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imdct.c

/* 
 *  imdct.c
 *
 *    Copyright (C) Aaron Holtzman - May 1999
 *
 *  This file is part of ac3dec, a free Dolby AC-3 stream decoder.
 *    
 *  ac3dec is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *   
 *  ac3dec 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 General Public License for more details.
 *   
 *  You should have received a copy of the GNU General Public License
 *  along with GNU Make; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
 *
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "ac3.h"
#include "ac3_internal.h"


#include "decode.h"
#include "imdct.h"

void imdct_do_256(float data[],float delay[]);
void imdct_do_512(float data[],float delay[]);

typedef struct complex_s
{
      float real;
      float imag;
} complex_t;


#define N 512


/* 128 point bit-reverse LUT */
static uint_8 bit_reverse_512[] = {
      0x00, 0x40, 0x20, 0x60, 0x10, 0x50, 0x30, 0x70, 
      0x08, 0x48, 0x28, 0x68, 0x18, 0x58, 0x38, 0x78, 
      0x04, 0x44, 0x24, 0x64, 0x14, 0x54, 0x34, 0x74, 
      0x0c, 0x4c, 0x2c, 0x6c, 0x1c, 0x5c, 0x3c, 0x7c, 
      0x02, 0x42, 0x22, 0x62, 0x12, 0x52, 0x32, 0x72, 
      0x0a, 0x4a, 0x2a, 0x6a, 0x1a, 0x5a, 0x3a, 0x7a, 
      0x06, 0x46, 0x26, 0x66, 0x16, 0x56, 0x36, 0x76, 
      0x0e, 0x4e, 0x2e, 0x6e, 0x1e, 0x5e, 0x3e, 0x7e, 
      0x01, 0x41, 0x21, 0x61, 0x11, 0x51, 0x31, 0x71, 
      0x09, 0x49, 0x29, 0x69, 0x19, 0x59, 0x39, 0x79, 
      0x05, 0x45, 0x25, 0x65, 0x15, 0x55, 0x35, 0x75, 
      0x0d, 0x4d, 0x2d, 0x6d, 0x1d, 0x5d, 0x3d, 0x7d, 
      0x03, 0x43, 0x23, 0x63, 0x13, 0x53, 0x33, 0x73, 
      0x0b, 0x4b, 0x2b, 0x6b, 0x1b, 0x5b, 0x3b, 0x7b, 
      0x07, 0x47, 0x27, 0x67, 0x17, 0x57, 0x37, 0x77, 
      0x0f, 0x4f, 0x2f, 0x6f, 0x1f, 0x5f, 0x3f, 0x7f};

static uint_8 bit_reverse_256[] = {
      0x00, 0x20, 0x10, 0x30, 0x08, 0x28, 0x18, 0x38, 
      0x04, 0x24, 0x14, 0x34, 0x0c, 0x2c, 0x1c, 0x3c, 
      0x02, 0x22, 0x12, 0x32, 0x0a, 0x2a, 0x1a, 0x3a, 
      0x06, 0x26, 0x16, 0x36, 0x0e, 0x2e, 0x1e, 0x3e, 
      0x01, 0x21, 0x11, 0x31, 0x09, 0x29, 0x19, 0x39, 
      0x05, 0x25, 0x15, 0x35, 0x0d, 0x2d, 0x1d, 0x3d, 
      0x03, 0x23, 0x13, 0x33, 0x0b, 0x2b, 0x1b, 0x3b, 
      0x07, 0x27, 0x17, 0x37, 0x0f, 0x2f, 0x1f, 0x3f};

static complex_t buf[128];

/* Twiddle factor LUT */
static complex_t *w[7];
static complex_t w_1[1];
static complex_t w_2[2];
static complex_t w_4[4];
static complex_t w_8[8];
static complex_t w_16[16];
static complex_t w_32[32];
static complex_t w_64[64];

/* Twiddle factors for IMDCT */
static float xcos1[128];
static float xsin1[128];
static float xcos2[64];
static float xsin2[64];

/* Delay buffer for time domain interleaving */
static float delay[6][256];

/* Windowing function for Modified DCT - Thank you acroread */
static float window[] = {
      0.00014, 0.00024, 0.00037, 0.00051, 0.00067, 0.00086, 0.00107, 0.00130,
      0.00157, 0.00187, 0.00220, 0.00256, 0.00297, 0.00341, 0.00390, 0.00443,
      0.00501, 0.00564, 0.00632, 0.00706, 0.00785, 0.00871, 0.00962, 0.01061,
      0.01166, 0.01279, 0.01399, 0.01526, 0.01662, 0.01806, 0.01959, 0.02121,
      0.02292, 0.02472, 0.02662, 0.02863, 0.03073, 0.03294, 0.03527, 0.03770,
      0.04025, 0.04292, 0.04571, 0.04862, 0.05165, 0.05481, 0.05810, 0.06153,
      0.06508, 0.06878, 0.07261, 0.07658, 0.08069, 0.08495, 0.08935, 0.09389,
      0.09859, 0.10343, 0.10842, 0.11356, 0.11885, 0.12429, 0.12988, 0.13563,
      0.14152, 0.14757, 0.15376, 0.16011, 0.16661, 0.17325, 0.18005, 0.18699,
      0.19407, 0.20130, 0.20867, 0.21618, 0.22382, 0.23161, 0.23952, 0.24757,
      0.25574, 0.26404, 0.27246, 0.28100, 0.28965, 0.29841, 0.30729, 0.31626,
      0.32533, 0.33450, 0.34376, 0.35311, 0.36253, 0.37204, 0.38161, 0.39126,
      0.40096, 0.41072, 0.42054, 0.43040, 0.44030, 0.45023, 0.46020, 0.47019,
      0.48020, 0.49022, 0.50025, 0.51028, 0.52031, 0.53033, 0.54033, 0.55031,
      0.56026, 0.57019, 0.58007, 0.58991, 0.59970, 0.60944, 0.61912, 0.62873,
      0.63827, 0.64774, 0.65713, 0.66643, 0.67564, 0.68476, 0.69377, 0.70269,
      0.71150, 0.72019, 0.72877, 0.73723, 0.74557, 0.75378, 0.76186, 0.76981,
      0.77762, 0.78530, 0.79283, 0.80022, 0.80747, 0.81457, 0.82151, 0.82831,
      0.83496, 0.84145, 0.84779, 0.85398, 0.86001, 0.86588, 0.87160, 0.87716,
      0.88257, 0.88782, 0.89291, 0.89785, 0.90264, 0.90728, 0.91176, 0.91610,
      0.92028, 0.92432, 0.92822, 0.93197, 0.93558, 0.93906, 0.94240, 0.94560,
      0.94867, 0.95162, 0.95444, 0.95713, 0.95971, 0.96217, 0.96451, 0.96674,
      0.96887, 0.97089, 0.97281, 0.97463, 0.97635, 0.97799, 0.97953, 0.98099,
      0.98236, 0.98366, 0.98488, 0.98602, 0.98710, 0.98811, 0.98905, 0.98994,
      0.99076, 0.99153, 0.99225, 0.99291, 0.99353, 0.99411, 0.99464, 0.99513,
      0.99558, 0.99600, 0.99639, 0.99674, 0.99706, 0.99736, 0.99763, 0.99788,
      0.99811, 0.99831, 0.99850, 0.99867, 0.99882, 0.99895, 0.99908, 0.99919,
      0.99929, 0.99938, 0.99946, 0.99953, 0.99959, 0.99965, 0.99969, 0.99974,
      0.99978, 0.99981, 0.99984, 0.99986, 0.99988, 0.99990, 0.99992, 0.99993,
      0.99994, 0.99995, 0.99996, 0.99997, 0.99998, 0.99998, 0.99998, 0.99999,
      0.99999, 0.99999, 0.99999, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000,
      1.00000, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000, 1.00000 };


static inline void swap_cmplx(complex_t *a, complex_t *b)
{
      complex_t tmp;

      tmp = *a;
      *a = *b;
      *b = tmp;
}



static inline complex_t cmplx_mult(complex_t a, complex_t b)
{
      complex_t ret;

      ret.real = a.real * b.real - a.imag * b.imag;
      ret.imag = a.real * b.imag + a.imag * b.real;

      return ret;
}

void imdct_init(void)
{
      int i,k;
      complex_t angle_step;
      complex_t current_angle;

      /* Twiddle factors to turn IFFT into IMDCT */
      for( i=0; i < 128; i++)
      {
            xcos1[i] = -cos(2.0f * M_PI * (8*i+1)/(8*N)) ; 
            xsin1[i] = -sin(2.0f * M_PI * (8*i+1)/(8*N)) ;
      }
      
      /* More twiddle factors to turn IFFT into IMDCT */
      for( i=0; i < 64; i++)
      {
            xcos2[i] = -cos(2.0f * M_PI * (8*i+1)/(4*N)) ; 
            xsin2[i] = -sin(2.0f * M_PI * (8*i+1)/(4*N)) ;
      }

      /* Canonical twiddle factors for FFT */
      w[0] = w_1;
      w[1] = w_2;
      w[2] = w_4;
      w[3] = w_8;
      w[4] = w_16;
      w[5] = w_32;
      w[6] = w_64;

      for( i = 0; i < 7; i++)
      {
            angle_step.real = cos(-2.0 * M_PI / (1 << (i+1)));
            angle_step.imag = sin(-2.0 * M_PI / (1 << (i+1)));

            current_angle.real = 1.0;
            current_angle.imag = 0.0;

            for (k = 0; k < 1 << i; k++)
            {
                  w[i][k] = current_angle;
                  current_angle = cmplx_mult(current_angle,angle_step);
            }
      }
}

void
imdct_do_512(float data[],float delay[])
{
      int i,k;
      int p,q;
      int m;
      int two_m;
      int two_m_plus_one;

      float tmp_a_i;
      float tmp_a_r;
      float tmp_b_i;
      float tmp_b_r;

      float *data_ptr;
      float *delay_ptr;
      float *window_ptr;
      
      //
      // 512 IMDCT with source and dest data in 'data'
      //
      
      // Pre IFFT complex multiply plus IFFT cmplx conjugate 
      for( i=0; i < 128; i++)
      {
            /* z[i] = (X[256-2*i-1] + j * X[2*i]) * (xcos1[i] + j * xsin1[i]) ; */ 
            buf[i].real =         (data[256-2*i-1] * xcos1[i])  -  (data[2*i]       * xsin1[i]);
        buf[i].imag = -1.0 * ((data[2*i]       * xcos1[i])  +  (data[256-2*i-1] * xsin1[i]));
      }

      //Bit reversed shuffling
      for(i=0; i<128; i++) 
      { 
            k = bit_reverse_512[i];
            if (k < i)
                  swap_cmplx(&buf[i],&buf[k]);
      }

      /* FFT Merge */
      for (m=0; m < 7; m++)
      {
            if(m)
                  two_m = (1 << m);
            else
                  two_m = 1;

            two_m_plus_one = (1 << (m+1));

            for(k = 0; k < two_m; k++)
            {
                  for(i = 0; i < 128; i += two_m_plus_one)
                  {
                        p = k + i;
                        q = p + two_m;
                        tmp_a_r = buf[p].real;
                        tmp_a_i = buf[p].imag;
                        tmp_b_r = buf[q].real * w[m][k].real - buf[q].imag * w[m][k].imag;
                        tmp_b_i = buf[q].imag * w[m][k].real + buf[q].real * w[m][k].imag;
                        buf[p].real = tmp_a_r + tmp_b_r;
                        buf[p].imag =  tmp_a_i + tmp_b_i;
                        buf[q].real = tmp_a_r - tmp_b_r;
                        buf[q].imag =  tmp_a_i - tmp_b_i;

                  }
            }
      }

      /* Post IFFT complex multiply  plus IFFT complex conjugate*/
      for( i=0; i < 128; i++)
      {
            /* y[n] = z[n] * (xcos1[n] + j * xsin1[n]) ; */
            tmp_a_r =        buf[i].real;
            tmp_a_i = -1.0 * buf[i].imag;
            buf[i].real =(tmp_a_r * xcos1[i])  -  (tmp_a_i  * xsin1[i]);
        buf[i].imag =(tmp_a_r * xsin1[i])  +  (tmp_a_i  * xcos1[i]);
      }
      
      data_ptr = data;
      delay_ptr = delay;
      window_ptr = window;

      /* Window and convert to real valued signal */
      for(i=0; i< 64; i++) 
      { 
            *data_ptr++   = 2.0f * (-buf[64+i].imag   * *window_ptr++ + *delay_ptr++); 
            *data_ptr++   = 2.0f * ( buf[64-i-1].real * *window_ptr++ + *delay_ptr++); 
      }

      for(i=0; i< 64; i++) 
      { 
            *data_ptr++  = 2.0f * (-buf[i].real       * *window_ptr++ + *delay_ptr++); 
            *data_ptr++  = 2.0f * ( buf[128-i-1].imag * *window_ptr++ + *delay_ptr++); 
      }
      
      /* The trailing edge of the window goes into the delay line */
      delay_ptr = delay;

      for(i=0; i< 64; i++) 
      { 
            *delay_ptr++  = -buf[64+i].real   * *--window_ptr; 
            *delay_ptr++  =  buf[64-i-1].imag * *--window_ptr; 
      }

      for(i=0; i<64; i++) 
      {
            *delay_ptr++  =  buf[i].imag       * *--window_ptr; 
            *delay_ptr++  = -buf[128-i-1].real * *--window_ptr; 
      }
}

void
imdct_do_256(float data[],float delay[])
{
      int i,k;
      int p,q;
      int m;
      int two_m;
      int two_m_plus_one;

      float tmp_a_i;
      float tmp_a_r;
      float tmp_b_i;
      float tmp_b_r;

      float *data_ptr;
      float *delay_ptr;
      float *window_ptr;

      complex_t *buf_1, *buf_2;

      buf_1 = &buf[0];
      buf_2 = &buf[64];

      /* Pre IFFT complex multiply plus IFFT cmplx conjugate */
      for(k=0; k<64; k++) 
      { 
            /* X1[k] = X[2*k]  */
            /* X2[k] = X[2*k+1]     */

            p = 2 * (128-2*k-1);
            q = 2 * (2 * k);

            /* Z1[k] = (X1[128-2*k-1] + j * X1[2*k]) * (xcos2[k] + j * xsin2[k]); */ 
            buf_1[k].real =         data[p] * xcos2[k] - data[q] * xsin2[k];
        buf_1[k].imag = -1.0f * (data[q] * xcos2[k] + data[p] * xsin2[k]); 
            /* Z2[k] = (X2[128-2*k-1] + j * X2[2*k]) * (xcos2[k] + j * xsin2[k]); */ 
            buf_2[k].real =          data[p + 1] * xcos2[k] - data[q + 1] * xsin2[k];
        buf_2[k].imag = -1.0f * ( data[q + 1] * xcos2[k] + data[p + 1] * xsin2[k]); 
      }

      //IFFT Bit reversed shuffling
      for(i=0; i<64; i++) 
      { 
            k = bit_reverse_256[i];
            if (k < i)
            {
                  swap_cmplx(&buf_1[i],&buf_1[k]);
                  swap_cmplx(&buf_2[i],&buf_2[k]);
            }
      }

      /* FFT Merge */
      for (m=0; m < 6; m++)
      {
            two_m = (1 << m);
            two_m_plus_one = (1 << (m+1));

            //FIXME
            if(m)
                  two_m = (1 << m);
            else
                  two_m = 1;

            for(k = 0; k < two_m; k++)
            {
                  for(i = 0; i < 64; i += two_m_plus_one)
                  {
                        p = k + i;
                        q = p + two_m;
                        //Do block 1
                        tmp_a_r = buf_1[p].real;
                        tmp_a_i = buf_1[p].imag;
                        tmp_b_r = buf_1[q].real * w[m][k].real - buf_1[q].imag * w[m][k].imag;
                        tmp_b_i = buf_1[q].imag * w[m][k].real + buf_1[q].real * w[m][k].imag;
                        buf_1[p].real = tmp_a_r + tmp_b_r;
                        buf_1[p].imag =  tmp_a_i + tmp_b_i;
                        buf_1[q].real = tmp_a_r - tmp_b_r;
                        buf_1[q].imag =  tmp_a_i - tmp_b_i;

                        //Do block 2
                        tmp_a_r = buf_2[p].real;
                        tmp_a_i = buf_2[p].imag;
                        tmp_b_r = buf_2[q].real * w[m][k].real - buf_2[q].imag * w[m][k].imag;
                        tmp_b_i = buf_2[q].imag * w[m][k].real + buf_2[q].real * w[m][k].imag;
                        buf_2[p].real = tmp_a_r + tmp_b_r;
                        buf_2[p].imag =  tmp_a_i + tmp_b_i;
                        buf_2[q].real = tmp_a_r - tmp_b_r;
                        buf_2[q].imag =  tmp_a_i - tmp_b_i;

                  }
            }
      }

      /* Post IFFT complex multiply */
      for( i=0; i < 64; i++)
      {
            /* y1[n] = z1[n] * (xcos2[n] + j * xs in2[n]) ; */ 
            tmp_a_r =  buf_1[i].real;
            tmp_a_i = -buf_1[i].imag;
            buf_1[i].real =(tmp_a_r * xcos2[i])  -  (tmp_a_i  * xsin2[i]);
        buf_1[i].imag =(tmp_a_r * xsin2[i])  +  (tmp_a_i  * xcos2[i]);
            /* y2[n] = z2[n] * (xcos2[n] + j * xsin2[n]) ; */ 
            tmp_a_r =  buf_2[i].real;
            tmp_a_i = -buf_2[i].imag;
            buf_2[i].real =(tmp_a_r * xcos2[i])  -  (tmp_a_i  * xsin2[i]);
        buf_2[i].imag =(tmp_a_r * xsin2[i])  +  (tmp_a_i  * xcos2[i]);
      }
      
      data_ptr = data;
      delay_ptr = delay;
      window_ptr = window;

      /* Window and convert to real valued signal */
      for(i=0; i< 64; i++) 
      { 
            *data_ptr++  = 2.0f * (-buf_1[i].imag      * *window_ptr++ + *delay_ptr++);
            *data_ptr++  = 2.0f * ( buf_1[64-i-1].real * *window_ptr++ + *delay_ptr++);
      }

      for(i=0; i< 64; i++) 
      {
            *data_ptr++  = 2.0f * (-buf_1[i].real      * *window_ptr++ + *delay_ptr++);
            *data_ptr++  = 2.0f * ( buf_1[64-i-1].imag * *window_ptr++ + *delay_ptr++);
      }
      
      delay_ptr = delay;

      for(i=0; i< 64; i++) 
      {
            *delay_ptr++ = -buf_2[i].real      * *--window_ptr;
            *delay_ptr++ =  buf_2[64-i-1].imag * *--window_ptr;
      }

      for(i=0; i< 64; i++) 
      {
            *delay_ptr++ =  buf_2[i].imag      * *--window_ptr;
            *delay_ptr++ = -buf_2[64-i-1].real * *--window_ptr;
      }
}

//FIXME remove - for timing code
///#include <sys/time.h>
//FIXME remove

void 
imdct(bsi_t *bsi,audblk_t *audblk, stream_samples_t samples) {
      int i;

      //handy timing code
      //struct timeval start,end;

      //gettimeofday(&start,0);
      
      for(i=0; i<bsi->nfchans;i++)
      {
            if(audblk->blksw[i])
                  imdct_do_256(samples[i],delay[i]);
            else
                  imdct_do_512(samples[i],delay[i]);
      }
      //gettimeofday(&end,0);
      //printf("imdct %ld us\n",(end.tv_sec - start.tv_sec) * 1000000 +
        //end.tv_usec - start.tv_usec);

      //XXX We don't bother with the IMDCT for the LFE as it's currently
      //unused.
      //if (bsi->lfeon)
      //    imdct_do_512(coeffs->lfe,samples->channel[5],delay[5]);
      //    
}

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