/* * 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 */
// ifft128 and ifft64 always maps to C code by Picard 12/11/2004
#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);#define ifft128 ifft128_c
#define ifft64 ifft64_c
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;    }*/
}