text: /**
   * @file
   * VP5 and VP6 compatible video decoder (common features)
   *
   * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #ifndef AVCODEC_VP56_H
  #define AVCODEC_VP56_H
  
  #include "vp56data.h"
  #include "dsputil.h"
  #include "get_bits.h"
  #include "bytestream.h"
  #include "cabac.h"
  #include "vp56dsp.h"
  
  typedef struct vp56_context VP56Context;
  
  typedef struct {
      int16_t x;
      int16_t y;
  } DECLARE_ALIGNED(4, , VP56mv);
  
  typedef void (*VP56ParseVectorAdjustment)(VP56Context *s,
                                            VP56mv *vect);
  typedef void (*VP56Filter)(VP56Context *s, uint8_t *dst, uint8_t *src,
                             int offset1, int offset2, int stride,
                             VP56mv mv, int mask, int select, int luma);
  typedef void (*VP56ParseCoeff)(VP56Context *s);
  typedef void (*VP56DefaultModelsInit)(VP56Context *s);
  typedef void (*VP56ParseVectorModels)(VP56Context *s);
  typedef void (*VP56ParseCoeffModels)(VP56Context *s);
  typedef int  (*VP56ParseHeader)(VP56Context *s, const uint8_t *buf,
                                  int buf_size, int *golden_frame);
  
  typedef struct {
      int high;
      int bits; /* stored negated (i.e. negative "bits" is a positive number of
                   bits left) in order to eliminate a negate in cache refilling */
      const uint8_t *buffer;
      const uint8_t *end;
      unsigned int code_word;
  } VP56RangeCoder;
  
  typedef struct {
      uint8_t not_null_dc;
      VP56Frame ref_frame;
      DCTELEM dc_coeff;
  } VP56RefDc;
  
  typedef struct {
      uint8_t type;
      VP56mv mv;
  } VP56Macroblock;
  
  typedef struct {
      uint8_t coeff_reorder[64];       /* used in vp6 only */
      uint8_t coeff_index_to_pos[64];  /* used in vp6 only */
      uint8_t vector_sig[2];           /* delta sign */
      uint8_t vector_dct[2];           /* delta coding types */
      uint8_t vector_pdi[2][2];        /* predefined delta init */
      uint8_t vector_pdv[2][7];        /* predefined delta values */
      uint8_t vector_fdv[2][8];        /* 8 bit delta value definition */
      uint8_t coeff_dccv[2][11];       /* DC coeff value */
      uint8_t coeff_ract[2][3][6][11]; /* Run/AC coding type and AC coeff value */
      uint8_t coeff_acct[2][3][3][6][5];/* vp5 only AC coding type for coding group < 3 */
      uint8_t coeff_dcct[2][36][5];    /* DC coeff coding type */
      uint8_t coeff_runv[2][14];       /* run value (vp6 only) */
      uint8_t mb_type[3][10][10];      /* model for decoding MB type */
      uint8_t mb_types_stats[3][10][2];/* contextual, next MB type stats */
  } VP56Model;
  
  struct vp56_context {
      AVCodecContext *avctx;
      DSPContext dsp;
      VP56DSPContext vp56dsp;
      ScanTable scantable;
      AVFrame frames[4];
      AVFrame *framep[6];
      uint8_t *edge_emu_buffer_alloc;
      uint8_t *edge_emu_buffer;
      VP56RangeCoder c;
      VP56RangeCoder cc;
      VP56RangeCoder *ccp;
      int sub_version;
  
      /* frame info */
      int plane_width[4];
      int plane_height[4];
      int mb_width;   /* number of horizontal MB */
      int mb_height;  /* number of vertical MB */
      int block_offset[6];
  
      int quantizer;
      uint16_t dequant_dc;
      uint16_t dequant_ac;
      int8_t *qscale_table;
  
      /* DC predictors management */
      VP56RefDc *above_blocks;
      VP56RefDc left_block[4];
      int above_block_idx[6];
      DCTELEM prev_dc[3][3];    /* [plan][ref_frame] */
  
      /* blocks / macroblock */
      VP56mb mb_type;
      VP56Macroblock *macroblocks;
      DECLARE_ALIGNED(16, DCTELEM, block_coeff)[6][64];
  
      /* motion vectors */
      VP56mv mv[6];  /* vectors for each block in MB */
      VP56mv vector_candidate[2];
      int vector_candidate_pos;
  
      /* filtering hints */
      int filter_header;               /* used in vp6 only */
      int deblock_filtering;
      int filter_selection;
      int filter_mode;
      int max_vector_length;
      int sample_variance_threshold;
  
      uint8_t coeff_ctx[4][64];              /* used in vp5 only */
      uint8_t coeff_ctx_last[4];             /* used in vp5 only */
  
      int has_alpha;
  
      /* upside-down flipping hints */
      int flip;  /* are we flipping ? */
      int frbi;  /* first row block index in MB */
      int srbi;  /* second row block index in MB */
      int stride[4];  /* stride for each plan */
  
      const uint8_t *vp56_coord_div;
      VP56ParseVectorAdjustment parse_vector_adjustment;
      VP56Filter filter;
      VP56ParseCoeff parse_coeff;
      VP56DefaultModelsInit default_models_init;
      VP56ParseVectorModels parse_vector_models;
      VP56ParseCoeffModels parse_coeff_models;
      VP56ParseHeader parse_header;
  
      VP56Model *modelp;
      VP56Model models[2];
  
      /* huffman decoding */
      int use_huffman;
      GetBitContext gb;
      VLC dccv_vlc[2];
      VLC runv_vlc[2];
      VLC ract_vlc[2][3][6];
      unsigned int nb_null[2][2];       /* number of consecutive NULL DC/AC */
  };
  
  
  void ff_vp56_init(AVCodecContext *avctx, int flip, int has_alpha);
  int ff_vp56_free(AVCodecContext *avctx);
  void ff_vp56_init_dequant(VP56Context *s, int quantizer);
  int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
                           AVPacket *avpkt);
  
  
  /**
   * vp56 specific range coder implementation
   */
  
  extern const uint8_t ff_vp56_norm_shift[256];
  void ff_vp56_init_range_decoder(VP56RangeCoder *c, const uint8_t *buf, int buf_size);
  
  static av_always_inline unsigned int vp56_rac_renorm(VP56RangeCoder *c)
  {
      int shift = ff_vp56_norm_shift[c->high];
      int bits = c->bits;
      unsigned int code_word = c->code_word;
  
      c->high   <<= shift;
      code_word <<= shift;
      bits       += shift;
      if(bits >= 0 && c->buffer < c->end) {
          code_word |= bytestream_get_be16(&c->buffer) << bits;
          bits -= 16;
      }
      c->bits = bits;
      return code_word;
  }
  
  #if   ARCH_ARM
  #include "arm/vp56_arith.h"
  #elif ARCH_X86
  #include "x86/vp56_arith.h"
  #endif
  
  #ifndef vp56_rac_get_prob
  #define vp56_rac_get_prob vp56_rac_get_prob
  static av_always_inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob)
  {
      unsigned int code_word = vp56_rac_renorm(c);
      unsigned int low = 1 + (((c->high - 1) * prob) >> 8);
      unsigned int low_shift = low << 16;
      int bit = code_word >= low_shift;
  
      c->high = bit ? c->high - low : low;
      c->code_word = bit ? code_word - low_shift : code_word;
  
      return bit;
  }
  #endif
  
  #ifndef vp56_rac_get_prob_branchy
  // branchy variant, to be used where there's a branch based on the bit decoded
  static av_always_inline int vp56_rac_get_prob_branchy(VP56RangeCoder *c, int prob)
  {
      unsigned long code_word = vp56_rac_renorm(c);
      unsigned low = 1 + (((c->high - 1) * prob) >> 8);
      unsigned low_shift = low << 16;
  
      if (code_word >= low_shift) {
          c->high     -= low;
          c->code_word = code_word - low_shift;
          return 1;
      }
  
      c->high = low;
      c->code_word = code_word;
      return 0;
  }
  #endif
  
  static av_always_inline int vp56_rac_get(VP56RangeCoder *c)
  {
      unsigned int code_word = vp56_rac_renorm(c);
      /* equiprobable */
      int low = (c->high + 1) >> 1;
      unsigned int low_shift = low << 16;
      int bit = code_word >= low_shift;
      if (bit) {
          c->high   -= low;
          code_word -= low_shift;
      } else {
          c->high = low;
      }
  
      c->code_word = code_word;
      return bit;
  }
  
  // rounding is different than vp56_rac_get, is vp56_rac_get wrong?
  static av_always_inline int vp8_rac_get(VP56RangeCoder *c)
  {
      return vp56_rac_get_prob(c, 128);
  }
  
  static av_unused int vp56_rac_gets(VP56RangeCoder *c, int bits)
  {
      int value = 0;
  
      while (bits--) {
          value = (value << 1) | vp56_rac_get(c);
      }
  
      return value;
  }
  
  static av_unused int vp8_rac_get_uint(VP56RangeCoder *c, int bits)
  {
      int value = 0;
  
      while (bits--) {
          value = (value << 1) | vp8_rac_get(c);
      }
  
      return value;
  }
  
  // fixme: add 1 bit to all the calls to this?
  static av_unused int vp8_rac_get_sint(VP56RangeCoder *c, int bits)
  {
      int v;
  
      if (!vp8_rac_get(c))
          return 0;
  
      v = vp8_rac_get_uint(c, bits);
  
      if (vp8_rac_get(c))
          v = -v;
  
      return v;
  }
  
  // P(7)
  static av_unused int vp56_rac_gets_nn(VP56RangeCoder *c, int bits)
  {
      int v = vp56_rac_gets(c, 7) << 1;
      return v + !v;
  }
  
  static av_unused int vp8_rac_get_nn(VP56RangeCoder *c)
  {
      int v = vp8_rac_get_uint(c, 7) << 1;
      return v + !v;
  }
  
  static av_always_inline
  int vp56_rac_get_tree(VP56RangeCoder *c,
                        const VP56Tree *tree,
                        const uint8_t *probs)
  {
      while (tree->val > 0) {
          if (vp56_rac_get_prob(c, probs[tree->prob_idx]))
              tree += tree->val;
          else
              tree++;
      }
      return -tree->val;
  }
  
  /**
   * This is identical to vp8_rac_get_tree except for the possibility of starting
   * on a node other than the root node, needed for coeff decode where this is
   * used to save a bit after a 0 token (by disallowing EOB to immediately follow.)
   */
  static av_always_inline
  int vp8_rac_get_tree_with_offset(VP56RangeCoder *c, const int8_t (*tree)[2],
                                   const uint8_t *probs, int i)
  {
      do {
          i = tree[i][vp56_rac_get_prob(c, probs[i])];
      } while (i > 0);
  
      return -i;
  }
  
  // how probabilities are associated with decisions is different I think
  // well, the new scheme fits in the old but this way has one fewer branches per decision
  static av_always_inline
  int vp8_rac_get_tree(VP56RangeCoder *c, const int8_t (*tree)[2],
                       const uint8_t *probs)
  {
      return vp8_rac_get_tree_with_offset(c, tree, probs, 0);
  }
  
  // DCTextra
  static av_always_inline int vp8_rac_get_coeff(VP56RangeCoder *c, const uint8_t *prob)
  {
      int v = 0;
  
      do {
          v = (v<<1) + vp56_rac_get_prob(c, *prob++);
      } while (*prob);
  
      return v;
  }
  
  #endif /* AVCODEC_VP56_H */
  