/*
  * Copyright (c) 2012 Konstantin Shishkov
  *

  * 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
  */
 
 /**
  * @file
  * Common header for Microsoft Screen 1 and 2
  */
 
 #ifndef AVCODEC_MSS12_H
 #define AVCODEC_MSS12_H
 

 #include "libavutil/intreadwrite.h"

 #include "avcodec.h"
 #include "get_bits.h"

 #include "bytestream.h"

 
 #define MODEL_MIN_SYMS    2
 #define MODEL_MAX_SYMS  256
 #define THRESH_ADAPTIVE  -1
 #define THRESH_LOW       15
 #define THRESH_HIGH      50
 
 typedef struct Model {

     int16_t cum_prob[MODEL_MAX_SYMS + 1];
     int16_t weights[MODEL_MAX_SYMS + 1];
     uint8_t idx2sym[MODEL_MAX_SYMS + 1];

     int num_syms;
     int thr_weight, threshold;
 } Model;
 
 typedef struct ArithCoder {
     int low, high, value;

     union {
         GetBitContext *gb;
         GetByteContext *gB;
     } gbc;

     int (*get_model_sym)(struct ArithCoder *c, Model *m);
     int (*get_number)   (struct ArithCoder *c, int n);
 } ArithCoder;
 
 typedef struct PixContext {
     int cache_size, num_syms;
     uint8_t cache[12];
     Model cache_model, full_model;

     Model sec_models[15][4];

     int special_initial_cache;

 } PixContext;
 

 struct MSS12Context;
 
 typedef struct SliceContext {
     struct MSS12Context *c;
     Model      intra_region, inter_region;
     Model      pivot, edge_mode, split_mode;
     PixContext intra_pix_ctx, inter_pix_ctx;
 } SliceContext;
 

 typedef struct MSS12Context {
     AVCodecContext *avctx;
     uint32_t       pal[256];

     uint8_t        *pal_pic;
     uint8_t        *last_pal_pic;

     ptrdiff_t      pal_stride;

     uint8_t        *mask;

     ptrdiff_t      mask_stride;

     uint8_t        *rgb_pic;
     uint8_t        *last_rgb_pic;

     ptrdiff_t      rgb_stride;

     int            free_colours;
     int            keyframe;

     int            mvX, mvY;

     int            corrupted;

     int            slice_split;
     int            full_model_syms;

 } MSS12Context;
 

 int ff_mss12_decode_rect(SliceContext *ctx, ArithCoder *acoder,

                          int x, int y, int width, int height);
 void ff_mss12_model_update(Model *m, int val);

 void ff_mss12_slicecontext_reset(SliceContext *sc);

 int ff_mss12_decode_init(MSS12Context *c, int version,
                          SliceContext *sc1, SliceContext *sc2);
 int ff_mss12_decode_end(MSS12Context *ctx);

 #define ARITH_GET_BIT(prefix)                                           \
 static int prefix ## _get_bit(ArithCoder *c)                            \

 {                                                                       \
     int range = c->high - c->low + 1;                                   \

     int bit   = 2 * c->value - c->low >= c->high;                       \

                                                                         \
     if (bit)                                                            \
         c->low += range >> 1;                                           \
     else                                                                \
         c->high = c->low + (range >> 1) - 1;                            \
                                                                         \

     prefix ## _normalise(c);                                            \

                                                                         \
     return bit;                                                         \
 }
 

 #define ARITH_GET_MODEL_SYM(prefix)                                     \
 static int prefix ## _get_model_sym(ArithCoder *c, Model *m)            \

 {                                                                       \
     int idx, val;                                                       \
                                                                         \

     idx = prefix ## _get_prob(c, m->cum_prob);                          \

                                                                         \
     val = m->idx2sym[idx];                                              \
     ff_mss12_model_update(m, idx);                                      \
                                                                         \

     prefix ## _normalise(c);                                            \

                                                                         \
     return val;                                                         \
 }

 
 #endif /* AVCODEC_MSS12_H */