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/*
* 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 "downmix.h"
#include "imdct_c.h"
#include "srfft.h"
#define N 512
extern void (*imdct_do_512) (float data[],float delay[]);
extern void (*imdct_do_512_nol) (float data[], float delay[]);
extern void (*fft_64p) (complex_t *);
extern const int pm128[];
extern float window[];
extern complex_t buf[128];
extern void fft_64p_c (complex_t *);
extern void fft_128p_c (complex_t *);
static void imdct_do_512_c (float data[],float delay[]);
static void imdct_do_512_nol_c (float data[], float delay[]);
/* Twiddle factors for IMDCT */
static float xcos1[128] __attribute__((aligned(16)));
static float xsin1[128] __attribute__((aligned(16)));
int imdct_init_c (void)
{
int i;
float scale = 255.99609372;
imdct_do_512 = imdct_do_512_c;
imdct_do_512_nol = imdct_do_512_nol_c;
fft_64p = fft_64p_c;
/* 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)) * scale;
xsin1[i] = sin(2.0f * M_PI * (8*i+1)/(8*N)) * scale;
}
return 0;
}
static void imdct_do_512_c (float data[], float delay[])
{
int i, j;
float tmp_a_r, tmp_a_i;
float *data_ptr;
float *delay_ptr;
float *window_ptr;
// 512 IMDCT with source and dest data in 'data'
// Pre IFFT complex multiply plus IFFT complex conjugate
for( i=0; i < 128; i++) {
j = pm128[i];
//a = (data[256-2*j-1] - data[2*j]) * (xcos1[j] + xsin1[j]);
//c = data[2*j] * xcos1[j];
//b = data[256-2*j-1] * xsin1[j];
//buf1[i].re = a - b + c;
//buf1[i].im = b + c;
buf[i].re = (data[256-2*j-1] * xcos1[j]) - (data[2*j] * xsin1[j]);
buf[i].im = -1.0 * (data[2*j] * xcos1[j] + data[256-2*j-1] * xsin1[j]);
}
fft_128p_c (&buf[0]);
// Post IFFT complex multiply plus IFFT complex conjugate
for (i=0; i < 128; i++) {
tmp_a_r = buf[i].re;
tmp_a_i = buf[i].im;
//a = (tmp_a_r - tmp_a_i) * (xcos1[j] + xsin1[j]);
//b = tmp_a_r * xsin1[j];
//c = tmp_a_i * xcos1[j];
//buf[j].re = a - b + c;
//buf[j].im = b + c;
buf[i].re =(tmp_a_r * xcos1[i]) + (tmp_a_i * xsin1[i]);
buf[i].im =(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++ = -buf[64+i].im * *window_ptr++ + *delay_ptr++;
*data_ptr++ = buf[64-i-1].re * *window_ptr++ + *delay_ptr++;
}
for(i=0; i< 64; i++) {
*data_ptr++ = -buf[i].re * *window_ptr++ + *delay_ptr++;
*data_ptr++ = buf[128-i-1].im * *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].re * *--window_ptr;
*delay_ptr++ = buf[64-i-1].im * *--window_ptr;
}
for(i=0; i<64; i++) {
*delay_ptr++ = buf[i].im * *--window_ptr;
*delay_ptr++ = -buf[128-i-1].re * *--window_ptr;
}
}
static void imdct_do_512_nol_c (float data[], float delay[])
{
int i, j;
float tmp_a_i;
float tmp_a_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]) */
j = pm128[i];
//a = (data[256-2*j-1] - data[2*j]) * (xcos1[j] + xsin1[j]);
//c = data[2*j] * xcos1[j];
//b = data[256-2*j-1] * xsin1[j];
//buf1[i].re = a - b + c;
//buf1[i].im = b + c;
buf[i].re = (data[256-2*j-1] * xcos1[j]) - (data[2*j] * xsin1[j]);
buf[i].im = -1.0 * (data[2*j] * xcos1[j] + data[256-2*j-1] * xsin1[j]);
}
fft_128p_c (&buf[0]);
/* Post IFFT complex multiply plus IFFT complex conjugate*/
for (i=0; i < 128; i++) {
/* y[n] = z[n] * (xcos1[n] + j * xsin1[n]) ; */
/* int j1 = i; */
tmp_a_r = buf[i].re;
tmp_a_i = buf[i].im;
//a = (tmp_a_r - tmp_a_i) * (xcos1[j] + xsin1[j]);
//b = tmp_a_r * xsin1[j];
//c = tmp_a_i * xcos1[j];
//buf[j].re = a - b + c;
//buf[j].im = b + c;
buf[i].re =(tmp_a_r * xcos1[i]) + (tmp_a_i * xsin1[i]);
buf[i].im =(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, no overlap here*/
for (i=0; i< 64; i++) {
*data_ptr++ = -buf[64+i].im * *window_ptr++;
*data_ptr++ = buf[64-i-1].re * *window_ptr++;
}
for(i=0; i< 64; i++) {
*data_ptr++ = -buf[i].re * *window_ptr++;
*data_ptr++ = buf[128-i-1].im * *window_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].re * *--window_ptr;
*delay_ptr++ = buf[64-i-1].im * *--window_ptr;
}
for(i=0; i<64; i++) {
*delay_ptr++ = buf[i].im * *--window_ptr;
*delay_ptr++ = -buf[128-i-1].re * *--window_ptr;
}
}
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