/*

  * Common code between the AC-3 encoder and decoder

  * Copyright (c) 2000 Fabrice Bellard

  *
  * 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 code between the AC-3 encoder and decoder.

  */
 
 #include "avcodec.h"
 #include "ac3.h"

 #include "get_bits.h"

 /**
  * Starting frequency coefficient bin for each critical band.
  */

 const uint8_t ff_ac3_band_start_tab[AC3_CRITICAL_BANDS+1] = {

       0,  1,   2,   3,   4,   5,   6,   7,   8,   9,
      10,  11, 12,  13,  14,  15,  16,  17,  18,  19,
      20,  21, 22,  23,  24,  25,  26,  27,  28,  31,
      34,  37, 40,  43,  46,  49,  55,  61,  67,  73,
      79,  85, 97, 109, 121, 133, 157, 181, 205, 229, 253
 };
 

 #if CONFIG_HARDCODED_TABLES
 

 /**

  * Map each frequency coefficient bin to the critical band that contains it.

  */

 const uint8_t ff_ac3_bin_to_band_tab[253] = {

      0,
      1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12,
     13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
     25, 26, 27, 28, 28, 28, 29, 29, 29, 30, 30, 30,
     31, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34,
     35, 35, 35, 35, 35, 35, 36, 36, 36, 36, 36, 36,
     37, 37, 37, 37, 37, 37, 38, 38, 38, 38, 38, 38,
     39, 39, 39, 39, 39, 39, 40, 40, 40, 40, 40, 40,
     41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
     42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
     43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43,
     44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44,
     45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45,
     45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45,
     46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
     46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
     47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47,
     47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47,
     48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
     48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
     49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49,
     49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49
 };
 
 #else /* CONFIG_HARDCODED_TABLES */

 uint8_t ff_ac3_bin_to_band_tab[253];

 #endif

 static inline int calc_lowcomp1(int a, int b0, int b1, int c)
 {
     if ((b0 + 256) == b1) {
         a = c;
     } else if (b0 > b1) {
         a = FFMAX(a - 64, 0);
     }
     return a;
 }
 
 static inline int calc_lowcomp(int a, int b0, int b1, int bin)
 {
     if (bin < 7) {
         return calc_lowcomp1(a, b0, b1, 384);
     } else if (bin < 20) {
         return calc_lowcomp1(a, b0, b1, 320);
     } else {
         return FFMAX(a - 128, 0);
     }
 }
 

 void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,

                                int16_t *band_psd)

 {

     int bin, band;

 
     /* exponent mapping to PSD */

     for (bin = start; bin < end; bin++) {

         psd[bin]=(3072 - (exp[bin] << 7));
     }
 
     /* PSD integration */

     bin  = start;

     band = ff_ac3_bin_to_band_tab[start];

     do {

         int v = psd[bin++];

         int band_end = FFMIN(ff_ac3_band_start_tab[band+1], end);

         for (; bin < band_end; bin++) {

             int max = FFMAX(v, psd[bin]);

             /* logadd */

             int adr = FFMIN(max - ((v + psd[bin] + 1) >> 1), 255);
             v = max + ff_ac3_log_add_tab[adr];

         }

         band_psd[band++] = v;

     } while (end > ff_ac3_band_start_tab[band]);

 }
 

 int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,

                                int start, int end, int fast_gain, int is_lfe,
                                int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
                                uint8_t *dba_lengths, uint8_t *dba_values,
                                int16_t *mask)

 {

     int16_t excite[AC3_CRITICAL_BANDS]; /* excitation */

     int band;
     int band_start, band_end, begin, end1;

     int lowcomp, fastleak, slowleak;

 
     /* excitation function */

     band_start = ff_ac3_bin_to_band_tab[start];
     band_end   = ff_ac3_bin_to_band_tab[end-1] + 1;

     if (band_start == 0) {

         lowcomp = 0;

         lowcomp = calc_lowcomp1(lowcomp, band_psd[0], band_psd[1], 384);
         excite[0] = band_psd[0] - fast_gain - lowcomp;
         lowcomp = calc_lowcomp1(lowcomp, band_psd[1], band_psd[2], 384);
         excite[1] = band_psd[1] - fast_gain - lowcomp;

         begin = 7;

         for (band = 2; band < 7; band++) {
             if (!(is_lfe && band == 6))
                 lowcomp = calc_lowcomp1(lowcomp, band_psd[band], band_psd[band+1], 384);
             fastleak = band_psd[band] - fast_gain;
             slowleak = band_psd[band] - s->slow_gain;
             excite[band] = fastleak - lowcomp;
             if (!(is_lfe && band == 6)) {
                 if (band_psd[band] <= band_psd[band+1]) {
                     begin = band + 1;

                     break;
                 }
             }
         }
 

         end1 = FFMIN(band_end, 22);
         for (band = begin; band < end1; band++) {
             if (!(is_lfe && band == 6))
                 lowcomp = calc_lowcomp(lowcomp, band_psd[band], band_psd[band+1], band);
             fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
             slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
             excite[band] = FFMAX(fastleak - lowcomp, slowleak);

         }
         begin = 22;
     } else {
         /* coupling channel */

         begin = band_start;

         fastleak = (s->cpl_fast_leak << 8) + 768;
         slowleak = (s->cpl_slow_leak << 8) + 768;

     }
 

     for (band = begin; band < band_end; band++) {
         fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
         slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
         excite[band] = FFMAX(fastleak, slowleak);

     }
 
     /* compute masking curve */
 

     for (band = band_start; band < band_end; band++) {
         int tmp = s->db_per_bit - band_psd[band];

         if (tmp > 0) {

             excite[band] += tmp >> 2;

         }

         mask[band] = FFMAX(ff_ac3_hearing_threshold_tab[band >> s->sr_shift][s->sr_code], excite[band]);

     }
 
     /* delta bit allocation */
 

     if (dba_mode == DBA_REUSE || dba_mode == DBA_NEW) {

         int i, seg, delta;

         if (dba_nsegs > 8)

             return -1;

         band = band_start;

         for (seg = 0; seg < dba_nsegs; seg++) {
             band += dba_offsets[seg];

             if (band >= AC3_CRITICAL_BANDS || dba_lengths[seg] > AC3_CRITICAL_BANDS-band)

                 return -1;

             if (dba_values[seg] >= 4) {
                 delta = (dba_values[seg] - 3) << 7;

             } else {

                 delta = (dba_values[seg] - 4) << 7;

             }

             for (i = 0; i < dba_lengths[seg]; i++) {
                 mask[band++] += delta;

             }
         }
     }

     return 0;

 }

 /**

  * Initialize some tables.

  * note: This function must remain thread safe because it is called by the
  *       AVParser init code.
  */

 av_cold void ff_ac3_common_init(void)

 {

 #if !CONFIG_HARDCODED_TABLES

     /* compute ff_ac3_bin_to_band_tab from ff_ac3_band_start_tab */

     int bin = 0, band;

     for (band = 0; band < AC3_CRITICAL_BANDS; band++) {

         int band_end = ff_ac3_band_start_tab[band+1];

         while (bin < band_end)

             ff_ac3_bin_to_band_tab[bin++] = band;

     }

 #endif /* !CONFIG_HARDCODED_TABLES */

 }