/*

  * G.722 ADPCM audio encoder/decoder

  *
  * Copyright (c) CMU 1993 Computer Science, Speech Group
  *                        Chengxiang Lu and Alex Hauptmann
  * Copyright (c) 2005 Steve Underwood <steveu at coppice.org>
  * Copyright (c) 2009 Kenan Gillet
  * Copyright (c) 2010 Martin Storsjo
  *
  * 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
  * G.722 ADPCM audio codec
  *
  * This G.722 decoder is a bit-exact implementation of the ITU G.722
  * specification for all three specified bitrates - 64000bps, 56000bps
  * and 48000bps. It passes the ITU tests.
  *
  * @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits
  *       respectively of each byte are ignored.
  */
 
 #include "mathops.h"

 #include "g722.h"

 
 static const int8_t sign_lookup[2] = { -1, 1 };
 
 static const int16_t inv_log2_table[32] = {
     2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383,
     2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834,
     2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371,
     3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008
 };
 static const int16_t high_log_factor_step[2] = { 798, -214 };

 const int16_t ff_g722_high_inv_quant[4] = { -926, -202, 926, 202 };

 /**
  * low_log_factor_step[index] == wl[rl42[index]]
  */
 static const int16_t low_log_factor_step[16] = {
      -60, 3042, 1198, 538, 334, 172,  58, -30,
     3042, 1198,  538, 334, 172,  58, -30, -60
 };

 const int16_t ff_g722_low_inv_quant4[16] = {

        0, -2557, -1612, -1121,  -786,  -530,  -323,  -150,
     2557,  1612,  1121,   786,   530,   323,   150,     0
 };

 const int16_t ff_g722_low_inv_quant6[64] = {

      -17,   -17,   -17,   -17, -3101, -2738, -2376, -2088,
    -1873, -1689, -1535, -1399, -1279, -1170, -1072,  -982,
     -899,  -822,  -750,  -682,  -618,  -558,  -501,  -447,
     -396,  -347,  -300,  -254,  -211,  -170,  -130,   -91,
     3101,  2738,  2376,  2088,  1873,  1689,  1535,  1399,
     1279,  1170,  1072,   982,   899,   822,   750,   682,
      618,   558,   501,   447,   396,   347,   300,   254,
      211,   170,   130,    91,    54,    17,   -54,   -17
 };

 static inline void s_zero(int cur_diff, struct G722Band *band)
 {
     int s_zero = 0;
 
     #define ACCUM(k, x, d) do { \
             int tmp = x; \
             band->zero_mem[k] = ((band->zero_mem[k] * 255) >> 8) + \
                d*((band->diff_mem[k]^cur_diff) < 0 ? -128 : 128); \
             band->diff_mem[k] = tmp; \
             s_zero += (tmp * band->zero_mem[k]) >> 15; \
         } while (0)
     if (cur_diff) {
         ACCUM(5, band->diff_mem[4], 1);
         ACCUM(4, band->diff_mem[3], 1);
         ACCUM(3, band->diff_mem[2], 1);
         ACCUM(2, band->diff_mem[1], 1);
         ACCUM(1, band->diff_mem[0], 1);

         ACCUM(0, cur_diff * 2, 1);

     } else {
         ACCUM(5, band->diff_mem[4], 0);
         ACCUM(4, band->diff_mem[3], 0);
         ACCUM(3, band->diff_mem[2], 0);
         ACCUM(2, band->diff_mem[1], 0);
         ACCUM(1, band->diff_mem[0], 0);

         ACCUM(0, cur_diff * 2, 0);

     }
     #undef ACCUM
     band->s_zero = s_zero;
 }
 

 /**
  * adaptive predictor
  *
  * @param cur_diff the dequantized and scaled delta calculated from the
  *                 current codeword
  */
 static void do_adaptive_prediction(struct G722Band *band, const int cur_diff)
 {

     int sg[2], limit, cur_qtzd_reconst;

 
     const int cur_part_reconst = band->s_zero + cur_diff < 0;
 
     sg[0] = sign_lookup[cur_part_reconst != band->part_reconst_mem[0]];
     sg[1] = sign_lookup[cur_part_reconst == band->part_reconst_mem[1]];
     band->part_reconst_mem[1] = band->part_reconst_mem[0];
     band->part_reconst_mem[0] = cur_part_reconst;
 
     band->pole_mem[1] = av_clip((sg[0] * av_clip(band->pole_mem[0], -8191, 8191) >> 5) +

                                 (sg[1] * 128) + (band->pole_mem[1] * 127 >> 7), -12288, 12288);

 
     limit = 15360 - band->pole_mem[1];
     band->pole_mem[0] = av_clip(-192 * sg[0] + (band->pole_mem[0] * 255 >> 8), -limit, limit);
 

     s_zero(cur_diff, band);

     cur_qtzd_reconst = av_clip_int16((band->s_predictor + cur_diff) * 2);

     band->s_predictor = av_clip_int16(band->s_zero +
                                       (band->pole_mem[0] * cur_qtzd_reconst >> 15) +
                                       (band->pole_mem[1] * band->prev_qtzd_reconst >> 15));
     band->prev_qtzd_reconst = cur_qtzd_reconst;
 }
 

 static inline int linear_scale_factor(const int log_factor)

 {
     const int wd1 = inv_log2_table[(log_factor >> 6) & 31];
     const int shift = log_factor >> 11;
     return shift < 0 ? wd1 >> -shift : wd1 << shift;
 }
 

 void ff_g722_update_low_predictor(struct G722Band *band, const int ilow)

 {
     do_adaptive_prediction(band,

                            band->scale_factor * ff_g722_low_inv_quant4[ilow] >> 10);

 
     // quantizer adaptation
     band->log_factor   = av_clip((band->log_factor * 127 >> 7) +
                                  low_log_factor_step[ilow], 0, 18432);
     band->scale_factor = linear_scale_factor(band->log_factor - (8 << 11));
 }
 

 void ff_g722_update_high_predictor(struct G722Band *band, const int dhigh,

                                   const int ihigh)
 {
     do_adaptive_prediction(band, dhigh);
 
     // quantizer adaptation
     band->log_factor   = av_clip((band->log_factor * 127 >> 7) +
                                  high_log_factor_step[ihigh&1], 0, 22528);
     band->scale_factor = linear_scale_factor(band->log_factor - (10 << 11));
 }