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vdr/ac3dec/srfft.c
2001-08-09 11:41:39 +02:00

306 lines
6.4 KiB
C

/*
* srfft.c
*
* Copyright (C) Yuqing Deng <Yuqing_Deng@brown.edu> - April 2000
*
* 64 and 128 point split radix fft for ac3dec
*
* The algorithm is desribed in the book:
* "Computational Frameworks of the Fast Fourier Transform".
*
* The ideas and the the organization of code borrowed from djbfft written by
* D. J. Bernstein <djb@cr.py.to>. djbff can be found at
* http://cr.yp.to/djbfft.html.
*
* srfft.c 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.
*
* srfft.c 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 <stdio.h>
#include "srfft.h"
#include "srfftp.h"
void fft_8 (complex_t *x);
void fft_4(complex_t *x)
{
/* delta_p = 1 here */
/* x[k] = sum_{i=0..3} x[i] * w^{i*k}, w=e^{-2*pi/4}
*/
register float yt_r, yt_i, yb_r, yb_i, u_r, u_i, vi_r, vi_i;
yt_r = x[0].re;
yb_r = yt_r - x[2].re;
yt_r += x[2].re;
u_r = x[1].re;
vi_i = x[3].re - u_r;
u_r += x[3].re;
u_i = x[1].im;
vi_r = u_i - x[3].im;
u_i += x[3].im;
yt_i = yt_r;
yt_i += u_r;
x[0].re = yt_i;
yt_r -= u_r;
x[2].re = yt_r;
yt_i = yb_r;
yt_i += vi_r;
x[1].re = yt_i;
yb_r -= vi_r;
x[3].re = yb_r;
yt_i = x[0].im;
yb_i = yt_i - x[2].im;
yt_i += x[2].im;
yt_r = yt_i;
yt_r += u_i;
x[0].im = yt_r;
yt_i -= u_i;
x[2].im = yt_i;
yt_r = yb_i;
yt_r += vi_i;
x[1].im = yt_r;
yb_i -= vi_i;
x[3].im = yb_i;
}
void fft_8 (complex_t *x)
{
/* delta_p = diag{1, sqrt(i)} here */
/* x[k] = sum_{i=0..7} x[i] * w^{i*k}, w=e^{-2*pi/8}
*/
register float wT1_r, wT1_i, wB1_r, wB1_i, wT2_r, wT2_i, wB2_r, wB2_i;
wT1_r = x[1].re;
wT1_i = x[1].im;
wB1_r = x[3].re;
wB1_i = x[3].im;
x[1] = x[2];
x[2] = x[4];
x[3] = x[6];
fft_4(&x[0]);
/* x[0] x[4] */
wT2_r = x[5].re;
wT2_r += x[7].re;
wT2_r += wT1_r;
wT2_r += wB1_r;
wT2_i = wT2_r;
wT2_r += x[0].re;
wT2_i = x[0].re - wT2_i;
x[0].re = wT2_r;
x[4].re = wT2_i;
wT2_i = x[5].im;
wT2_i += x[7].im;
wT2_i += wT1_i;
wT2_i += wB1_i;
wT2_r = wT2_i;
wT2_r += x[0].im;
wT2_i = x[0].im - wT2_i;
x[0].im = wT2_r;
x[4].im = wT2_i;
/* x[2] x[6] */
wT2_r = x[5].im;
wT2_r -= x[7].im;
wT2_r += wT1_i;
wT2_r -= wB1_i;
wT2_i = wT2_r;
wT2_r += x[2].re;
wT2_i = x[2].re - wT2_i;
x[2].re = wT2_r;
x[6].re = wT2_i;
wT2_i = x[5].re;
wT2_i -= x[7].re;
wT2_i += wT1_r;
wT2_i -= wB1_r;
wT2_r = wT2_i;
wT2_r += x[2].im;
wT2_i = x[2].im - wT2_i;
x[2].im = wT2_i;
x[6].im = wT2_r;
/* x[1] x[5] */
wT2_r = wT1_r;
wT2_r += wB1_i;
wT2_r -= x[5].re;
wT2_r -= x[7].im;
wT2_i = wT1_i;
wT2_i -= wB1_r;
wT2_i -= x[5].im;
wT2_i += x[7].re;
wB2_r = wT2_r;
wB2_r += wT2_i;
wT2_i -= wT2_r;
wB2_r *= HSQRT2;
wT2_i *= HSQRT2;
wT2_r = wB2_r;
wB2_r += x[1].re;
wT2_r = x[1].re - wT2_r;
wB2_i = x[5].re;
x[1].re = wB2_r;
x[5].re = wT2_r;
wT2_r = wT2_i;
wT2_r += x[1].im;
wT2_i = x[1].im - wT2_i;
wB2_r = x[5].im;
x[1].im = wT2_r;
x[5].im = wT2_i;
/* x[3] x[7] */
wT1_r -= wB1_i;
wT1_i += wB1_r;
wB1_r = wB2_i - x[7].im;
wB1_i = wB2_r + x[7].re;
wT1_r -= wB1_r;
wT1_i -= wB1_i;
wB1_r = wT1_r + wT1_i;
wB1_r *= HSQRT2;
wT1_i -= wT1_r;
wT1_i *= HSQRT2;
wB2_r = x[3].re;
wB2_i = wB2_r + wT1_i;
wB2_r -= wT1_i;
x[3].re = wB2_i;
x[7].re = wB2_r;
wB2_i = x[3].im;
wB2_r = wB2_i + wB1_r;
wB2_i -= wB1_r;
x[3].im = wB2_i;
x[7].im = wB2_r;
}
void fft_asmb(int k, complex_t *x, complex_t *wTB,
const complex_t *d, const complex_t *d_3)
{
register complex_t *x2k, *x3k, *x4k, *wB;
register float a_r, a_i, a1_r, a1_i, u_r, u_i, v_r, v_i;
x2k = x + 2 * k;
x3k = x2k + 2 * k;
x4k = x3k + 2 * k;
wB = wTB + 2 * k;
TRANSZERO(x[0],x2k[0],x3k[0],x4k[0]);
TRANS(x[1],x2k[1],x3k[1],x4k[1],wTB[1],wB[1],d[1],d_3[1]);
--k;
for(;;) {
TRANS(x[2],x2k[2],x3k[2],x4k[2],wTB[2],wB[2],d[2],d_3[2]);
TRANS(x[3],x2k[3],x3k[3],x4k[3],wTB[3],wB[3],d[3],d_3[3]);
if (!--k) break;
x += 2;
x2k += 2;
x3k += 2;
x4k += 2;
d += 2;
d_3 += 2;
wTB += 2;
wB += 2;
}
}
void fft_asmb16(complex_t *x, complex_t *wTB)
{
register float a_r, a_i, a1_r, a1_i, u_r, u_i, v_r, v_i;
int k = 2;
/* transform x[0], x[8], x[4], x[12] */
TRANSZERO(x[0],x[4],x[8],x[12]);
/* transform x[1], x[9], x[5], x[13] */
TRANS(x[1],x[5],x[9],x[13],wTB[1],wTB[5],delta16[1],delta16_3[1]);
/* transform x[2], x[10], x[6], x[14] */
TRANSHALF_16(x[2],x[6],x[10],x[14]);
/* transform x[3], x[11], x[7], x[15] */
TRANS(x[3],x[7],x[11],x[15],wTB[3],wTB[7],delta16[3],delta16_3[3]);
}
void fft_64p_c (complex_t *a)
{
fft_8(&a[0]); fft_4(&a[8]); fft_4(&a[12]);
fft_asmb16(&a[0], &a[8]);
fft_8(&a[16]), fft_8(&a[24]);
fft_asmb(4, &a[0], &a[16],&delta32[0], &delta32_3[0]);
fft_8(&a[32]); fft_4(&a[40]); fft_4(&a[44]);
fft_asmb16(&a[32], &a[40]);
fft_8(&a[48]); fft_4(&a[56]); fft_4(&a[60]);
fft_asmb16(&a[48], &a[56]);
fft_asmb(8, &a[0], &a[32],&delta64[0], &delta64_3[0]);
}
void fft_128p_c (complex_t *a)
{
fft_8(&a[0]); fft_4(&a[8]); fft_4(&a[12]);
fft_asmb16(&a[0], &a[8]);
fft_8(&a[16]), fft_8(&a[24]);
fft_asmb(4, &a[0], &a[16],&delta32[0], &delta32_3[0]);
fft_8(&a[32]); fft_4(&a[40]); fft_4(&a[44]);
fft_asmb16(&a[32], &a[40]);
fft_8(&a[48]); fft_4(&a[56]); fft_4(&a[60]);
fft_asmb16(&a[48], &a[56]);
fft_asmb(8, &a[0], &a[32],&delta64[0], &delta64_3[0]);
fft_8(&a[64]); fft_4(&a[72]); fft_4(&a[76]);
/* fft_16(&a[64]); */
fft_asmb16(&a[64], &a[72]);
fft_8(&a[80]); fft_8(&a[88]);
/* fft_32(&a[64]); */
fft_asmb(4, &a[64], &a[80],&delta32[0], &delta32_3[0]);
fft_8(&a[96]); fft_4(&a[104]), fft_4(&a[108]);
/* fft_16(&a[96]); */
fft_asmb16(&a[96], &a[104]);
fft_8(&a[112]), fft_8(&a[120]);
/* fft_32(&a[96]); */
fft_asmb(4, &a[96], &a[112], &delta32[0], &delta32_3[0]);
/* fft_128(&a[0]); */
fft_asmb(16, &a[0], &a[64], &delta128[0], &delta128_3[0]);
}