text: /*
   * Copyright (c) 2016, 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 "av1/common/common.h"
  #include "av1/common/pred_common.h"
  #include "av1/common/reconinter.h"
  #include "av1/common/reconintra.h"
  #include "av1/common/seg_common.h"
  
  // Returns a context number for the given MB prediction signal
  static InterpFilter get_ref_filter_type(const MODE_INFO *mi,
                                          const MACROBLOCKD *xd, int dir,
                                          MV_REFERENCE_FRAME ref_frame) {
    const MB_MODE_INFO *ref_mbmi = &mi->mbmi;
    (void)xd;
  
    return ((ref_mbmi->ref_frame[0] == ref_frame ||
             ref_mbmi->ref_frame[1] == ref_frame)
                ? av1_extract_interp_filter(ref_mbmi->interp_filters, dir & 0x01)
                : SWITCHABLE_FILTERS);
  }
  
  int av1_get_pred_context_switchable_interp(const MACROBLOCKD *xd, int dir) {
    const MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
    const int ctx_offset =
        (mbmi->ref_frame[1] > INTRA_FRAME) * INTER_FILTER_COMP_OFFSET;
    MV_REFERENCE_FRAME ref_frame =
        (dir < 2) ? mbmi->ref_frame[0] : mbmi->ref_frame[1];
    // Note:
    // The mode info data structure has a one element border above and to the
    // left of the entries corresponding to real macroblocks.
    // The prediction flags in these dummy entries are initialized to 0.
    int filter_type_ctx = ctx_offset + (dir & 0x01) * INTER_FILTER_DIR_OFFSET;
    int left_type = SWITCHABLE_FILTERS;
    int above_type = SWITCHABLE_FILTERS;
  
    if (xd->left_available)
      left_type = get_ref_filter_type(xd->mi[-1], xd, dir, ref_frame);
  
    if (xd->up_available)
      above_type =
          get_ref_filter_type(xd->mi[-xd->mi_stride], xd, dir, ref_frame);
  
    if (left_type == above_type) {
      filter_type_ctx += left_type;
    } else if (left_type == SWITCHABLE_FILTERS) {
      assert(above_type != SWITCHABLE_FILTERS);
      filter_type_ctx += above_type;
    } else if (above_type == SWITCHABLE_FILTERS) {
      assert(left_type != SWITCHABLE_FILTERS);
      filter_type_ctx += left_type;
    } else {
      filter_type_ctx += SWITCHABLE_FILTERS;
    }
  
    return filter_type_ctx;
  }
  
  static void palette_add_to_cache(uint16_t *cache, int *n, uint16_t val) {
    // Do not add an already existing value
    if (*n > 0 && val == cache[*n - 1]) return;
  
    cache[(*n)++] = val;
  }
  
  int av1_get_palette_cache(const MACROBLOCKD *const xd, int plane,
                            uint16_t *cache) {
    const int row = -xd->mb_to_top_edge >> 3;
    // Do not refer to above SB row when on SB boundary.
    const MODE_INFO *const above_mi =
        (row % (1 << MIN_SB_SIZE_LOG2)) ? xd->above_mi : NULL;
    const MODE_INFO *const left_mi = xd->left_mi;
    int above_n = 0, left_n = 0;
    if (above_mi)
      above_n = above_mi->mbmi.palette_mode_info.palette_size[plane != 0];
    if (left_mi)
      left_n = left_mi->mbmi.palette_mode_info.palette_size[plane != 0];
    if (above_n == 0 && left_n == 0) return 0;
    int above_idx = plane * PALETTE_MAX_SIZE;
    int left_idx = plane * PALETTE_MAX_SIZE;
    int n = 0;
    const uint16_t *above_colors =
        above_mi ? above_mi->mbmi.palette_mode_info.palette_colors : NULL;
    const uint16_t *left_colors =
        left_mi ? left_mi->mbmi.palette_mode_info.palette_colors : NULL;
    // Merge the sorted lists of base colors from above and left to get
    // combined sorted color cache.
    while (above_n > 0 && left_n > 0) {
      uint16_t v_above = above_colors[above_idx];
      uint16_t v_left = left_colors[left_idx];
      if (v_left < v_above) {
        palette_add_to_cache(cache, &n, v_left);
        ++left_idx, --left_n;
      } else {
        palette_add_to_cache(cache, &n, v_above);
        ++above_idx, --above_n;
        if (v_left == v_above) ++left_idx, --left_n;
      }
    }
    while (above_n-- > 0) {
      uint16_t val = above_colors[above_idx++];
      palette_add_to_cache(cache, &n, val);
    }
    while (left_n-- > 0) {
      uint16_t val = left_colors[left_idx++];
      palette_add_to_cache(cache, &n, val);
    }
    assert(n <= 2 * PALETTE_MAX_SIZE);
    return n;
  }
  
  // The mode info data structure has a one element border above and to the
  // left of the entries corresponding to real macroblocks.
  // The prediction flags in these dummy entries are initialized to 0.
  // 0 - inter/inter, inter/--, --/inter, --/--
  // 1 - intra/inter, inter/intra
  // 2 - intra/--, --/intra
  // 3 - intra/intra
  int av1_get_intra_inter_context(const MACROBLOCKD *xd) {
    const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
    const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
    const int has_above = xd->up_available;
    const int has_left = xd->left_available;
  
    if (has_above && has_left) {  // both edges available
      const int above_intra = !is_inter_block(above_mbmi);
      const int left_intra = !is_inter_block(left_mbmi);
      return left_intra && above_intra ? 3 : left_intra || above_intra;
    } else if (has_above || has_left) {  // one edge available
      return 2 * !is_inter_block(has_above ? above_mbmi : left_mbmi);
    } else {
      return 0;
    }
  }
  
  #define CHECK_BACKWARD_REFS(ref_frame) \
    (((ref_frame) >= BWDREF_FRAME) && ((ref_frame) <= ALTREF_FRAME))
  #define IS_BACKWARD_REF_FRAME(ref_frame) CHECK_BACKWARD_REFS(ref_frame)
  
  #define CHECK_GOLDEN_OR_LAST3(ref_frame) \
    (((ref_frame) == GOLDEN_FRAME) || ((ref_frame) == LAST3_FRAME))
  
  int av1_get_reference_mode_context(const MACROBLOCKD *xd) {
    int ctx;
    const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
    const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
    const int has_above = xd->up_available;
    const int has_left = xd->left_available;
  
    // Note:
    // The mode info data structure has a one element border above and to the
    // left of the entries corresponding to real macroblocks.
    // The prediction flags in these dummy entries are initialized to 0.
    if (has_above && has_left) {  // both edges available
      if (!has_second_ref(above_mbmi) && !has_second_ref(left_mbmi))
        // neither edge uses comp pred (0/1)
        ctx = IS_BACKWARD_REF_FRAME(above_mbmi->ref_frame[0]) ^
              IS_BACKWARD_REF_FRAME(left_mbmi->ref_frame[0]);
      else if (!has_second_ref(above_mbmi))
        // one of two edges uses comp pred (2/3)
        ctx = 2 + (IS_BACKWARD_REF_FRAME(above_mbmi->ref_frame[0]) ||
                   !is_inter_block(above_mbmi));
      else if (!has_second_ref(left_mbmi))
        // one of two edges uses comp pred (2/3)
        ctx = 2 + (IS_BACKWARD_REF_FRAME(left_mbmi->ref_frame[0]) ||
                   !is_inter_block(left_mbmi));
      else  // both edges use comp pred (4)
        ctx = 4;
    } else if (has_above || has_left) {  // one edge available
      const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
  
      if (!has_second_ref(edge_mbmi))
        // edge does not use comp pred (0/1)
        ctx = IS_BACKWARD_REF_FRAME(edge_mbmi->ref_frame[0]);
      else
        // edge uses comp pred (3)
        ctx = 3;
    } else {  // no edges available (1)
      ctx = 1;
    }
    assert(ctx >= 0 && ctx < COMP_INTER_CONTEXTS);
    return ctx;
  }
  
  int av1_get_comp_reference_type_context(const MACROBLOCKD *xd) {
    int pred_context;
    const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
    const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
    const int above_in_image = xd->up_available;
    const int left_in_image = xd->left_available;
  
    if (above_in_image && left_in_image) {  // both edges available
      const int above_intra = !is_inter_block(above_mbmi);
      const int left_intra = !is_inter_block(left_mbmi);
  
      if (above_intra && left_intra) {  // intra/intra
        pred_context = 2;
      } else if (above_intra || left_intra) {  // intra/inter
        const MB_MODE_INFO *inter_mbmi = above_intra ? left_mbmi : above_mbmi;
  
        if (!has_second_ref(inter_mbmi))  // single pred
          pred_context = 2;
        else  // comp pred
          pred_context = 1 + 2 * has_uni_comp_refs(inter_mbmi);
      } else {  // inter/inter
        const int a_sg = !has_second_ref(above_mbmi);
        const int l_sg = !has_second_ref(left_mbmi);
        const MV_REFERENCE_FRAME frfa = above_mbmi->ref_frame[0];
        const MV_REFERENCE_FRAME frfl = left_mbmi->ref_frame[0];
  
        if (a_sg && l_sg) {  // single/single
          pred_context = 1 + 2 * (!(IS_BACKWARD_REF_FRAME(frfa) ^
                                    IS_BACKWARD_REF_FRAME(frfl)));
        } else if (l_sg || a_sg) {  // single/comp
          const int uni_rfc =
              a_sg ? has_uni_comp_refs(left_mbmi) : has_uni_comp_refs(above_mbmi);
  
          if (!uni_rfc)  // comp bidir
            pred_context = 1;
          else  // comp unidir
            pred_context = 3 + (!(IS_BACKWARD_REF_FRAME(frfa) ^
                                  IS_BACKWARD_REF_FRAME(frfl)));
        } else {  // comp/comp
          const int a_uni_rfc = has_uni_comp_refs(above_mbmi);
          const int l_uni_rfc = has_uni_comp_refs(left_mbmi);
  
          if (!a_uni_rfc && !l_uni_rfc)  // bidir/bidir
            pred_context = 0;
          else if (!a_uni_rfc || !l_uni_rfc)  // unidir/bidir
            pred_context = 2;
          else  // unidir/unidir
            pred_context =
                3 + (!((frfa == BWDREF_FRAME) ^ (frfl == BWDREF_FRAME)));
        }
      }
    } else if (above_in_image || left_in_image) {  // one edge available
      const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;
  
      if (!is_inter_block(edge_mbmi)) {  // intra
        pred_context = 2;
      } else {                           // inter
        if (!has_second_ref(edge_mbmi))  // single pred
          pred_context = 2;
        else  // comp pred
          pred_context = 4 * has_uni_comp_refs(edge_mbmi);
      }
    } else {  // no edges available
      pred_context = 2;
    }
  
    assert(pred_context >= 0 && pred_context < COMP_REF_TYPE_CONTEXTS);
    return pred_context;
  }
  
  // Returns a context number for the given MB prediction signal
  //
  // Signal the uni-directional compound reference frame pair as either
  // (BWDREF, ALTREF), or (LAST, LAST2) / (LAST, LAST3) / (LAST, GOLDEN),
  // conditioning on the pair is known as uni-directional.
  //
  // 3 contexts: Voting is used to compare the count of forward references with
  //             that of backward references from the spatial neighbors.
  int av1_get_pred_context_uni_comp_ref_p(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of forward references (L, L2, L3, or G)
    const int frf_count = ref_counts[LAST_FRAME] + ref_counts[LAST2_FRAME] +
                          ref_counts[LAST3_FRAME] + ref_counts[GOLDEN_FRAME];
    // Count of backward references (B or A)
    const int brf_count = ref_counts[BWDREF_FRAME] + ref_counts[ALTREF2_FRAME] +
                          ref_counts[ALTREF_FRAME];
  
    const int pred_context =
        (frf_count == brf_count) ? 1 : ((frf_count < brf_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < UNI_COMP_REF_CONTEXTS);
    return pred_context;
  }
  
  // Returns a context number for the given MB prediction signal
  //
  // Signal the uni-directional compound reference frame pair as
  // either (LAST, LAST2), or (LAST, LAST3) / (LAST, GOLDEN),
  // conditioning on the pair is known as one of the above three.
  //
  // 3 contexts: Voting is used to compare the count of LAST2_FRAME with the
  //             total count of LAST3/GOLDEN from the spatial neighbors.
  int av1_get_pred_context_uni_comp_ref_p1(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of LAST2
    const int last2_count = ref_counts[LAST2_FRAME];
    // Count of LAST3 or GOLDEN
    const int last3_or_gld_count =
        ref_counts[LAST3_FRAME] + ref_counts[GOLDEN_FRAME];
  
    const int pred_context = (last2_count == last3_or_gld_count)
                                 ? 1
                                 : ((last2_count < last3_or_gld_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < UNI_COMP_REF_CONTEXTS);
    return pred_context;
  }
  
  // Returns a context number for the given MB prediction signal
  //
  // Signal the uni-directional compound reference frame pair as
  // either (LAST, LAST3) or (LAST, GOLDEN),
  // conditioning on the pair is known as one of the above two.
  //
  // 3 contexts: Voting is used to compare the count of LAST3_FRAME with the
  //             total count of GOLDEN_FRAME from the spatial neighbors.
  int av1_get_pred_context_uni_comp_ref_p2(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of LAST3
    const int last3_count = ref_counts[LAST3_FRAME];
    // Count of GOLDEN
    const int gld_count = ref_counts[GOLDEN_FRAME];
  
    const int pred_context =
        (last3_count == gld_count) ? 1 : ((last3_count < gld_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < UNI_COMP_REF_CONTEXTS);
    return pred_context;
  }
  
  // == Common context functions for both comp and single ref ==
  //
  // Obtain contexts to signal a reference frame to be either LAST/LAST2 or
  // LAST3/GOLDEN.
  static int get_pred_context_ll2_or_l3gld(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of LAST + LAST2
    const int last_last2_count = ref_counts[LAST_FRAME] + ref_counts[LAST2_FRAME];
    // Count of LAST3 + GOLDEN
    const int last3_gld_count =
        ref_counts[LAST3_FRAME] + ref_counts[GOLDEN_FRAME];
  
    const int pred_context = (last_last2_count == last3_gld_count)
                                 ? 1
                                 : ((last_last2_count < last3_gld_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
    return pred_context;
  }
  
  // Obtain contexts to signal a reference frame to be either LAST or LAST2.
  static int get_pred_context_last_or_last2(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of LAST
    const int last_count = ref_counts[LAST_FRAME];
    // Count of LAST2
    const int last2_count = ref_counts[LAST2_FRAME];
  
    const int pred_context =
        (last_count == last2_count) ? 1 : ((last_count < last2_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
    return pred_context;
  }
  
  // Obtain contexts to signal a reference frame to be either LAST3 or GOLDEN.
  static int get_pred_context_last3_or_gld(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of LAST3
    const int last3_count = ref_counts[LAST3_FRAME];
    // Count of GOLDEN
    const int gld_count = ref_counts[GOLDEN_FRAME];
  
    const int pred_context =
        (last3_count == gld_count) ? 1 : ((last3_count < gld_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
    return pred_context;
  }
  
  // Obtain contexts to signal a reference frame be either BWDREF/ALTREF2, or
  // ALTREF.
  static int get_pred_context_brfarf2_or_arf(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Counts of BWDREF, ALTREF2, or ALTREF frames (B, A2, or A)
    const int brfarf2_count =
        ref_counts[BWDREF_FRAME] + ref_counts[ALTREF2_FRAME];
    const int arf_count = ref_counts[ALTREF_FRAME];
  
    const int pred_context =
        (brfarf2_count == arf_count) ? 1 : ((brfarf2_count < arf_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
    return pred_context;
  }
  
  // Obtain contexts to signal a reference frame be either BWDREF or ALTREF2.
  static int get_pred_context_brf_or_arf2(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of BWDREF frames (B)
    const int brf_count = ref_counts[BWDREF_FRAME];
    // Count of ALTREF2 frames (A2)
    const int arf2_count = ref_counts[ALTREF2_FRAME];
  
    const int pred_context =
        (brf_count == arf2_count) ? 1 : ((brf_count < arf2_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
    return pred_context;
  }
  
  // == Context functions for comp ref ==
  //
  // Returns a context number for the given MB prediction signal
  // Signal the first reference frame for a compound mode be either
  // GOLDEN/LAST3, or LAST/LAST2.
  int av1_get_pred_context_comp_ref_p(const MACROBLOCKD *xd) {
    return get_pred_context_ll2_or_l3gld(xd);
  }
  
  // Returns a context number for the given MB prediction signal
  // Signal the first reference frame for a compound mode be LAST,
  // conditioning on that it is known either LAST/LAST2.
  int av1_get_pred_context_comp_ref_p1(const MACROBLOCKD *xd) {
    return get_pred_context_last_or_last2(xd);
  }
  
  // Returns a context number for the given MB prediction signal
  // Signal the first reference frame for a compound mode be GOLDEN,
  // conditioning on that it is known either GOLDEN or LAST3.
  int av1_get_pred_context_comp_ref_p2(const MACROBLOCKD *xd) {
    return get_pred_context_last3_or_gld(xd);
  }
  
  // Signal the 2nd reference frame for a compound mode be either
  // ALTREF, or ALTREF2/BWDREF.
  int av1_get_pred_context_comp_bwdref_p(const MACROBLOCKD *xd) {
    return get_pred_context_brfarf2_or_arf(xd);
  }
  
  // Signal the 2nd reference frame for a compound mode be either
  // ALTREF2 or BWDREF.
  int av1_get_pred_context_comp_bwdref_p1(const MACROBLOCKD *xd) {
    return get_pred_context_brf_or_arf2(xd);
  }
  
  // == Context functions for single ref ==
  //
  // For the bit to signal whether the single reference is a forward reference
  // frame or a backward reference frame.
  int av1_get_pred_context_single_ref_p1(const MACROBLOCKD *xd) {
    const uint8_t *const ref_counts = &xd->neighbors_ref_counts[0];
  
    // Count of forward reference frames
    const int fwd_count = ref_counts[LAST_FRAME] + ref_counts[LAST2_FRAME] +
                          ref_counts[LAST3_FRAME] + ref_counts[GOLDEN_FRAME];
    // Count of backward reference frames
    const int bwd_count = ref_counts[BWDREF_FRAME] + ref_counts[ALTREF2_FRAME] +
                          ref_counts[ALTREF_FRAME];
  
    const int pred_context =
        (fwd_count == bwd_count) ? 1 : ((fwd_count < bwd_count) ? 0 : 2);
  
    assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
    return pred_context;
  }
  
  // For the bit to signal whether the single reference is ALTREF_FRAME or
  // non-ALTREF backward reference frame, knowing that it shall be either of
  // these 2 choices.
  int av1_get_pred_context_single_ref_p2(const MACROBLOCKD *xd) {
    return get_pred_context_brfarf2_or_arf(xd);
  }
  
  // For the bit to signal whether the single reference is LAST3/GOLDEN or
  // LAST2/LAST, knowing that it shall be either of these 2 choices.
  int av1_get_pred_context_single_ref_p3(const MACROBLOCKD *xd) {
    return get_pred_context_ll2_or_l3gld(xd);
  }
  
  // For the bit to signal whether the single reference is LAST2_FRAME or
  // LAST_FRAME, knowing that it shall be either of these 2 choices.
  int av1_get_pred_context_single_ref_p4(const MACROBLOCKD *xd) {
    return get_pred_context_last_or_last2(xd);
  }
  
  // For the bit to signal whether the single reference is GOLDEN_FRAME or
  // LAST3_FRAME, knowing that it shall be either of these 2 choices.
  int av1_get_pred_context_single_ref_p5(const MACROBLOCKD *xd) {
    return get_pred_context_last3_or_gld(xd);
  }
  
  // For the bit to signal whether the single reference is ALTREF2_FRAME or
  // BWDREF_FRAME, knowing that it shall be either of these 2 choices.
  int av1_get_pred_context_single_ref_p6(const MACROBLOCKD *xd) {
    return get_pred_context_brf_or_arf2(xd);
  }
  