encodetxb.c

/*
 * Copyright (c) 2017, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 2 Clause License and
 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
 * was not distributed with this source code in the LICENSE file, you can
 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
 * Media Patent License 1.0 was not distributed with this source code in the
 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
 */

#include "aom_ports/mem.h"
#include "av1/common/scan.h"
#include "av1/common/blockd.h"
#include "av1/common/idct.h"
#include "av1/common/pred_common.h"
#include "av1/encoder/bitstream.h"
#include "av1/encoder/encodeframe.h"
#include "av1/encoder/cost.h"
#include "av1/encoder/encodetxb.h"
#include "av1/encoder/hash.h"
#include "av1/encoder/rdopt.h"
#include "av1/encoder/tokenize.h"

#define TEST_OPTIMIZE_TXB 0

static int hbt_hash_needs_init = 1;
static CRC_CALCULATOR crc_calculator;
static CRC_CALCULATOR crc_calculator2;
static const int HBT_HASH_EOB = 16;  // also the length in opt_qcoeff

typedef struct OptTxbQcoeff {
  uint32_t hbt_hash_match;
  double hits;
  tran_low_t opt_qcoeff[16];
} OptTxbQcoeff;

OptTxbQcoeff hbt_hash_table[65536][16];

typedef struct LevelDownStats {
  int update;
  tran_low_t low_qc;
  tran_low_t low_dqc;
  int64_t dist0;
  int rate;
  int rate_low;
  int64_t dist;
  int64_t dist_low;
  int64_t rd;
  int64_t rd_low;
  int64_t nz_rd;
  int64_t rd_diff;
  int cost_diff;
  int64_t dist_diff;
  int new_eob;
} LevelDownStats;

void av1_alloc_txb_buf(AV1_COMP *cpi) {
#if 0
  AV1_COMMON *cm = &cpi->common;
  int mi_block_size = 1 << MI_SIZE_LOG2;
  // TODO(angiebird): Make sure cm->subsampling_x/y is set correctly, and then
  // use precise buffer size according to cm->subsampling_x/y
  int pixel_stride = mi_block_size * cm->mi_cols;
  int pixel_height = mi_block_size * cm->mi_rows;
  int i;
  for (i = 0; i < MAX_MB_PLANE; ++i) {
    CHECK_MEM_ERROR(
        cm, cpi->tcoeff_buf[i],
        aom_malloc(sizeof(*cpi->tcoeff_buf[i]) * pixel_stride * pixel_height));
  }
#else
  AV1_COMMON *cm = &cpi->common;
  int size = ((cm->mi_rows >> cm->mib_size_log2) + 1) *
             ((cm->mi_cols >> cm->mib_size_log2) + 1);

  av1_free_txb_buf(cpi);
  // TODO(jingning): This should be further reduced.
  CHECK_MEM_ERROR(cm, cpi->coeff_buffer_base,
                  aom_malloc(sizeof(*cpi->coeff_buffer_base) * size));
#endif
}

void av1_free_txb_buf(AV1_COMP *cpi) {
#if 0
  int i;
  for (i = 0; i < MAX_MB_PLANE; ++i) {
    aom_free(cpi->tcoeff_buf[i]);
  }
#else
  aom_free(cpi->coeff_buffer_base);
#endif
}

void av1_set_coeff_buffer(const AV1_COMP *const cpi, MACROBLOCK *const x,
                          int mi_row, int mi_col) {
  int mib_size_log2 = cpi->common.mib_size_log2;
  int stride = (cpi->common.mi_cols >> mib_size_log2) + 1;
  int offset = (mi_row >> mib_size_log2) * stride + (mi_col >> mib_size_log2);
  CB_COEFF_BUFFER *coeff_buf = &cpi->coeff_buffer_base[offset];
  const int txb_offset = x->cb_offset / (TX_SIZE_W_MIN * TX_SIZE_H_MIN);
  for (int plane = 0; plane < MAX_MB_PLANE; ++plane) {
    x->mbmi_ext->tcoeff[plane] = coeff_buf->tcoeff[plane] + x->cb_offset;
    x->mbmi_ext->eobs[plane] = coeff_buf->eobs[plane] + txb_offset;
    x->mbmi_ext->txb_skip_ctx[plane] =
        coeff_buf->txb_skip_ctx[plane] + txb_offset;
    x->mbmi_ext->dc_sign_ctx[plane] =
        coeff_buf->dc_sign_ctx[plane] + txb_offset;
  }
}

static void write_golomb(aom_writer *w, int level) {
  int x = level + 1;
  int i = x;
  int length = 0;

  while (i) {
    i >>= 1;
    ++length;
  }
  assert(length > 0);

  for (i = 0; i < length - 1; ++i) aom_write_bit(w, 0);

  for (i = length - 1; i >= 0; --i) aom_write_bit(w, (x >> i) & 0x01);
}

static INLINE tran_low_t get_lower_coeff(tran_low_t qc) {
  if (qc == 0) {
    return 0;
  }
  return qc > 0 ? qc - 1 : qc + 1;
}

static INLINE tran_low_t qcoeff_to_dqcoeff(tran_low_t qc,
#if CONFIG_NEW_QUANT
                                           const tran_low_t *nq_dq,
#endif  // CONFIG_NEW_QUANT
                                           int dqv, int shift) {
  int sgn = qc < 0 ? -1 : 1;
#if CONFIG_NEW_QUANT
  int dqcoeff = av1_dequant_coeff_nuq(abs(qc), dqv, nq_dq, shift);
  return sgn * dqcoeff;
#endif  // CONFIG_NEW_QUANT

  return sgn * ((abs(qc) * dqv) >> shift);
}

static INLINE int64_t get_coeff_dist(tran_low_t tcoeff, tran_low_t dqcoeff,
                                     int shift) {
#if CONFIG_DAALA_TX
  int depth_shift = (TX_COEFF_DEPTH - 11) * 2;
  int depth_round = depth_shift > 1 ? (1 << (depth_shift - 1)) : 0;
  const int64_t diff = tcoeff - dqcoeff;
  const int64_t error = (diff * diff + depth_round) >> depth_shift;
  (void)shift;
#else
  const int64_t diff = (tcoeff - dqcoeff) * (1 << shift);
  const int64_t error = diff * diff;
#endif
  return error;
}

void av1_update_eob_context(int eob, int seg_eob, TX_SIZE tx_size,
                            TX_TYPE tx_type, PLANE_TYPE plane,
                            FRAME_CONTEXT *ec_ctx, FRAME_COUNTS *counts,
                            uint8_t allow_update_cdf) {
  int eob_extra, dummy;
  const int eob_pt = get_eob_pos_token(eob, &eob_extra);
  const int max_eob_pt = get_eob_pos_token(seg_eob, &dummy);
  TX_SIZE txs_ctx = get_txsize_entropy_ctx(tx_size);

  (void)max_eob_pt;
  const int eob_multi_size = txsize_log2_minus4[tx_size];
  const int eob_multi_ctx = (tx_type_to_class[tx_type] == TX_CLASS_2D) ? 0 : 1;

  switch (eob_multi_size) {
    case 0:
      ++counts->eob_multi16[plane][eob_multi_ctx][eob_pt - 1];
      if (allow_update_cdf)
        update_cdf(ec_ctx->eob_flag_cdf16[plane][eob_multi_ctx], eob_pt - 1, 5);
      break;
    case 1:
      ++counts->eob_multi32[plane][eob_multi_ctx][eob_pt - 1];
      if (allow_update_cdf)
        update_cdf(ec_ctx->eob_flag_cdf32[plane][eob_multi_ctx], eob_pt - 1, 6);
      break;
    case 2:
      ++counts->eob_multi64[plane][eob_multi_ctx][eob_pt - 1];
      if (allow_update_cdf)
        update_cdf(ec_ctx->eob_flag_cdf64[plane][eob_multi_ctx], eob_pt - 1, 7);
      break;
    case 3:
      ++counts->eob_multi128[plane][eob_multi_ctx][eob_pt - 1];
      if (allow_update_cdf)
        update_cdf(ec_ctx->eob_flag_cdf128[plane][eob_multi_ctx], eob_pt - 1,
                   8);
      break;
    case 4:
      ++counts->eob_multi256[plane][eob_multi_ctx][eob_pt - 1];
      if (allow_update_cdf)
        update_cdf(ec_ctx->eob_flag_cdf256[plane][eob_multi_ctx], eob_pt - 1,
                   9);
      break;
    case 5:
      ++counts->eob_multi512[plane][eob_multi_ctx][eob_pt - 1];
      if (allow_update_cdf)
        update_cdf(ec_ctx->eob_flag_cdf512[plane][eob_multi_ctx], eob_pt - 1,
                   10);
      break;
    case 6:
    default:
      ++counts->eob_multi1024[plane][eob_multi_ctx][eob_pt - 1];
      if (allow_update_cdf)
        update_cdf(ec_ctx->eob_flag_cdf1024[plane][eob_multi_ctx], eob_pt - 1,
                   11);
      break;
  }

  if (k_eob_offset_bits[eob_pt] > 0) {
    int eob_shift = k_eob_offset_bits[eob_pt] - 1;
    int bit = (eob_extra & (1 << eob_shift)) ? 1 : 0;
    counts->eob_extra[txs_ctx][plane][eob_pt][bit]++;
    if (allow_update_cdf)
      update_cdf(ec_ctx->eob_extra_cdf[txs_ctx][plane][eob_pt], bit, 2);
  }
}

static int get_eob_cost(int eob, int seg_eob,
                        const LV_MAP_EOB_COST *txb_eob_costs,
                        const LV_MAP_COEFF_COST *txb_costs, TX_TYPE tx_type) {
  int eob_extra, dummy;
  const int eob_pt = get_eob_pos_token(eob, &eob_extra);
  const int max_eob_pt = get_eob_pos_token(seg_eob, &dummy);
  int eob_cost = 0;
  (void)max_eob_pt;
  const int eob_multi_ctx = (tx_type_to_class[tx_type] == TX_CLASS_2D) ? 0 : 1;
  eob_cost = txb_eob_costs->eob_cost[eob_multi_ctx][eob_pt - 1];

  if (k_eob_offset_bits[eob_pt] > 0) {
    int eob_shift = k_eob_offset_bits[eob_pt] - 1;
    int bit = (eob_extra & (1 << eob_shift)) ? 1 : 0;
    eob_cost += txb_costs->eob_extra_cost[eob_pt][bit];
    for (int i = 1; i < k_eob_offset_bits[eob_pt]; i++) {
      eob_shift = k_eob_offset_bits[eob_pt] - 1 - i;
      bit = (eob_extra & (1 << eob_shift)) ? 1 : 0;
      eob_cost += av1_cost_bit(128, bit);
    }
  }
  return eob_cost;
}

static int get_coeff_cost(const tran_low_t qc, const int scan_idx,
                          const int is_eob, const TxbInfo *const txb_info,
                          const LV_MAP_COEFF_COST *const txb_costs,
                          const int coeff_ctx);

static void get_dist_cost_stats(LevelDownStats *const stats, const int scan_idx,
                                const int is_eob,
                                const LV_MAP_COEFF_COST *const txb_costs,
                                const TxbInfo *const txb_info,
                                int has_nz_tail) {
  const int16_t *const scan = txb_info->scan_order->scan;
  const int coeff_idx = scan[scan_idx];
  const tran_low_t qc = txb_info->qcoeff[coeff_idx];
  const uint8_t *const levels = txb_info->levels;
  stats->new_eob = -1;
  stats->update = 0;
  stats->rd_low = 0;
  stats->rd = 0;
  // TODO(mfo): explore if there's a better way to prevent compiler init
  // warnings
  stats->nz_rd = 0;
  stats->dist_low = 0;
  stats->rate_low = 0;
  stats->low_qc = 0;

  const tran_low_t tqc = txb_info->tcoeff[coeff_idx];
  const int dqv = txb_info->dequant[coeff_idx != 0];
#if CONFIG_NEW_QUANT
  const tran_low_t *nq_dequant_val = txb_info->nq_dequant_vals[coeff_idx != 0];
#endif  // CONFIG_NEW_QUANT

  const int coeff_ctx =
      get_nz_map_ctx(levels, coeff_idx, txb_info->bwl, txb_info->height,
                     scan_idx, is_eob, txb_info->tx_size, txb_info->tx_type);
  const int qc_cost =
      get_coeff_cost(qc, scan_idx, is_eob, txb_info, txb_costs, coeff_ctx);
  if (qc == 0) {
    stats->dist = 0;
    stats->rate = qc_cost;
    return;
  } else {
    const tran_low_t dqc = qcoeff_to_dqcoeff(qc,
#if CONFIG_NEW_QUANT
                                             nq_dequant_val,
#endif  // CONFIG_NEW_QUANT
                                             dqv, txb_info->shift);
    const int64_t dqc_dist = get_coeff_dist(tqc, dqc, txb_info->shift);

    // distortion difference when coefficient is quantized to 0
    const tran_low_t dqc0 = qcoeff_to_dqcoeff(0,
#if CONFIG_NEW_QUANT
                                              nq_dequant_val,
#endif  // CONFIG_NEW_QUANT
                                              dqv, txb_info->shift);

    stats->dist0 = get_coeff_dist(tqc, dqc0, txb_info->shift);
    stats->dist = dqc_dist - stats->dist0;
    stats->rate = qc_cost;
  }

  stats->rd = RDCOST(txb_info->rdmult, stats->rate, stats->dist);

  stats->low_qc = get_lower_coeff(qc);

  if (is_eob && stats->low_qc == 0) {
    stats->rd_low = stats->rd;  // disable selection of low_qc in this case.
  } else {
    if (stats->low_qc == 0) {
      stats->dist_low = 0;
    } else {
      stats->low_dqc = qcoeff_to_dqcoeff(stats->low_qc,
#if CONFIG_NEW_QUANT
                                         nq_dequant_val,
#endif  // CONFIG_NEW_QUANT
                                         dqv, txb_info->shift);
      const int64_t low_dqc_dist =
          get_coeff_dist(tqc, stats->low_dqc, txb_info->shift);
      stats->dist_low = low_dqc_dist - stats->dist0;
    }
    const int low_qc_cost = get_coeff_cost(stats->low_qc, scan_idx, is_eob,
                                           txb_info, txb_costs, coeff_ctx);
    stats->rate_low = low_qc_cost;
    stats->rd_low = RDCOST(txb_info->rdmult, stats->rate_low, stats->dist_low);
  }
  if ((has_nz_tail < 2) && ((scan_idx == txb_info->eob - 1) || !is_eob)) {
    (void)levels;
    const int coeff_ctx_temp =
        get_nz_map_ctx(levels, coeff_idx, txb_info->bwl, txb_info->height,
                       scan_idx, 1, txb_info->tx_size, txb_info->tx_type);
    const int qc_eob_cost =
        get_coeff_cost(qc, scan_idx, 1, txb_info, txb_costs, coeff_ctx_temp);
    int64_t rd_eob = RDCOST(txb_info->rdmult, qc_eob_cost, stats->dist);
    if (stats->low_qc != 0) {
      const int low_qc_eob_cost = get_coeff_cost(
          stats->low_qc, scan_idx, 1, txb_info, txb_costs, coeff_ctx_temp);
      int64_t rd_eob_low =
          RDCOST(txb_info->rdmult, low_qc_eob_cost, stats->dist_low);
      rd_eob = (rd_eob > rd_eob_low) ? rd_eob_low : rd_eob;
    }

    stats->nz_rd = AOMMIN(stats->rd_low, stats->rd) - rd_eob;
  }
}

static INLINE void update_qcoeff(const int coeff_idx, const tran_low_t qc,
                                 const TxbInfo *const txb_info) {
  txb_info->qcoeff[coeff_idx] = qc;
  txb_info->levels[get_padded_idx(coeff_idx, txb_info->bwl)] =
      (uint8_t)clamp(abs(qc), 0, INT8_MAX);
}

static INLINE void update_coeff(const int coeff_idx, const tran_low_t qc,
                                const TxbInfo *const txb_info) {
  update_qcoeff(coeff_idx, qc, txb_info);
  const int dqv = txb_info->dequant[coeff_idx != 0];
#if CONFIG_NEW_QUANT
  const tran_low_t *nq_dequant_val = txb_info->nq_dequant_vals[coeff_idx != 0];
#endif  // CONFIG_NEW_QUANT
  txb_info->dqcoeff[coeff_idx] = qcoeff_to_dqcoeff(qc,
#if CONFIG_NEW_QUANT
                                                   nq_dequant_val,
#endif  // CONFIG_NEW_QUANT
                                                   dqv, txb_info->shift);
}

static INLINE void av1_txb_init_levels(const tran_low_t *const coeff,
                                       const int width, const int height,
                                       uint8_t *const levels) {
  const int stride = width + TX_PAD_HOR;
  uint8_t *ls = levels;

  memset(levels - TX_PAD_TOP * stride, 0,
         sizeof(*levels) * TX_PAD_TOP * stride);
  memset(levels + stride * height, 0,
         sizeof(*levels) * (TX_PAD_BOTTOM * stride + TX_PAD_END));

  for (int i = 0; i < height; i++) {
    for (int j = 0; j < width; j++) {
      *ls++ = (uint8_t)clamp(abs(coeff[i * width + j]), 0, INT8_MAX);
    }
    for (int j = 0; j < TX_PAD_HOR; j++) {
      *ls++ = 0;
    }
  }
}

void av1_get_nz_map_contexts_c(const uint8_t *const levels,
                               const int16_t *const scan, const uint16_t eob,
                               const TX_SIZE tx_size, const TX_TYPE tx_type,
                               int8_t *const coeff_contexts) {
  const int bwl = get_txb_bwl(tx_size);
  const int height = get_txb_high(tx_size);
  for (int i = 0; i < eob; ++i) {
    const int pos = scan[i];
    coeff_contexts[pos] = get_nz_map_ctx(levels, pos, bwl, height, i,
                                         i == eob - 1, tx_size, tx_type);
  }
}

void av1_write_coeffs_txb(const AV1_COMMON *const cm, MACROBLOCKD *xd,
                          aom_writer *w, int blk_row, int blk_col, int plane,
                          TX_SIZE tx_size, const tran_low_t *tcoeff,
                          uint16_t eob, TXB_CTX *txb_ctx) {
  MB_MODE_INFO *mbmi = &xd->mi[0]->mbmi;
  const PLANE_TYPE plane_type = get_plane_type(plane);
  const TX_SIZE txs_ctx = get_txsize_entropy_ctx(tx_size);
  const TX_TYPE tx_type =
      av1_get_tx_type(plane_type, xd, blk_row, blk_col, tx_size);
  const SCAN_ORDER *const scan_order = get_scan(cm, tx_size, tx_type, mbmi);
  const int16_t *const scan = scan_order->scan;
  const int seg_eob = av1_get_max_eob(tx_size);
  int c;
  const int bwl = get_txb_bwl(tx_size);
  const int width = get_txb_wide(tx_size);
  const int height = get_txb_high(tx_size);
  int update_eob = -1;
  FRAME_CONTEXT *ec_ctx = xd->tile_ctx;
  uint8_t levels_buf[TX_PAD_2D];
  uint8_t *const levels = set_levels(levels_buf, width);
  DECLARE_ALIGNED(16, uint8_t, level_counts[MAX_TX_SQUARE]);
  DECLARE_ALIGNED(16, int8_t, coeff_contexts[MAX_TX_SQUARE]);

  aom_write_bin(w, eob == 0,
                ec_ctx->txb_skip_cdf[txs_ctx][txb_ctx->txb_skip_ctx], 2);
#if CONFIG_TXK_SEL
  if (plane == 0 && eob == 0) {
    assert(tx_type == DCT_DCT);
  }
#endif
  if (eob == 0) return;

  av1_txb_init_levels(tcoeff, width, height, levels);

#if CONFIG_TXK_SEL
  av1_write_tx_type(cm, xd, blk_row, blk_col, plane, tx_size, w);
#endif

  int eob_extra, dummy;
  const int eob_pt = get_eob_pos_token(eob, &eob_extra);
  const int max_eob_pt = get_eob_pos_token(seg_eob, &dummy);

  (void)max_eob_pt;
  const int eob_multi_size = txsize_log2_minus4[tx_size];
  const int eob_multi_ctx = (tx_type_to_class[tx_type] == TX_CLASS_2D) ? 0 : 1;
  switch (eob_multi_size) {
    case 0:
      aom_write_symbol(w, eob_pt - 1,
                       ec_ctx->eob_flag_cdf16[plane_type][eob_multi_ctx], 5);
      break;
    case 1:
      aom_write_symbol(w, eob_pt - 1,
                       ec_ctx->eob_flag_cdf32[plane_type][eob_multi_ctx], 6);
      break;
    case 2:
      aom_write_symbol(w, eob_pt - 1,
                       ec_ctx->eob_flag_cdf64[plane_type][eob_multi_ctx], 7);
      break;
    case 3:
      aom_write_symbol(w, eob_pt - 1,
                       ec_ctx->eob_flag_cdf128[plane_type][eob_multi_ctx], 8);
      break;
    case 4:
      aom_write_symbol(w, eob_pt - 1,
                       ec_ctx->eob_flag_cdf256[plane_type][eob_multi_ctx], 9);
      break;
    case 5:
      aom_write_symbol(w, eob_pt - 1,
                       ec_ctx->eob_flag_cdf512[plane_type][eob_multi_ctx], 10);
      break;
    default:
      aom_write_symbol(w, eob_pt - 1,
                       ec_ctx->eob_flag_cdf1024[plane_type][eob_multi_ctx], 11);
      break;
  }

  if (k_eob_offset_bits[eob_pt] > 0) {
    int eob_shift = k_eob_offset_bits[eob_pt] - 1;
    int bit = (eob_extra & (1 << eob_shift)) ? 1 : 0;
    aom_write_bin(w, bit, ec_ctx->eob_extra_cdf[txs_ctx][plane_type][eob_pt],
                  2);
    for (int i = 1; i < k_eob_offset_bits[eob_pt]; i++) {
      eob_shift = k_eob_offset_bits[eob_pt] - 1 - i;
      bit = (eob_extra & (1 << eob_shift)) ? 1 : 0;
      aom_write_bit(w, bit);
    }
  }

  av1_get_nz_map_contexts(levels, scan, eob, tx_size, tx_type, coeff_contexts);

  for (c = eob - 1; c >= 0; --c) {
    const int pos = scan[c];
    const int coeff_ctx = coeff_contexts[pos];
    const tran_low_t v = tcoeff[pos];

    if (c == eob - 1) {
      aom_write_symbol(
          w, AOMMIN(abs(v), 3) - 1,
          ec_ctx->coeff_base_eob_cdf[txs_ctx][plane_type][coeff_ctx], 3);
    } else {
      aom_write_symbol(w, AOMMIN(abs(v), 3),
                       ec_ctx->coeff_base_cdf[txs_ctx][plane_type][coeff_ctx],
                       4);
    }
  }
  update_eob = eob - 1;

  // Loop to code all signs in the transform block,
  // starting with the sign of DC (if applicable)
  for (c = 0; c < eob; ++c) {
    const tran_low_t v = tcoeff[scan[c]];
    const tran_low_t level = abs(v);
    const int sign = (v < 0) ? 1 : 0;
    if (level == 0) continue;

    if (c == 0) {
      aom_write_bin(w, sign,
                    ec_ctx->dc_sign_cdf[plane_type][txb_ctx->dc_sign_ctx], 2);
    } else {
      aom_write_bit(w, sign);
    }
  }

  if (update_eob >= 0) {
    for (c = update_eob; c >= 0; --c) {
      const int pos = scan[c];
      const tran_low_t level = abs(tcoeff[pos]);
      int idx;
      int ctx;

      if (level <= NUM_BASE_LEVELS) continue;

      // level is above 1.
      const int base_range = level - 1 - NUM_BASE_LEVELS;
#if USE_CAUSAL_BR_CTX
      ctx = get_br_ctx(levels, pos, bwl, level_counts[pos], tx_type);

#else
      ctx = get_br_ctx(levels, pos, bwl, level_counts[pos]);
#endif
      for (idx = 0; idx < COEFF_BASE_RANGE; idx += BR_CDF_SIZE - 1) {
        const int k = AOMMIN(base_range - idx, BR_CDF_SIZE - 1);
        aom_write_symbol(w, k,
#if 0
            ec_ctx->coeff_br_cdf[AOMMIN(txs_ctx, TX_16X16)][plane_type][ctx],
#else
                         ec_ctx->coeff_br_cdf[AOMMIN(txs_ctx, TX_32X32)]
                                             [plane_type][ctx],
#endif
                         BR_CDF_SIZE);
        if (k < BR_CDF_SIZE - 1) break;
      }
      if (base_range < COEFF_BASE_RANGE) continue;
      // use 0-th order Golomb code to handle the residual level.
      write_golomb(w,
                   abs(tcoeff[pos]) - COEFF_BASE_RANGE - 1 - NUM_BASE_LEVELS);
    }
  }
}

typedef struct encode_txb_args {
  const AV1_COMMON *cm;
  MACROBLOCK *x;
  aom_writer *w;
} ENCODE_TXB_ARGS;

static void write_coeffs_txb_wrap(const AV1_COMMON *cm, MACROBLOCK *x,
                                  aom_writer *w, int plane, int block,
                                  int blk_row, int blk_col, TX_SIZE tx_size) {
  MACROBLOCKD *xd = &x->e_mbd;
  tran_low_t *tcoeff = BLOCK_OFFSET(x->mbmi_ext->tcoeff[plane], block);
  uint16_t eob = x->mbmi_ext->eobs[plane][block];
  TXB_CTX txb_ctx = { x->mbmi_ext->txb_skip_ctx[plane][block],
                      x->mbmi_ext->dc_sign_ctx[plane][block] };
  av1_write_coeffs_txb(cm, xd, w, blk_row, blk_col, plane, tx_size, tcoeff, eob,
                       &txb_ctx);
}

void av1_write_coeffs_mb(const AV1_COMMON *const cm, MACROBLOCK *x, int mi_row,
                         int mi_col, aom_writer *w, int plane,
                         BLOCK_SIZE bsize) {
  MACROBLOCKD *xd = &x->e_mbd;
  const struct macroblockd_plane *const pd = &xd->plane[plane];
  const TX_SIZE tx_size = av1_get_tx_size(plane, xd);
  const int stepr = tx_size_high_unit[tx_size];
  const int stepc = tx_size_wide_unit[tx_size];
  const BLOCK_SIZE plane_bsize = get_plane_block_size(bsize, pd);
  int row, col;
  const int max_blocks_wide = max_block_wide(xd, plane_bsize, plane);
  const int max_blocks_high = max_block_high(xd, plane_bsize, plane);

  if (!is_chroma_reference(mi_row, mi_col, bsize, pd->subsampling_x,
                           pd->subsampling_y))
    return;

  int blk_row, blk_col;
  int block = 0;
  const int step = stepr * stepc;
  const BLOCK_SIZE max_unit_bsize = get_plane_block_size(BLOCK_64X64, pd);
  int mu_blocks_wide = block_size_wide[max_unit_bsize] >> tx_size_wide_log2[0];
  int mu_blocks_high = block_size_high[max_unit_bsize] >> tx_size_high_log2[0];
  mu_blocks_wide = AOMMIN(max_blocks_wide, mu_blocks_wide);
  mu_blocks_high = AOMMIN(max_blocks_high, mu_blocks_high);

  for (row = 0; row < max_blocks_high; row += mu_blocks_high) {
    const int unit_height = AOMMIN(mu_blocks_high + row, max_blocks_high);
    for (col = 0; col < max_blocks_wide; col += mu_blocks_wide) {
      const int unit_width = AOMMIN(mu_blocks_wide + col, max_blocks_wide);

      for (blk_row = row; blk_row < unit_height; blk_row += stepr) {
        for (blk_col = col; blk_col < unit_width; blk_col += stepc) {
          write_coeffs_txb_wrap(cm, x, w, plane, block, blk_row, blk_col,
                                tx_size);
          block += step;
        }
      }
    }
  }
}

static INLINE int get_br_cost(tran_low_t abs_qc, int ctx,
                              const int *coeff_lps) {
  const tran_low_t min_level = 1 + NUM_BASE_LEVELS;
  const tran_low_t max_level = 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE;
  (void)ctx;
  if (abs_qc >= min_level) {
    if (abs_qc >= max_level)
      return coeff_lps[COEFF_BASE_RANGE];  // COEFF_BASE_RANGE * cost0;
    else
      return coeff_lps[(abs_qc - min_level)];  //  * cost0 + cost1;
  } else {
    return 0;
  }
}

// Note: don't call this function when eob is 0.
int av1_cost_coeffs_txb(const AV1_COMMON *const cm, const MACROBLOCK *x,
                        const int plane, const int blk_row, const int blk_col,
                        const int block, const TX_SIZE tx_size,
                        const TXB_CTX *const txb_ctx) {
  const MACROBLOCKD *const xd = &x->e_mbd;
  const TX_SIZE txs_ctx = get_txsize_entropy_ctx(tx_size);
  const PLANE_TYPE plane_type = get_plane_type(plane);
  const TX_TYPE tx_type =
      av1_get_tx_type(plane_type, xd, blk_row, blk_col, tx_size);
  const MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
  const struct macroblock_plane *p = &x->plane[plane];
  const int eob = p->eobs[block];
  const tran_low_t *const qcoeff = BLOCK_OFFSET(p->qcoeff, block);
  int c, cost;
  const int txb_skip_ctx = txb_ctx->txb_skip_ctx;
  const int bwl = get_txb_bwl(tx_size);
  const int width = get_txb_wide(tx_size);
  const int height = get_txb_high(tx_size);
  const SCAN_ORDER *const scan_order = get_scan(cm, tx_size, tx_type, mbmi);
  const int16_t *const scan = scan_order->scan;
  uint8_t levels_buf[TX_PAD_2D];
  uint8_t *const levels = set_levels(levels_buf, width);
  DECLARE_ALIGNED(16, uint8_t, level_counts[MAX_TX_SQUARE]);
  DECLARE_ALIGNED(16, int8_t, coeff_contexts[MAX_TX_SQUARE]);
  const LV_MAP_COEFF_COST *const coeff_costs =
      &x->coeff_costs[txs_ctx][plane_type];

  const int eob_multi_size = txsize_log2_minus4[tx_size];
  const LV_MAP_EOB_COST *const eob_costs =
      &x->eob_costs[eob_multi_size][plane_type];
  // eob must be greater than 0 here.
  assert(eob > 0);
  cost = coeff_costs->txb_skip_cost[txb_skip_ctx][0];

  av1_txb_init_levels(qcoeff, width, height, levels);

#if CONFIG_TXK_SEL
  cost += av1_tx_type_cost(cm, x, xd, mbmi->sb_type, plane, tx_size, tx_type);
#endif

  const int seg_eob = av1_get_max_eob(tx_size);
  int eob_cost = get_eob_cost(eob, seg_eob, eob_costs, coeff_costs, tx_type);
  cost += eob_cost;

  av1_get_nz_map_contexts(levels, scan, eob, tx_size, tx_type, coeff_contexts);

  for (c = eob - 1; c >= 0; --c) {
    const int pos = scan[c];
    const tran_low_t v = qcoeff[pos];
    const int is_nz = (v != 0);
    const int level = abs(v);
    const int coeff_ctx = coeff_contexts[pos];
    if (c == eob - 1) {
      cost += coeff_costs->base_eob_cost[coeff_ctx][AOMMIN(level, 3) - 1];
    } else {
      cost += coeff_costs->base_cost[coeff_ctx][AOMMIN(level, 3)];
    }

    if (is_nz) {
      int sign = (v < 0) ? 1 : 0;

      // sign bit cost
      if (c == 0) {
        int dc_sign_ctx = txb_ctx->dc_sign_ctx;
        cost += coeff_costs->dc_sign_cost[dc_sign_ctx][sign];
      } else {
        cost += av1_cost_bit(128, sign);
      }
      if (level > NUM_BASE_LEVELS) {
        int ctx;
#if USE_CAUSAL_BR_CTX
        ctx = get_br_ctx(levels, pos, bwl, level_counts[pos], tx_type);
#else
        ctx = get_br_ctx(levels, pos, bwl, level_counts[pos]);
#endif
        const int base_range = level - 1 - NUM_BASE_LEVELS;
        if (base_range < COEFF_BASE_RANGE) {
          cost += coeff_costs->lps_cost[ctx][base_range];
        } else {
          cost += coeff_costs->lps_cost[ctx][COEFF_BASE_RANGE];
        }

        if (level >= 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE) {
          // residual cost
          int r = level - COEFF_BASE_RANGE - NUM_BASE_LEVELS;
          int ri = r;
          int length = 0;

          while (ri) {
            ri >>= 1;
            ++length;
          }

          for (ri = 0; ri < length - 1; ++ri) cost += av1_cost_bit(128, 0);

          for (ri = length - 1; ri >= 0; --ri)
            cost += av1_cost_bit(128, (r >> ri) & 0x01);
        }
      }
    }
  }
  return cost;
}

static INLINE int has_base(tran_low_t qc, int base_idx) {
  const int level = base_idx + 1;
  return abs(qc) >= level;
}

static INLINE int has_br(tran_low_t qc) {
  return abs(qc) >= 1 + NUM_BASE_LEVELS;
}

static INLINE int get_sign_bit_cost(tran_low_t qc, int coeff_idx,
                                    const int (*dc_sign_cost)[2],
                                    int dc_sign_ctx) {
  const int sign = (qc < 0) ? 1 : 0;
  // sign bit cost
  if (coeff_idx == 0) {
    return dc_sign_cost[dc_sign_ctx][sign];
  } else {
    return av1_cost_bit(128, sign);
  }
}
static INLINE int get_golomb_cost(int abs_qc) {
  if (abs_qc >= 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE) {
    // residual cost
    int r = abs_qc - COEFF_BASE_RANGE - NUM_BASE_LEVELS;
    int ri = r;
    int length = 0;

    while (ri) {
      ri >>= 1;
      ++length;
    }

    return av1_cost_literal(2 * length - 1);
  } else {
    return 0;
  }
}

void gen_txb_cache(TxbCache *txb_cache, TxbInfo *txb_info) {
  // gen_nz_count_arr
  const int16_t *const scan = txb_info->scan_order->scan;
  const int bwl = txb_info->bwl;
  const int height = txb_info->height;
  const tran_low_t *const qcoeff = txb_info->qcoeff;
  const uint8_t *const levels = txb_info->levels;
  const BASE_CTX_TABLE *base_ctx_table =
      txb_info->coeff_ctx_table->base_ctx_table;
  for (int c = 0; c < txb_info->eob; ++c) {
    const int coeff_idx = scan[c];  // raster order
    const int row = coeff_idx >> bwl;
    const int col = coeff_idx - (row << bwl);

    txb_cache->nz_count_arr[coeff_idx] =
        get_nz_count(levels + get_padded_idx(coeff_idx, bwl), bwl,
                     tx_type_to_class[txb_info->tx_type]);

    txb_cache->nz_ctx_arr[coeff_idx] =
        get_nz_map_ctx_from_stats(0, coeff_idx, bwl, txb_info->tx_size,
                                  tx_type_to_class[txb_info->tx_type]);

    // gen_base_count_mag_arr
    if (!has_base(qcoeff[coeff_idx], 0)) continue;
    int *base_mag = txb_cache->base_mag_arr[coeff_idx];
    int count[NUM_BASE_LEVELS];
    get_base_count_mag(base_mag, count, qcoeff, bwl, height, row, col);

    for (int i = 0; i < NUM_BASE_LEVELS; ++i) {
      if (!has_base(qcoeff[coeff_idx], i)) break;
      txb_cache->base_count_arr[i][coeff_idx] = count[i];
      const int level = i + 1;
      txb_cache->base_ctx_arr[i][coeff_idx] =
          base_ctx_table[row != 0][col != 0][base_mag[0] > level][count[i]];
    }

    // gen_br_count_mag_arr
    if (!has_br(qcoeff[coeff_idx])) continue;
    int *br_count = txb_cache->br_count_arr + coeff_idx;
    int *br_mag = txb_cache->br_mag_arr[coeff_idx];
    *br_count = get_br_count_mag(br_mag, qcoeff, bwl, height, row, col,
                                 NUM_BASE_LEVELS);
    txb_cache->br_ctx_arr[coeff_idx] =
        get_br_ctx_from_count_mag(row, col, *br_count, br_mag[0]);
  }
}

static INLINE const int *get_level_prob(int level, int coeff_idx,
                                        const TxbCache *txb_cache,
                                        const LV_MAP_COEFF_COST *txb_costs) {
  if (level < 1 + NUM_BASE_LEVELS) {
    const int ctx = txb_cache->nz_ctx_arr[coeff_idx];
    return &txb_costs->base_cost[ctx][level];
  } else if (level >= 1 + NUM_BASE_LEVELS &&
             level < 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE) {
    const int ctx = txb_cache->br_ctx_arr[coeff_idx];
    return txb_costs->lps_cost[ctx];
  } else if (level >= 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE) {
    // printf("get_level_prob does not support golomb\n");
    assert(0);
    return 0;
  } else {
    assert(0);
    return 0;
  }
}

static INLINE void update_mag_arr(int *mag_arr, int abs_qc) {
  if (mag_arr[0] == abs_qc) {
    mag_arr[1] -= 1;
    assert(mag_arr[1] >= 0);
  }
}

static INLINE int get_mag_from_mag_arr(const int *mag_arr) {
  int mag;
  if (mag_arr[1] > 0) {
    mag = mag_arr[0];
  } else if (mag_arr[0] > 0) {
    mag = mag_arr[0] - 1;
  } else {
    // no neighbor
    assert(mag_arr[0] == 0 && mag_arr[1] == 0);
    mag = 0;
  }
  return mag;
}

static int neighbor_level_down_update(int *new_count, int *new_mag, int count,
                                      const int *mag, int coeff_idx,
                                      tran_low_t abs_nb_coeff, int nb_coeff_idx,
                                      int level, const TxbInfo *txb_info) {
  *new_count = count;
  *new_mag = get_mag_from_mag_arr(mag);

  int update = 0;
  // check if br_count changes
  if (abs_nb_coeff == level) {
    update = 1;
    *new_count -= 1;
    assert(*new_count >= 0);
  }
  const int row = coeff_idx >> txb_info->bwl;
  const int col = coeff_idx - (row << txb_info->bwl);
  const int nb_row = nb_coeff_idx >> txb_info->bwl;
  const int nb_col = nb_coeff_idx - (nb_row << txb_info->bwl);

  // check if mag changes
  if (nb_row >= row && nb_col >= col) {
    if (abs_nb_coeff == mag[0]) {
      assert(mag[1] > 0);
      if (mag[1] == 1) {
        // the nb is the only qc with max mag
        *new_mag -= 1;
        assert(*new_mag >= 0);
        update = 1;
      }
    }
  }
  return update;
}

static int try_neighbor_level_down_br(int coeff_idx, int nb_coeff_idx,
                                      const TxbCache *txb_cache,
                                      const LV_MAP_COEFF_COST *txb_costs,
                                      const TxbInfo *txb_info) {
  const tran_low_t qc = txb_info->qcoeff[coeff_idx];
  const tran_low_t abs_qc = abs(qc);
  const int level = NUM_BASE_LEVELS + 1;
  if (abs_qc < level) return 0;

  const tran_low_t nb_coeff = txb_info->qcoeff[nb_coeff_idx];
  const tran_low_t abs_nb_coeff = abs(nb_coeff);
  const int count = txb_cache->br_count_arr[coeff_idx];
  const int *mag = txb_cache->br_mag_arr[coeff_idx];
  int new_count;
  int new_mag;
  const int update =
      neighbor_level_down_update(&new_count, &new_mag, count, mag, coeff_idx,
                                 abs_nb_coeff, nb_coeff_idx, level, txb_info);
  if (update) {
    const int row = coeff_idx >> txb_info->bwl;
    const int col = coeff_idx - (row << txb_info->bwl);
    const int ctx = txb_cache->br_ctx_arr[coeff_idx];
    const int org_cost = get_br_cost(abs_qc, ctx, txb_costs->lps_cost[ctx]);

    const int new_ctx = get_br_ctx_from_count_mag(row, col, new_count, new_mag);
    const int new_cost =
        get_br_cost(abs_qc, new_ctx, txb_costs->lps_cost[new_ctx]);
    const int cost_diff = -org_cost + new_cost;
    return cost_diff;
  } else {
    return 0;
  }
}

static int try_neighbor_level_down_base(int coeff_idx, int nb_coeff_idx,
                                        const TxbCache *txb_cache,
                                        const LV_MAP_COEFF_COST *txb_costs,
                                        const TxbInfo *txb_info) {
  // TODO(olah): not implemented yet
  (void)coeff_idx;
  (void)nb_coeff_idx;
  (void)txb_cache;
  (void)txb_costs;
  (void)txb_info;
  return 0;
}

static int try_neighbor_level_down_nz(int coeff_idx, int nb_coeff_idx,
                                      const TxbCache *txb_cache,
                                      const LV_MAP_COEFF_COST *txb_costs,
                                      TxbInfo *txb_info) {
  // assume eob doesn't change
  const tran_low_t qc = txb_info->qcoeff[coeff_idx];
  const tran_low_t abs_qc = abs(qc);
  const tran_low_t nb_coeff = txb_info->qcoeff[nb_coeff_idx];
  const tran_low_t abs_nb_coeff = abs(nb_coeff);
  if (abs_nb_coeff != 1) return 0;
  const int16_t *const iscan = txb_info->scan_order->iscan;
  const int scan_idx = iscan[coeff_idx];
  if (scan_idx == txb_info->seg_eob) return 0;
  const int nb_scan_idx = iscan[nb_coeff_idx];
  if (nb_scan_idx < scan_idx) {
    const int count = txb_cache->nz_count_arr[coeff_idx];
    (void)count;
    assert(count > 0);
    update_qcoeff(nb_coeff_idx, get_lower_coeff(nb_coeff), txb_info);
    const int new_ctx = get_nz_map_ctx_from_stats(
        0, coeff_idx, txb_info->bwl, txb_info->tx_size,
        tx_type_to_class[txb_info->tx_type]);
    update_qcoeff(nb_coeff_idx, nb_coeff, txb_info);
    const int ctx = txb_cache->nz_ctx_arr[coeff_idx];
    const int org_cost = txb_costs->base_cost[ctx][AOMMIN(abs_qc, 3)];
    const int new_cost = txb_costs->base_cost[new_ctx][AOMMIN(abs_qc, 3)];
    const int cost_diff = new_cost - org_cost;
    return cost_diff;
  } else {
    return 0;
  }
}

static int try_self_level_down(tran_low_t *low_coeff, int coeff_idx,
                               const TxbCache *txb_cache,
                               const LV_MAP_COEFF_COST *txb_costs,
                               TxbInfo *txb_info) {
  const tran_low_t qc = txb_info->qcoeff[coeff_idx];
  if (qc == 0) {
    *low_coeff = 0;
    return 0;
  }
  const tran_low_t abs_qc = abs(qc);
  *low_coeff = get_lower_coeff(qc);
  int cost_diff;
  if (*low_coeff == 0) {
    const int scan_idx = txb_info->scan_order->iscan[coeff_idx];
    const int *level_cost =
        get_level_prob(abs_qc, coeff_idx, txb_cache, txb_costs);
    const int *low_level_cost =
        get_level_prob(abs(*low_coeff), coeff_idx, txb_cache, txb_costs);

    if (scan_idx < txb_info->eob - 1) {
      // When level-0, we code the binary of abs_qc > level
      // but when level-k k > 0 we code the binary of abs_qc == level
      // That's why wee need this special treatment for level-0 map
      // TODO(angiebird): make leve-0 consistent to other levels
      cost_diff = -level_cost[1] + low_level_cost[0] - low_level_cost[1];
    } else {
      cost_diff = -level_cost[1];
    }

    const int sign_cost = get_sign_bit_cost(
        qc, coeff_idx, txb_costs->dc_sign_cost, txb_info->txb_ctx->dc_sign_ctx);
    cost_diff -= sign_cost;
  } else if (abs_qc <= NUM_BASE_LEVELS) {
    const int *level_cost =
        get_level_prob(abs_qc, coeff_idx, txb_cache, txb_costs);
    const int *low_level_cost =
        get_level_prob(abs(*low_coeff), coeff_idx, txb_cache, txb_costs);
    cost_diff = -level_cost[1] + low_level_cost[1] - low_level_cost[0];
  } else if (abs_qc == NUM_BASE_LEVELS + 1) {
    const int *level_cost =
        get_level_prob(abs_qc, coeff_idx, txb_cache, txb_costs);
    const int *low_level_cost =
        get_level_prob(abs(*low_coeff), coeff_idx, txb_cache, txb_costs);
    cost_diff = -level_cost[0] + low_level_cost[1] - low_level_cost[0];
  } else if (abs_qc < 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE) {
    const int *level_cost =
        get_level_prob(abs_qc, coeff_idx, txb_cache, txb_costs);
    const int *low_level_cost =
        get_level_prob(abs(*low_coeff), coeff_idx, txb_cache, txb_costs);

    cost_diff = -level_cost[abs_qc - 1 - NUM_BASE_LEVELS] +
                low_level_cost[abs(*low_coeff) - 1 - NUM_BASE_LEVELS];
  } else if (abs_qc == 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE) {
    const int *low_level_cost =
        get_level_prob(abs(*low_coeff), coeff_idx, txb_cache, txb_costs);
    cost_diff = -get_golomb_cost(abs_qc) - low_level_cost[COEFF_BASE_RANGE] +
                low_level_cost[COEFF_BASE_RANGE - 1];
  } else {
    assert(abs_qc > 1 + NUM_BASE_LEVELS + COEFF_BASE_RANGE);
    const tran_low_t abs_low_coeff = abs(*low_coeff);
    cost_diff = -get_golomb_cost(abs_qc) + get_golomb_cost(abs_low_coeff);
  }
  return cost_diff;
}

#define COST_MAP_SIZE 5
#define COST_MAP_OFFSET 2

static INLINE int check_nz_neighbor(tran_low_t qc) { return abs(qc) == 1; }

static INLINE int check_base_neighbor(tran_low_t qc) {
  return abs(qc) <= 1 + NUM_BASE_LEVELS;
}

static INLINE int check_br_neighbor(tran_low_t qc) {
  return abs(qc) > BR_MAG_OFFSET;
}

#define FAST_OPTIMIZE_TXB 1

#if FAST_OPTIMIZE_TXB
#define ALNB_REF_OFFSET_NUM 2
static const int alnb_ref_offset[ALNB_REF_OFFSET_NUM][2] = {
  { -1, 0 }, { 0, -1 },
};
#define NB_REF_OFFSET_NUM 4
static const int nb_ref_offset[NB_REF_OFFSET_NUM][2] = {
  { -1, 0 }, { 0, -1 }, { 1, 0 }, { 0, 1 },
};
#endif  // FAST_OPTIMIZE_TXB

// TODO(angiebird): add static to this function once it's called
int try_level_down(int coeff_idx, const TxbCache *txb_cache,
                   const LV_MAP_COEFF_COST *txb_costs, TxbInfo *txb_info,
                   int (*cost_map)[COST_MAP_SIZE], int fast_mode) {
#if !FAST_OPTIMIZE_TXB
  (void)fast_mode;
#endif