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FFmpeg/libavcodec/liba52/imdct.c
Fabrice Bellard 3519af27d8 when changing version, please keep my changes (win32 compile fix) 
Originally committed as revision 2138 to svn://svn.ffmpeg.org/ffmpeg/trunk
2003-08-24 13:57:42 +00:00

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/*
* imdct.c
* Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
* Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
*
* The ifft algorithms in this file have been largely inspired by Dan
* Bernstein's work, djbfft, available at http://cr.yp.to/djbfft.html
*
* This file is part of a52dec, a free ATSC A-52 stream decoder.
* See http://liba52.sourceforge.net/ for updates.
*
* a52dec 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 of the License, or
* (at your option) any later version.
*
* a52dec 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "a52.h"
#include "a52_internal.h"
#include "mm_accel.h"
typedef struct complex_s {
sample_t real;
sample_t imag;
} complex_t;
static uint8_t fftorder[] = {
0,128, 64,192, 32,160,224, 96, 16,144, 80,208,240,112, 48,176,
8,136, 72,200, 40,168,232,104,248,120, 56,184, 24,152,216, 88,
4,132, 68,196, 36,164,228,100, 20,148, 84,212,244,116, 52,180,
252,124, 60,188, 28,156,220, 92, 12,140, 76,204,236,108, 44,172,
2,130, 66,194, 34,162,226, 98, 18,146, 82,210,242,114, 50,178,
10,138, 74,202, 42,170,234,106,250,122, 58,186, 26,154,218, 90,
254,126, 62,190, 30,158,222, 94, 14,142, 78,206,238,110, 46,174,
6,134, 70,198, 38,166,230,102,246,118, 54,182, 22,150,214, 86
};
/* Root values for IFFT */
static sample_t roots16[3];
static sample_t roots32[7];
static sample_t roots64[15];
static sample_t roots128[31];
/* Twiddle factors for IMDCT */
static complex_t pre1[128];
static complex_t post1[64];
static complex_t pre2[64];
static complex_t post2[32];
static sample_t a52_imdct_window[256];
static void (* ifft128) (complex_t * buf);
static void (* ifft64) (complex_t * buf);
static inline void ifft2 (complex_t * buf)
{
sample_t r, i;
r = buf[0].real;
i = buf[0].imag;
buf[0].real += buf[1].real;
buf[0].imag += buf[1].imag;
buf[1].real = r - buf[1].real;
buf[1].imag = i - buf[1].imag;
}
static inline void ifft4 (complex_t * buf)
{
sample_t tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
tmp1 = buf[0].real + buf[1].real;
tmp2 = buf[3].real + buf[2].real;
tmp3 = buf[0].imag + buf[1].imag;
tmp4 = buf[2].imag + buf[3].imag;
tmp5 = buf[0].real - buf[1].real;
tmp6 = buf[0].imag - buf[1].imag;
tmp7 = buf[2].imag - buf[3].imag;
tmp8 = buf[3].real - buf[2].real;
buf[0].real = tmp1 + tmp2;
buf[0].imag = tmp3 + tmp4;
buf[2].real = tmp1 - tmp2;
buf[2].imag = tmp3 - tmp4;
buf[1].real = tmp5 + tmp7;
buf[1].imag = tmp6 + tmp8;
buf[3].real = tmp5 - tmp7;
buf[3].imag = tmp6 - tmp8;
}
/* basic radix-2 ifft butterfly */
#define BUTTERFLY_0(t0,t1,W0,W1,d0,d1) do { \
t0 = MUL (W1, d1) + MUL (W0, d0); \
t1 = MUL (W0, d1) - MUL (W1, d0); \
} while (0)
/* radix-2 ifft butterfly with bias */
#define BUTTERFLY_B(t0,t1,W0,W1,d0,d1) do { \
t0 = BIAS (MUL (d1, W1) + MUL (d0, W0)); \
t1 = BIAS (MUL (d1, W0) - MUL (d0, W1)); \
} while (0)
/* the basic split-radix ifft butterfly */
#define BUTTERFLY(a0,a1,a2,a3,wr,wi) do { \
BUTTERFLY_0 (tmp5, tmp6, wr, wi, a2.real, a2.imag); \
BUTTERFLY_0 (tmp8, tmp7, wr, wi, a3.imag, a3.real); \
tmp1 = tmp5 + tmp7; \
tmp2 = tmp6 + tmp8; \
tmp3 = tmp6 - tmp8; \
tmp4 = tmp7 - tmp5; \
a2.real = a0.real - tmp1; \
a2.imag = a0.imag - tmp2; \
a3.real = a1.real - tmp3; \
a3.imag = a1.imag - tmp4; \
a0.real += tmp1; \
a0.imag += tmp2; \
a1.real += tmp3; \
a1.imag += tmp4; \
} while (0)
/* split-radix ifft butterfly, specialized for wr=1 wi=0 */
#define BUTTERFLY_ZERO(a0,a1,a2,a3) do { \
tmp1 = a2.real + a3.real; \
tmp2 = a2.imag + a3.imag; \
tmp3 = a2.imag - a3.imag; \
tmp4 = a3.real - a2.real; \
a2.real = a0.real - tmp1; \
a2.imag = a0.imag - tmp2; \
a3.real = a1.real - tmp3; \
a3.imag = a1.imag - tmp4; \
a0.real += tmp1; \
a0.imag += tmp2; \
a1.real += tmp3; \
a1.imag += tmp4; \
} while (0)
/* split-radix ifft butterfly, specialized for wr=wi */
#define BUTTERFLY_HALF(a0,a1,a2,a3,w) do { \
tmp5 = MUL (a2.real + a2.imag, w); \
tmp6 = MUL (a2.imag - a2.real, w); \
tmp7 = MUL (a3.real - a3.imag, w); \
tmp8 = MUL (a3.imag + a3.real, w); \
tmp1 = tmp5 + tmp7; \
tmp2 = tmp6 + tmp8; \
tmp3 = tmp6 - tmp8; \
tmp4 = tmp7 - tmp5; \
a2.real = a0.real - tmp1; \
a2.imag = a0.imag - tmp2; \
a3.real = a1.real - tmp3; \
a3.imag = a1.imag - tmp4; \
a0.real += tmp1; \
a0.imag += tmp2; \
a1.real += tmp3; \
a1.imag += tmp4; \
} while (0)
static inline void ifft8 (complex_t * buf)
{
sample_t tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
ifft4 (buf);
ifft2 (buf + 4);
ifft2 (buf + 6);
BUTTERFLY_ZERO (buf[0], buf[2], buf[4], buf[6]);
BUTTERFLY_HALF (buf[1], buf[3], buf[5], buf[7], roots16[1]);
}
static void ifft_pass (complex_t * buf, sample_t * weight, int n)
{
complex_t * buf1;
complex_t * buf2;
complex_t * buf3;
sample_t tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
int i;
buf++;
buf1 = buf + n;
buf2 = buf + 2 * n;
buf3 = buf + 3 * n;
BUTTERFLY_ZERO (buf[-1], buf1[-1], buf2[-1], buf3[-1]);
i = n - 1;
do {
BUTTERFLY (buf[0], buf1[0], buf2[0], buf3[0],
weight[0], weight[2*i-n]);
buf++;
buf1++;
buf2++;
buf3++;
weight++;
} while (--i);
}
static void ifft16 (complex_t * buf)
{
ifft8 (buf);
ifft4 (buf + 8);
ifft4 (buf + 12);
ifft_pass (buf, roots16, 4);
}
static void ifft32 (complex_t * buf)
{
ifft16 (buf);
ifft8 (buf + 16);
ifft8 (buf + 24);
ifft_pass (buf, roots32, 8);
}
static void ifft64_c (complex_t * buf)
{
ifft32 (buf);
ifft16 (buf + 32);
ifft16 (buf + 48);
ifft_pass (buf, roots64, 16);
}
static void ifft128_c (complex_t * buf)
{
ifft32 (buf);
ifft16 (buf + 32);
ifft16 (buf + 48);
ifft_pass (buf, roots64, 16);
ifft32 (buf + 64);
ifft32 (buf + 96);
ifft_pass (buf, roots128, 32);
}
void a52_imdct_512 (sample_t * data, sample_t * delay, sample_t bias)
{
int i, k;
sample_t t_r, t_i, a_r, a_i, b_r, b_i, w_1, w_2;
const sample_t * window = a52_imdct_window;
complex_t buf[128];
for (i = 0; i < 128; i++) {
k = fftorder[i];
t_r = pre1[i].real;
t_i = pre1[i].imag;
BUTTERFLY_0 (buf[i].real, buf[i].imag, t_r, t_i, data[k], data[255-k]);
}
ifft128 (buf);
/* Post IFFT complex multiply plus IFFT complex conjugate*/
/* Window and convert to real valued signal */
for (i = 0; i < 64; i++) {
/* y[n] = z[n] * (xcos1[n] + j * xsin1[n]) ; */
t_r = post1[i].real;
t_i = post1[i].imag;
BUTTERFLY_0 (a_r, a_i, t_i, t_r, buf[i].imag, buf[i].real);
BUTTERFLY_0 (b_r, b_i, t_r, t_i, buf[127-i].imag, buf[127-i].real);
w_1 = window[2*i];
w_2 = window[255-2*i];
BUTTERFLY_B (data[255-2*i], data[2*i], w_2, w_1, a_r, delay[2*i]);
delay[2*i] = a_i;
w_1 = window[2*i+1];
w_2 = window[254-2*i];
BUTTERFLY_B (data[2*i+1], data[254-2*i], w_1, w_2, b_r, delay[2*i+1]);
delay[2*i+1] = b_i;
}
}
void a52_imdct_256 (sample_t * data, sample_t * delay, sample_t bias)
{
int i, k;
sample_t t_r, t_i, a_r, a_i, b_r, b_i, c_r, c_i, d_r, d_i, w_1, w_2;
const sample_t * window = a52_imdct_window;
complex_t buf1[64], buf2[64];
/* Pre IFFT complex multiply plus IFFT cmplx conjugate */
for (i = 0; i < 64; i++) {
k = fftorder[i];
t_r = pre2[i].real;
t_i = pre2[i].imag;
BUTTERFLY_0 (buf1[i].real, buf1[i].imag, t_r, t_i, data[k], data[254-k]);
BUTTERFLY_0 (buf2[i].real, buf2[i].imag, t_r, t_i, data[k+1], data[255-k]);
}
ifft64 (buf1);
ifft64 (buf2);
/* Post IFFT complex multiply */
/* Window and convert to real valued signal */
for (i = 0; i < 32; i++) {
/* y1[n] = z1[n] * (xcos2[n] + j * xs in2[n]) ; */
t_r = post2[i].real;
t_i = post2[i].imag;
BUTTERFLY_0 (a_r, a_i, t_i, t_r, buf1[i].imag, buf1[i].real);
BUTTERFLY_0 (b_r, b_i, t_r, t_i, buf1[63-i].imag, buf1[63-i].real);
BUTTERFLY_0 (c_r, c_i, t_i, t_r, buf2[i].imag, buf2[i].real);
BUTTERFLY_0 (d_r, d_i, t_r, t_i, buf2[63-i].imag, buf2[63-i].real);
w_1 = window[2*i];
w_2 = window[255-2*i];
BUTTERFLY_B (data[255-2*i], data[2*i], w_2, w_1, a_r, delay[2*i]);
delay[2*i] = c_i;
w_1 = window[128+2*i];
w_2 = window[127-2*i];
BUTTERFLY_B (data[128+2*i], data[127-2*i], w_1, w_2, a_i, delay[127-2*i]);
delay[127-2*i] = c_r;
w_1 = window[2*i+1];
w_2 = window[254-2*i];
BUTTERFLY_B (data[254-2*i], data[2*i+1], w_2, w_1, b_i, delay[2*i+1]);
delay[2*i+1] = d_r;
w_1 = window[129+2*i];
w_2 = window[126-2*i];
BUTTERFLY_B (data[129+2*i], data[126-2*i], w_1, w_2, b_r, delay[126-2*i]);
delay[126-2*i] = d_i;
}
}
static double besselI0 (double x)
{
double bessel = 1;
int i = 100;
do
bessel = bessel * x / (i * i) + 1;
while (--i);
return bessel;
}
void a52_imdct_init (uint32_t mm_accel)
{
int i, k;
double sum;
double local_imdct_window[256];
/* compute imdct window - kaiser-bessel derived window, alpha = 5.0 */
sum = 0;
for (i = 0; i < 256; i++) {
sum += besselI0 (i * (256 - i) * (5 * M_PI / 256) * (5 * M_PI / 256));
local_imdct_window[i] = sum;
}
sum++;
for (i = 0; i < 256; i++)
a52_imdct_window[i] = SAMPLE (sqrt (local_imdct_window[i] / sum));
for (i = 0; i < 3; i++)
roots16[i] = SAMPLE (cos ((M_PI / 8) * (i + 1)));
for (i = 0; i < 7; i++)
roots32[i] = SAMPLE (cos ((M_PI / 16) * (i + 1)));
for (i = 0; i < 15; i++)
roots64[i] = SAMPLE (cos ((M_PI / 32) * (i + 1)));
for (i = 0; i < 31; i++)
roots128[i] = SAMPLE (cos ((M_PI / 64) * (i + 1)));
for (i = 0; i < 64; i++) {
k = fftorder[i] / 2 + 64;
pre1[i].real = SAMPLE (cos ((M_PI / 256) * (k - 0.25)));
pre1[i].imag = SAMPLE (sin ((M_PI / 256) * (k - 0.25)));
}
for (i = 64; i < 128; i++) {
k = fftorder[i] / 2 + 64;
pre1[i].real = SAMPLE (-cos ((M_PI / 256) * (k - 0.25)));
pre1[i].imag = SAMPLE (-sin ((M_PI / 256) * (k - 0.25)));
}
for (i = 0; i < 64; i++) {
post1[i].real = SAMPLE (cos ((M_PI / 256) * (i + 0.5)));
post1[i].imag = SAMPLE (sin ((M_PI / 256) * (i + 0.5)));
}
for (i = 0; i < 64; i++) {
k = fftorder[i] / 4;
pre2[i].real = SAMPLE (cos ((M_PI / 128) * (k - 0.25)));
pre2[i].imag = SAMPLE (sin ((M_PI / 128) * (k - 0.25)));
}
for (i = 0; i < 32; i++) {
post2[i].real = SAMPLE (cos ((M_PI / 128) * (i + 0.5)));
post2[i].imag = SAMPLE (sin ((M_PI / 128) * (i + 0.5)));
}
#ifdef LIBA52_DJBFFT
if (mm_accel & MM_ACCEL_DJBFFT) {
ifft128 = (void (*) (complex_t *)) fftc4_un128;
ifft64 = (void (*) (complex_t *)) fftc4_un64;
} else
#endif
{
ifft128 = ifft128_c;
ifft64 = ifft64_c;
}
}
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