 16 == 15) printf("\n");
      }
      printf("\n");
      printf("predictor\n");
      for (i = 0; i < 400; i++) {
        printf("%3d ", xd->predictor[i]);
        if (i % 16 == 15) printf("\n");
      }
    }
#endif
    for (i = 0; i < 16; i++) {
      BLOCKD *b = &xd->block[i];
      tx_type = get_tx_type_4x4(xd, i);
      if (tx_type != DCT_DCT) {
        vp9_ht_dequant_idct_add_c(tx_type, b->qcoeff,
                                  b->dequant, b->predictor,
                                  *(b->base_dst) + b->dst, 16,
                                  b->dst_stride, xd->eobs[i]);
      } else {
        xd->itxm_add(b->qcoeff, b->dequant, b->predictor,
                      *(b->base_dst) + b->dst, 16, b->dst_stride, xd->eobs[i]);
      }
    }
    xd->itxm_add_uv_block(xd->qcoeff + 16 * 16,
                           xd->block[16].dequant,
                           xd->predictor + 16 * 16,
                           xd->dst.u_buffer,
                           xd->dst.v_buffer,
                           xd->dst.uv_stride,
                           xd);
  }
}

static void decode_superblock64(VP9D_COMP *pbi, MACROBLOCKD *xd,
                                int mb_row, int mb_col,
                                BOOL_DECODER* const bc) {
  int n, eobtotal;
  VP9_COMMON *const pc = &pbi->common;
  MODE_INFO *mi = xd->mode_info_context;
  const int mis = pc->mode_info_stride;

  assert(xd->mode_info_context->mbmi.sb_type == BLOCK_SIZE_SB64X64);

  if (pbi->common.frame_type != KEY_FRAME)
    vp9_setup_interp_filters(xd, xd->mode_info_context->mbmi.interp_filter, pc);

  // re-initialize macroblock dequantizer before detokenization
  if (xd->segmentation_enabled)
    mb_init_dequantizer(pbi, xd);

  if (xd->mode_info_context->mbmi.mb_skip_coeff) {
    vp9_reset_sb64_tokens_context(xd);

    /* Special case:  Force the loopfilter to skip when eobtotal and
     * mb_skip_coeff are zero.
     */
    skip_recon_mb(pbi, xd, mb_row, mb_col);
    return;
  }

  /* do prediction */
  if (xd->mode_info_context->mbmi.ref_frame == INTRA_FRAME) {
    vp9_build_intra_predictors_sb64y_s(xd);
    vp9_build_intra_predictors_sb64uv_s(xd);
  } else {
    vp9_build_inter64x64_predictors_sb(xd, xd->dst.y_buffer,
                                       xd->dst.u_buffer, xd->dst.v_buffer,
                                       xd->dst.y_stride, xd->dst.uv_stride,
                                       mb_row, mb_col);
  }

  /* dequantization and idct */
  eobtotal = vp9_decode_sb64_tokens(pbi, xd, bc);
  if (eobtotal == 0) {  // skip loopfilter
    for (n = 0; n < 16; n++) {
      const int x_idx = n & 3, y_idx = n >> 2;

      if (mb_col + x_idx < pc->mb_cols && mb_row + y_idx < pc->mb_rows)
        mi[y_idx * mis + x_idx].mbmi.mb_skip_coeff = mi->mbmi.mb_skip_coeff;
    }
  } else {
    switch (xd->mode_info_context->mbmi.txfm_size) {
      case TX_32X32:
        for (n = 0; n < 4; n++) {
          const int x_idx = n & 1, y_idx = n >> 1;
          const int y_offset = x_idx * 32 + y_idx * xd->dst.y_stride * 32;
          vp9_dequant_idct_add_32x32(xd->qcoeff + n * 1024,
              xd->block[0].dequant,
              xd->dst.y_buffer + y_offset,
              xd->dst.y_buffer + y_offset,
              xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 64]);
        }
        vp9_dequant_idct_add_32x32(xd->qcoeff + 4096,
            xd->block[16].dequant, xd->dst.u_buffer, xd->dst.u_buffer,
            xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[256]);
        vp9_dequant_idct_add_32x32(xd->qcoeff + 4096 + 1024,
            xd->block[20].dequant, xd->dst.v_buffer, xd->dst.v_buffer,
            xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[320]);
        break;
      case TX_16X16:
        for (n = 0; n < 16; n++) {
          const int x_idx = n & 3, y_idx = n >> 2;
          const int y_offset = y_idx * 16 * xd->dst.y_stride + x_idx * 16;
          const TX_TYPE tx_type = get_tx_type_16x16(xd,
                                                    (y_idx * 16 + x_idx) * 4);

          if (tx_type == DCT_DCT) {
            vp9_dequant_idct_add_16x16(xd->qcoeff + n * 256,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 16]);
          } else {
            vp9_ht_dequant_idct_add_16x16_c(tx_type, xd->qcoeff + n * 256,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 16]);
          }
        }
        for (n = 0; n < 4; n++) {
          const int x_idx = n & 1, y_idx = n >> 1;
          const int uv_offset = y_idx * 16 * xd->dst.uv_stride + x_idx * 16;
          vp9_dequant_idct_add_16x16(xd->qcoeff + 4096 + n * 256,
              xd->block[16].dequant,
              xd->dst.u_buffer + uv_offset,
              xd->dst.u_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[256 + n * 16]);
          vp9_dequant_idct_add_16x16(xd->qcoeff + 4096 + 1024 + n * 256,
              xd->block[20].dequant,
              xd->dst.v_buffer + uv_offset,
              xd->dst.v_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[320 + n * 16]);
        }
        break;
      case TX_8X8:
        for (n = 0; n < 64; n++) {
          const int x_idx = n & 7, y_idx = n >> 3;
          const int y_offset = y_idx * 8 * xd->dst.y_stride + x_idx * 8;
          const TX_TYPE tx_type = get_tx_type_8x8(xd, (y_idx * 16 + x_idx) * 2);
          if (tx_type == DCT_DCT) {
            vp9_dequant_idct_add_8x8_c(xd->qcoeff + n * 64,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 4]);
          } else {
            vp9_ht_dequant_idct_add_8x8_c(tx_type, xd->qcoeff + n * 64,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 4]);
          }
        }
        for (n = 0; n < 16; n++) {
          const int x_idx = n & 3, y_idx = n >> 2;
          const int uv_offset = y_idx * 8 * xd->dst.uv_stride + x_idx * 8;
          vp9_dequant_idct_add_8x8_c(xd->qcoeff + n * 64 + 4096,
              xd->block[16].dequant,
              xd->dst.u_buffer + uv_offset,
              xd->dst.u_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[256 + n * 4]);
          vp9_dequant_idct_add_8x8_c(xd->qcoeff + n * 64 + 4096 + 1024,
              xd->block[20].dequant,
              xd->dst.v_buffer + uv_offset,
              xd->dst.v_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[320 + n * 4]);
        }
        break;
      case TX_4X4:
        for (n = 0; n < 256; n++) {
          const int x_idx = n & 15, y_idx = n >> 4;
          const int y_offset = y_idx * 4 * xd->dst.y_stride + x_idx * 4;
          const TX_TYPE tx_type = get_tx_type_4x4(xd, y_idx * 16 + x_idx);
          if (tx_type == DCT_DCT) {
            xd->itxm_add(xd->qcoeff + n * 16, xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n]);
          } else {
            vp9_ht_dequant_idct_add_c(tx_type, xd->qcoeff + n * 16,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n]);
          }
        }
        for (n = 0; n < 64; n++) {
          const int x_idx = n & 7, y_idx = n >> 3;
          const int uv_offset = y_idx * 4 * xd->dst.uv_stride + x_idx * 4;
          xd->itxm_add(xd->qcoeff + 4096 + n * 16,
              xd->block[16].dequant,
              xd->dst.u_buffer + uv_offset,
              xd->dst.u_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[256 + n]);
          xd->itxm_add(xd->qcoeff + 4096 + 1024 + n * 16,
              xd->block[20].dequant,
              xd->dst.v_buffer + uv_offset,
              xd->dst.v_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[320 + n]);
        }
        break;
      default: assert(0);
    }
  }
}

static void decode_superblock32(VP9D_COMP *pbi, MACROBLOCKD *xd,
                                int mb_row, int mb_col,
                                BOOL_DECODER* const bc) {
  int n, eobtotal;
  VP9_COMMON *const pc = &pbi->common;
  const int mis = pc->mode_info_stride;

  assert(xd->mode_info_context->mbmi.sb_type == BLOCK_SIZE_SB32X32);

  if (pbi->common.frame_type != KEY_FRAME)
    vp9_setup_interp_filters(xd, xd->mode_info_context->mbmi.interp_filter, pc);

  // re-initialize macroblock dequantizer before detokenization
  if (xd->segmentation_enabled)
    mb_init_dequantizer(pbi, xd);

  if (xd->mode_info_context->mbmi.mb_skip_coeff) {
    vp9_reset_sb_tokens_context(xd);

    /* Special case:  Force the loopfilter to skip when eobtotal and
     * mb_skip_coeff are zero.
     */
    skip_recon_mb(pbi, xd, mb_row, mb_col);
    return;
  }

  /* do prediction */
  if (xd->mode_info_context->mbmi.ref_frame == INTRA_FRAME) {
    vp9_build_intra_predictors_sby_s(xd);
    vp9_build_intra_predictors_sbuv_s(xd);
  } else {
    vp9_build_inter32x32_predictors_sb(xd, xd->dst.y_buffer,
                                       xd->dst.u_buffer, xd->dst.v_buffer,
                                       xd->dst.y_stride, xd->dst.uv_stride,
                                       mb_row, mb_col);
  }

  /* dequantization and idct */
  eobtotal = vp9_decode_sb_tokens(pbi, xd, bc);
  if (eobtotal == 0) {  // skip loopfilter
    xd->mode_info_context->mbmi.mb_skip_coeff = 1;
    if (mb_col + 1 < pc->mb_cols)
      xd->mode_info_context[1].mbmi.mb_skip_coeff = 1;
    if (mb_row + 1 < pc->mb_rows) {
      xd->mode_info_context[mis].mbmi.mb_skip_coeff = 1;
      if (mb_col + 1 < pc->mb_cols)
        xd->mode_info_context[mis + 1].mbmi.mb_skip_coeff = 1;
    }
  } else {
    switch (xd->mode_info_context->mbmi.txfm_size) {
      case TX_32X32:
        vp9_dequant_idct_add_32x32(xd->qcoeff, xd->block[0].dequant,
                                   xd->dst.y_buffer, xd->dst.y_buffer,
                                   xd->dst.y_stride, xd->dst.y_stride,
                                   xd->eobs[0]);
        vp9_dequant_idct_add_uv_block_16x16_c(xd->qcoeff + 1024,
                                              xd->block[16].dequant,
                                              xd->dst.u_buffer,
                                              xd->dst.v_buffer,
                                              xd->dst.uv_stride, xd);
        break;
      case TX_16X16:
        for (n = 0; n < 4; n++) {
          const int x_idx = n & 1, y_idx = n >> 1;
          const int y_offset = y_idx * 16 * xd->dst.y_stride + x_idx * 16;
          const TX_TYPE tx_type = get_tx_type_16x16(xd,
                                                    (y_idx * 8 + x_idx) * 4);
          if (tx_type == DCT_DCT) {
            vp9_dequant_idct_add_16x16(
                xd->qcoeff + n * 256, xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 16]);
          } else {
            vp9_ht_dequant_idct_add_16x16_c(tx_type, xd->qcoeff + n * 256,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 16]);
          }
        }
        vp9_dequant_idct_add_uv_block_16x16_c(xd->qcoeff + 1024,
                                              xd->block[16].dequant,
                                              xd->dst.u_buffer,
                                              xd->dst.v_buffer,
                                              xd->dst.uv_stride, xd);
        break;
      case TX_8X8:
        for (n = 0; n < 16; n++) {
          const int x_idx = n & 3, y_idx = n >> 2;
          const int y_offset = y_idx * 8 * xd->dst.y_stride + x_idx * 8;
          const TX_TYPE tx_type = get_tx_type_8x8(xd, (y_idx * 8 + x_idx) * 2);
          if (tx_type == DCT_DCT) {
            vp9_dequant_idct_add_8x8_c(xd->qcoeff + n * 64,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 4]);
          } else {
            vp9_ht_dequant_idct_add_8x8_c(tx_type, xd->qcoeff + n * 64,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n * 4]);
          }
        }
        for (n = 0; n < 4; n++) {
          const int x_idx = n & 1, y_idx = n >> 1;
          const int uv_offset = y_idx * 8 * xd->dst.uv_stride + x_idx * 8;
          vp9_dequant_idct_add_8x8_c(xd->qcoeff + n * 64 + 1024,
              xd->block[16].dequant,
              xd->dst.u_buffer + uv_offset,
              xd->dst.u_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[64 + n * 4]);
          vp9_dequant_idct_add_8x8_c(xd->qcoeff + n * 64 + 1280,
              xd->block[20].dequant,
              xd->dst.v_buffer + uv_offset,
              xd->dst.v_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[80 + n * 4]);
        }
        break;
      case TX_4X4:
        for (n = 0; n < 64; n++) {
          const int x_idx = n & 7, y_idx = n >> 3;
          const int y_offset = y_idx * 4 * xd->dst.y_stride + x_idx * 4;

          const TX_TYPE tx_type = get_tx_type_4x4(xd, y_idx * 8 + x_idx);
          if (tx_type == DCT_DCT) {
            xd->itxm_add(xd->qcoeff + n * 16, xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n]);
          } else {
            vp9_ht_dequant_idct_add_c(tx_type, xd->qcoeff + n * 16,
                xd->block[0].dequant,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_buffer + y_offset,
                xd->dst.y_stride, xd->dst.y_stride, xd->eobs[n]);
          }
        }

        for (n = 0; n < 16; n++) {
          const int x_idx = n & 3, y_idx = n >> 2;
          const int uv_offset = y_idx * 4 * xd->dst.uv_stride + x_idx * 4;
          xd->itxm_add(xd->qcoeff + 1024 + n * 16,
              xd->block[16].dequant,
              xd->dst.u_buffer + uv_offset,
              xd->dst.u_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[64 + n]);
          xd->itxm_add(xd->qcoeff + 1280 + n * 16,
              xd->block[20].dequant,
              xd->dst.v_buffer + uv_offset,
              xd->dst.v_buffer + uv_offset,
              xd->dst.uv_stride, xd->dst.uv_stride, xd->eobs[80 + n]);
        }
        break;
      default: assert(0);
    }
  }
}

static void decode_macroblock(VP9D_COMP *pbi, MACROBLOCKD *xd,
                              int mb_row, unsigned int mb_col,
                              BOOL_DECODER* const bc) {
  int eobtotal = 0;
  MB_PREDICTION_MODE mode;
  int tx_size;

  assert(!xd->mode_info_context->mbmi.sb_type);

  // re-initialize macroblock dequantizer before detokenization
  if (xd->segmentation_enabled)
    mb_init_dequantizer(pbi, xd);

  tx_size = xd->mode_info_context->mbmi.txfm_size;
  mode = xd->mode_info_context->mbmi.mode;

  if (xd->mode_info_context->mbmi.mb_skip_coeff) {
    vp9_reset_mb_tokens_context(xd);
  } else if (!bool_error(bc)) {
    if (mode != B_PRED)
      eobtotal = vp9_decode_mb_tokens(pbi, xd, bc);
  }

  //mode = xd->mode_info_context->mbmi.mode;