/*
  * Copyright (c) 2012 Andrew D'Addesio
  * Copyright (c) 2013-2014 Mozilla Corporation

  * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>

  *
  * 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_OPUS_RC_H
 #define AVCODEC_OPUS_RC_H
 
 #include <stdint.h>
 #include "get_bits.h"
 

 #define OPUS_MAX_PACKET_SIZE 1275
 

 #define opus_ilog(i) (av_log2(i) + !!(i))
 
 typedef struct RawBitsContext {
     const uint8_t *position;
     uint32_t bytes;
     uint32_t cachelen;
     uint32_t cacheval;
 } RawBitsContext;
 
 typedef struct OpusRangeCoder {
     GetBitContext gb;
     RawBitsContext rb;
     uint32_t range;
     uint32_t value;

     uint32_t total_bits;

 
     /* Encoder */
     uint8_t buf[OPUS_MAX_PACKET_SIZE + 12]; /* memcpy vs (memmove + overreading) */
     uint8_t *rng_cur;                      /* Current range coded byte */
     int ext;                               /* Awaiting propagation */
     int rem;                               /* Carryout flag */
 
     /* Encoding stats */
     int waste;

 } OpusRangeCoder;
 
 /**
  * CELT: estimate bits of entropy that have thus far been consumed for the
  *       current CELT frame, to integer and fractional (1/8th bit) precision
  */
 static av_always_inline uint32_t opus_rc_tell(const OpusRangeCoder *rc)
 {

     return rc->total_bits - av_log2(rc->range) - 1;

 }
 
 static av_always_inline uint32_t opus_rc_tell_frac(const OpusRangeCoder *rc)
 {
     uint32_t i, total_bits, rcbuffer, range;
 

     total_bits = rc->total_bits << 3;

     rcbuffer   = av_log2(rc->range) + 1;
     range      = rc->range >> (rcbuffer-16);
 
     for (i = 0; i < 3; i++) {
         int bit;
         range = range * range >> 15;
         bit = range >> 16;
         rcbuffer = rcbuffer << 1 | bit;
         range >>= bit;
     }
 
     return total_bits - rcbuffer;
 }
 
 uint32_t ff_opus_rc_dec_cdf(OpusRangeCoder *rc, const uint16_t *cdf);

 void     ff_opus_rc_enc_cdf(OpusRangeCoder *rc, int val, const uint16_t *cdf);
 

 uint32_t ff_opus_rc_dec_log(OpusRangeCoder *rc, uint32_t bits);

 void     ff_opus_rc_enc_log(OpusRangeCoder *rc, int val, uint32_t bits);
 

 uint32_t ff_opus_rc_dec_uint_step(OpusRangeCoder *rc, int k0);

 void     ff_opus_rc_enc_uint_step(OpusRangeCoder *rc, uint32_t val, int k0);
 

 uint32_t ff_opus_rc_dec_uint_tri(OpusRangeCoder *rc, int qn);

 void     ff_opus_rc_enc_uint_tri(OpusRangeCoder *rc, uint32_t k, int qn);
 
 uint32_t ff_opus_rc_dec_uint(OpusRangeCoder *rc, uint32_t size);
 void     ff_opus_rc_enc_uint(OpusRangeCoder *rc, uint32_t val, uint32_t size);
 

 uint32_t ff_opus_rc_get_raw(OpusRangeCoder *rc, uint32_t count);

 void     ff_opus_rc_put_raw(OpusRangeCoder *rc, uint32_t val, uint32_t count);
 

 int      ff_opus_rc_dec_laplace(OpusRangeCoder *rc, uint32_t symbol, int decay);

 void     ff_opus_rc_enc_laplace(OpusRangeCoder *rc, int *value, uint32_t symbol, int decay);
 
 int      ff_opus_rc_dec_init(OpusRangeCoder *rc, const uint8_t *data, int size);
 void     ff_opus_rc_dec_raw_init(OpusRangeCoder *rc, const uint8_t *rightend, uint32_t bytes);

 void     ff_opus_rc_enc_end(OpusRangeCoder *rc, uint8_t *dst, int size);
 void     ff_opus_rc_enc_init(OpusRangeCoder *rc);

 #define OPUS_RC_CHECKPOINT_UPDATE(rc) \
     rc_rollback_bits = opus_rc_tell_frac(rc); \
     rc_rollback_ctx  = *rc
 
 #define OPUS_RC_CHECKPOINT_SPAWN(rc) \
     uint32_t rc_rollback_bits = opus_rc_tell_frac(rc); \
     OpusRangeCoder rc_rollback_ctx = *rc \
 
 #define OPUS_RC_CHECKPOINT_BITS(rc) \
     (opus_rc_tell_frac(rc) - rc_rollback_bits)
 
 #define OPUS_RC_CHECKPOINT_ROLLBACK(rc) \
     memcpy(rc, &rc_rollback_ctx, sizeof(OpusRangeCoder)); \
 

 #endif /* AVCODEC_OPUS_RC_H */