/*
  * AC-3 DSP utils
  * Copyright (c) 2011 Justin Ruggles
  *
  * 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
  */
 

 #include "libavutil/avassert.h"

 #include "avcodec.h"

 #include "ac3.h"

 #include "ac3dsp.h"
 
 static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
 {
     int blk, i;
 
     if (!num_reuse_blocks)
         return;
 
     for (i = 0; i < nb_coefs; i++) {
         uint8_t min_exp = *exp;
         uint8_t *exp1 = exp + 256;
         for (blk = 0; blk < num_reuse_blocks; blk++) {
             uint8_t next_exp = *exp1;
             if (next_exp < min_exp)
                 min_exp = next_exp;
             exp1 += 256;
         }
         *exp++ = min_exp;
     }
 }
 

 static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
 {
     int i, v = 0;
     for (i = 0; i < len; i++)
         v |= abs(src[i]);
     return v;
 }
 

 static void ac3_lshift_int16_c(int16_t *src, unsigned int len,
                                unsigned int shift)
 {
     uint32_t *src32 = (uint32_t *)src;
     const uint32_t mask = ~(((1 << shift) - 1) << 16);
     int i;
     len >>= 1;
     for (i = 0; i < len; i += 8) {
         src32[i  ] = (src32[i  ] << shift) & mask;
         src32[i+1] = (src32[i+1] << shift) & mask;
         src32[i+2] = (src32[i+2] << shift) & mask;
         src32[i+3] = (src32[i+3] << shift) & mask;
         src32[i+4] = (src32[i+4] << shift) & mask;
         src32[i+5] = (src32[i+5] << shift) & mask;
         src32[i+6] = (src32[i+6] << shift) & mask;
         src32[i+7] = (src32[i+7] << shift) & mask;
     }
 }
 
 static void ac3_rshift_int32_c(int32_t *src, unsigned int len,
                                unsigned int shift)
 {
     do {
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         len -= 8;
     } while (len > 0);
 }
 

 static void float_to_fixed24_c(int32_t *dst, const float *src, unsigned int len)
 {
     const float scale = 1 << 24;
     do {
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         len -= 8;
     } while (len > 0);
 }
 

 static void ac3_bit_alloc_calc_bap_c(int16_t *mask, int16_t *psd,
                                      int start, int end,
                                      int snr_offset, int floor,
                                      const uint8_t *bap_tab, uint8_t *bap)
 {
     int bin, band;
 
     /* special case, if snr offset is -960, set all bap's to zero */
     if (snr_offset == -960) {
         memset(bap, 0, AC3_MAX_COEFS);
         return;
     }
 
     bin  = start;
     band = ff_ac3_bin_to_band_tab[start];
     do {
         int m = (FFMAX(mask[band] - snr_offset - floor, 0) & 0x1FE0) + floor;
         int band_end = FFMIN(ff_ac3_band_start_tab[band+1], end);
         for (; bin < band_end; bin++) {
             int address = av_clip((psd[bin] - m) >> 5, 0, 63);
             bap[bin] = bap_tab[address];
         }
     } while (end > ff_ac3_band_start_tab[band++]);
 }
 

 static void ac3_update_bap_counts_c(uint16_t mant_cnt[16], uint8_t *bap,
                                     int len)

 {

     while (len-- > 0)

         mant_cnt[bap[len]]++;
 }

 DECLARE_ALIGNED(16, const uint16_t, ff_ac3_bap_bits)[16] = {
     0,  0,  0,  3,  0,  4,  5,  6,  7,  8,  9, 10, 11, 12, 14, 16
 };
 
 static int ac3_compute_mantissa_size_c(uint16_t mant_cnt[6][16])
 {
     int blk, bap;
     int bits = 0;
 
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         // bap=1 : 3 mantissas in 5 bits
         bits += (mant_cnt[blk][1] / 3) * 5;
         // bap=2 : 3 mantissas in 7 bits
         // bap=4 : 2 mantissas in 7 bits
         bits += ((mant_cnt[blk][2] / 3) + (mant_cnt[blk][4] >> 1)) * 7;
         // bap=3 : 1 mantissa in 3 bits
         bits += mant_cnt[blk][3] * 3;
         // bap=5 to 15 : get bits per mantissa from table
         for (bap = 5; bap < 16; bap++)
             bits += mant_cnt[blk][bap] * ff_ac3_bap_bits[bap];

     }
     return bits;
 }
 

 static void ac3_extract_exponents_c(uint8_t *exp, int32_t *coef, int nb_coefs)
 {
     int i;
 
     for (i = 0; i < nb_coefs; i++) {
         int e;
         int v = abs(coef[i]);
         if (v == 0)
             e = 24;
         else {
             e = 23 - av_log2(v);
             if (e >= 24) {
                 e = 24;
                 coef[i] = 0;

             } else if (e < 0) {
                 e = 0;
                 coef[i] = av_clip(coef[i], -16777215, 16777215);

             }
         }
         exp[i] = e;
     }
 }
 

 av_cold void ff_ac3dsp_init(AC3DSPContext *c, int bit_exact)

 {
     c->ac3_exponent_min = ac3_exponent_min_c;

     c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;

     c->ac3_lshift_int16 = ac3_lshift_int16_c;
     c->ac3_rshift_int32 = ac3_rshift_int32_c;

     c->float_to_fixed24 = float_to_fixed24_c;

     c->bit_alloc_calc_bap = ac3_bit_alloc_calc_bap_c;

     c->update_bap_counts = ac3_update_bap_counts_c;

     c->compute_mantissa_size = ac3_compute_mantissa_size_c;

     c->extract_exponents = ac3_extract_exponents_c;

     if (ARCH_ARM)
         ff_ac3dsp_init_arm(c, bit_exact);

     if (HAVE_MMX)

         ff_ac3dsp_init_x86(c, bit_exact);

 }