av1/common/txb_common.h

/*
 * 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.
 */

#ifndef AV1_COMMON_TXB_COMMON_H_
#define AV1_COMMON_TXB_COMMON_H_
extern const int16_t av1_coeff_band_4x4[16];

extern const int16_t av1_coeff_band_8x8[64];

extern const int16_t av1_coeff_band_16x16[256];

extern const int16_t av1_coeff_band_32x32[1024];

typedef struct txb_ctx {
  int txb_skip_ctx;
  int dc_sign_ctx;
} TXB_CTX;

static INLINE TX_SIZE get_txsize_context(TX_SIZE tx_size) {
  return txsize_sqr_up_map[tx_size];
}

#define BASE_CONTEXT_POSITION_NUM 12
static int base_ref_offset[BASE_CONTEXT_POSITION_NUM][2] = {
  /* clang-format off*/
  { -2, 0 }, { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -2 }, { 0, -1 }, { 0, 1 },
  { 0, 2 },  { 1, -1 },  { 1, 0 },  { 1, 1 },  { 2, 0 }
  /* clang-format on*/
};

static INLINE int get_level_count(const tran_low_t *tcoeffs, int stride,
                                  int height, int row, int col, int level,
                                  int (*nb_offset)[2], int nb_num) {
  int count = 0;
  for (int idx = 0; idx < nb_num; ++idx) {
    const int ref_row = row + nb_offset[idx][0];
    const int ref_col = col + nb_offset[idx][1];
    const int pos = ref_row * stride + ref_col;
    if (ref_row < 0 || ref_col < 0 || ref_row >= height || ref_col >= stride)
      continue;
    tran_low_t abs_coeff = abs(tcoeffs[pos]);
    count += abs_coeff > level;
  }
  return count;
}

static INLINE void get_mag(int *mag, const tran_low_t *tcoeffs, int stride,
                           int height, int row, int col, int (*nb_offset)[2],
                           int nb_num) {
  mag[0] = 0;
  mag[1] = 0;
  for (int idx = 0; idx < nb_num; ++idx) {
    const int ref_row = row + nb_offset[idx][0];
    const int ref_col = col + nb_offset[idx][1];
    const int pos = ref_row * stride + ref_col;
    if (ref_row < 0 || ref_col < 0 || ref_row >= height || ref_col >= stride)
      continue;
    tran_low_t abs_coeff = abs(tcoeffs[pos]);
    if (nb_offset[idx][0] >= 0 && nb_offset[idx][1] >= 0) {
      if (abs_coeff > mag[0]) {
        mag[0] = abs_coeff;
        mag[1] = 1;
      } else if (abs_coeff == mag[0]) {
        ++mag[1];
      }
    }
  }
}
static INLINE int get_level_count_mag(int *mag, const tran_low_t *tcoeffs,
                                      int stride, int height, int row, int col,
                                      int level, int (*nb_offset)[2],
                                      int nb_num) {
  int count = 0;
  *mag = 0;
  for (int idx = 0; idx < nb_num; ++idx) {
    const int ref_row = row + nb_offset[idx][0];
    const int ref_col = col + nb_offset[idx][1];
    const int pos = ref_row * stride + ref_col;
    if (ref_row < 0 || ref_col < 0 || ref_row >= height || ref_col >= stride)
      continue;
    tran_low_t abs_coeff = abs(tcoeffs[pos]);
    count += abs_coeff > level;
    if (nb_offset[idx][0] >= 0 && nb_offset[idx][1] >= 0)
      *mag = AOMMAX(*mag, abs_coeff);
  }
  return count;
}

static INLINE int get_base_ctx_from_count_mag(int row, int col, int count,
                                              int mag, int level) {
  const int ctx = (count + 1) >> 1;
  const int sig_mag = mag > level;
  int ctx_idx = -1;
  if (row == 0 && col == 0) {
    ctx_idx = (ctx << 1) + sig_mag;
    assert(ctx_idx < 8);
  } else if (row == 0) {
    ctx_idx = 8 + (ctx << 1) + sig_mag;
    assert(ctx_idx < 18);
  } else if (col == 0) {
    ctx_idx = 8 + 10 + (ctx << 1) + sig_mag;
    assert(ctx_idx < 28);
  } else {
    ctx_idx = 8 + 10 + 10 + (ctx << 1) + sig_mag;
    assert(ctx_idx < COEFF_BASE_CONTEXTS);
  }
  return ctx_idx;
}

static INLINE int get_base_ctx(const tran_low_t *tcoeffs,
                               int c,  // raster order
                               const int bwl, const int height,
                               const int level) {
  const int stride = 1 << bwl;
  const int row = c >> bwl;
  const int col = c - (row << bwl);
  const int level_minus_1 = level - 1;
  int mag;
  int count = get_level_count_mag(&mag, tcoeffs, stride, height, row, col,
                                  level_minus_1, base_ref_offset,
                                  BASE_CONTEXT_POSITION_NUM);
  int ctx_idx = get_base_ctx_from_count_mag(row, col, count, mag, level);
  return ctx_idx;
}

#define BR_CONTEXT_POSITION_NUM 8  // Base range coefficient context
static int br_ref_offset[BR_CONTEXT_POSITION_NUM][2] = {
  /* clang-format off*/
  { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 },
  { 0, 1 },   { 1, -1 }, { 1, 0 },  { 1, 1 },
  /* clang-format on*/
};

static int br_level_map[9] = {
  0, 0, 1, 1, 2, 2, 3, 3, 3,
};

#define BR_MAG_OFFSET 1
// TODO(angiebird): optimize this function by using a table to map from
// count/mag to ctx
static INLINE int get_br_ctx_from_count_mag(int row, int col, int count,
                                            int mag) {
  int offset = 0;
  if (mag <= BR_MAG_OFFSET)
    offset = 0;
  else if (mag <= 3)
    offset = 1;
  else if (mag <= 6)
    offset = 2;
  else
    offset = 3;

  int ctx = br_level_map[count];
  ctx += offset * BR_TMP_OFFSET;

  // DC: 0 - 1
  if (row == 0 && col == 0) return ctx;

  // Top row: 2 - 4
  if (row == 0) return 2 + ctx;

  // Left column: 5 - 7
  if (col == 0) return 5 + ctx;

  // others: 8 - 11
  return 8 + ctx;
}

static INLINE int get_br_ctx(const tran_low_t *tcoeffs,
                             const int c,  // raster order
                             const int bwl, const int height) {
  const int stride = 1 << bwl;
  const int row = c >> bwl;
  const int col = c - (row << bwl);
  const int level_minus_1 = NUM_BASE_LEVELS;
  int mag;
  const int count = get_level_count_mag(&mag, tcoeffs, stride, height, row, col,
                                        level_minus_1, br_ref_offset,
                                        BR_CONTEXT_POSITION_NUM);
  const int ctx = get_br_ctx_from_count_mag(row, col, count, mag);
  return ctx;
}

#define SIG_REF_OFFSET_NUM 11
static int sig_ref_offset[SIG_REF_OFFSET_NUM][2] = {
  { -2, -1 }, { -2, 0 }, { -2, 1 }, { -1, -2 }, { -1, -1 }, { -1, 0 },
  { -1, 1 },  { 0, -2 }, { 0, -1 }, { 1, -2 },  { 1, -1 },
};

static INLINE int get_nz_map_ctx(const tran_low_t *tcoeffs,
                                 const uint8_t *txb_mask,
                                 const int coeff_idx,  // raster order
                                 const int bwl, const int height) {
  const int row = coeff_idx >> bwl;
  const int col = coeff_idx - (row << bwl);
  int ctx = 0;
  int idx;
  int stride = 1 << bwl;

  if (row == 0 && col == 0) return 0;

  if (row == 0 && col == 1) return 1 + (tcoeffs[0] != 0);

  if (row == 1 && col == 0) return 3 + (tcoeffs[0] != 0);

  if (row == 1 && col == 1) {
    int pos;
    ctx = (tcoeffs[0] != 0);

    if (txb_mask[1]) ctx += (tcoeffs[1] != 0);
    pos = 1 << bwl;
    if (txb_mask[pos]) ctx += (tcoeffs[pos] != 0);

    ctx = (ctx + 1) >> 1;

    assert(5 + ctx <= 7);

    return 5 + ctx;
  }

  for (idx = 0; idx < SIG_REF_OFFSET_NUM; ++idx) {
    int ref_row = row + sig_ref_offset[idx][0];
    int ref_col = col + sig_ref_offset[idx][1];
    int pos;

    if (ref_row < 0 || ref_col < 0 || ref_row >= height || ref_col >= stride)
      continue;

    pos = (ref_row << bwl) + ref_col;

    if (txb_mask[pos]) ctx += (tcoeffs[pos] != 0);
  }

  if (row == 0) {
    ctx = (ctx + 1) >> 1;

    assert(ctx < 3);
    return 8 + ctx;
  }

  if (col == 0) {
    ctx = (ctx + 1) >> 1;

    assert(ctx < 3);
    return 11 + ctx;
  }

  ctx >>= 1;

  assert(14 + ctx < 20);

  return 14 + ctx;
}

static INLINE int get_nz_count(const tran_low_t *tcoeffs, int stride,
                               int height, int row, int col,
                               const int16_t *iscan) {
  int count = 0;
  const int pos = row * stride + col;
  for (int idx = 0; idx < SIG_REF_OFFSET_NUM; ++idx) {
    const int ref_row = row + sig_ref_offset[idx][0];
    const int ref_col = col + sig_ref_offset[idx][1];
    if (ref_row < 0 || ref_col < 0 || ref_row >= height || ref_col >= stride)
      continue;
    const int nb_pos = ref_row * stride + ref_col;
    if (iscan[nb_pos] < iscan[pos]) count += (tcoeffs[nb_pos] != 0);
  }
  return count;
}

// TODO(angiebird): optimize this function by generate a table that maps from
// count to ctx
static INLINE int get_nz_map_ctx_from_count(int count,
                                            const tran_low_t *tcoeffs,
                                            int coeff_idx,  // raster order
                                            int bwl, const int16_t *iscan) {
  const int row = coeff_idx >> bwl;
  const int col = coeff_idx - (row << bwl);
  int ctx = 0;

  if (row == 0 && col == 0) return 0;

  if (row == 0 && col == 1) return 1 + (tcoeffs[0] != 0);

  if (row == 1 && col == 0) return 3 + (tcoeffs[0] != 0);

  if (row == 1 && col == 1) {
    int pos;
    ctx = (tcoeffs[0] != 0);

    if (iscan[1] < iscan[coeff_idx]) ctx += (tcoeffs[1] != 0);
    pos = 1 << bwl;
    if (iscan[pos] < iscan[coeff_idx]) ctx += (tcoeffs[pos] != 0);

    ctx = (ctx + 1) >> 1;

    assert(5 + ctx <= 7);

    return 5 + ctx;
  }

  if (row == 0) {
    ctx = (count + 1) >> 1;

    assert(ctx < 3);
    return 8 + ctx;
  }

  if (col == 0) {
    ctx = (count + 1) >> 1;

    assert(ctx < 3);
    return 11 + ctx;
  }

  ctx = count >> 1;

  assert(14 + ctx < 20);

  return 14 + ctx;
}

// TODO(angiebird): merge this function with get_nz_map_ctx() after proper
// testing
static INLINE int get_nz_map_ctx2(const tran_low_t *tcoeffs,
                                  const int coeff_idx,  // raster order
                                  const int bwl, const int height,
                                  const int16_t *iscan) {
  int stride = 1 << bwl;
  const int row = coeff_idx >> bwl;
  const int col = coeff_idx - (row << bwl);
  int count = get_nz_count(tcoeffs, stride, height, row, col, iscan);
  return get_nz_map_ctx_from_count(count, tcoeffs, coeff_idx, bwl, iscan);
}

static INLINE int get_eob_ctx(const tran_low_t *tcoeffs,
                              const int coeff_idx,  // raster order
                              const TX_SIZE txs_ctx) {
  (void)tcoeffs;
  if (txs_ctx == TX_4X4) return av1_coeff_band_4x4[coeff_idx];
  if (txs_ctx == TX_8X8) return av1_coeff_band_8x8[coeff_idx];
  if (txs_ctx == TX_16X16) return av1_coeff_band_16x16[coeff_idx];
  if (txs_ctx == TX_32X32) return av1_coeff_band_32x32[coeff_idx];

  assert(0);
  return 0;
}

static INLINE void set_dc_sign(int *cul_level, tran_low_t v) {
  if (v < 0)
    *cul_level |= 1 << COEFF_CONTEXT_BITS;
  else if (v > 0)
    *cul_level += 2 << COEFF_CONTEXT_BITS;
}

static INLINE int get_dc_sign_ctx(int dc_sign) {
  int dc_sign_ctx = 0;
  if (dc_sign < 0)
    dc_sign_ctx = 1;
  else if (dc_sign > 0)
    dc_sign_ctx = 2;

  return dc_sign_ctx;
}

static INLINE void get_txb_ctx(BLOCK_SIZE plane_bsize, TX_SIZE tx_size,
                               int plane, const ENTROPY_CONTEXT *a,
                               const ENTROPY_CONTEXT *l, TXB_CTX *txb_ctx) {
  const int txb_w_unit = tx_size_wide_unit[tx_size];
  const int txb_h_unit = tx_size_high_unit[tx_size];
  int ctx_offset = (plane == 0) ? 0 : 7;

  if (plane_bsize > txsize_to_bsize[tx_size]) ctx_offset += 3;

  int dc_sign = 0;
  for (int k = 0; k < txb_w_unit; ++k) {
    int sign = ((uint8_t)a[k]) >> COEFF_CONTEXT_BITS;
    if (sign == 1)
      --dc_sign;
    else if (sign == 2)
      ++dc_sign;
    else if (sign != 0)
      assert(0);
  }

  for (int k = 0; k < txb_h_unit; ++k) {
    int sign = ((uint8_t)l[k]) >> COEFF_CONTEXT_BITS;
    if (sign == 1)
      --dc_sign;
    else if (sign == 2)
      ++dc_sign;
    else if (sign != 0)
      assert(0);
  }

  txb_ctx->dc_sign_ctx = get_dc_sign_ctx(dc_sign);

  if (plane == 0) {
    int top = 0;
    int left = 0;

    for (int k = 0; k < txb_w_unit; ++k) {
      top = AOMMAX(top, ((uint8_t)a[k] & COEFF_CONTEXT_MASK));
    }

    for (int k = 0; k < txb_h_unit; ++k) {
      left = AOMMAX(left, ((uint8_t)l[k] & COEFF_CONTEXT_MASK));
    }

    top = AOMMIN(top, 255);
    left = AOMMIN(left, 255);

    if (plane_bsize == txsize_to_bsize[tx_size])
      txb_ctx->txb_skip_ctx = 0;
    else if (top == 0 && left == 0)
      txb_ctx->txb_skip_ctx = 1;
    else if (top == 0 || left == 0)
      txb_ctx->txb_skip_ctx = 2 + (AOMMAX(top, left) > 3);
    else if (AOMMAX(top, left) <= 3)
      txb_ctx->txb_skip_ctx = 4;
    else if (AOMMIN(top, left) <= 3)
      txb_ctx->txb_skip_ctx = 5;
    else
      txb_ctx->txb_skip_ctx = 6;
  } else {
    int ctx_base = get_entropy_context(tx_size, a, l);
    txb_ctx->txb_skip_ctx = ctx_offset + ctx_base;
  }
}

void av1_adapt_txb_probs(AV1_COMMON *cm, unsigned int count_sat,
                         unsigned int update_factor);
#endif  // AV1_COMMON_TXB_COMMON_H_