/*  *  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 "decode.h"#include "imdct.h"void imdct_do_256(float x[],float y[],float delay[]);void imdct_do_512(float x[],float y[],float delay[]);typedef struct complex_s{	float real;	float imag;} complex_t;#define N 512static complex_t buf[N/4];/* 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};/* 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[N/4];static float xsin1[N/4];static float xcos2[N/8];static float xsin2[N/8];/* 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 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 < N/4; i++)	{		xcos1[i] = -cos(2 * M_PI * (8*i+1)/(8*N)) ; 		xsin1[i] = -sin(2 * M_PI * (8*i+1)/(8*N)) ;	}		/* More twiddle factors to turn IFFT into IMDCT */	for( i=0; i < N/8; i++)	{		xcos2[i] = -cos(2 * M_PI * (8*i+1)/(4*N)) ; 		xsin2[i] = -sin(2 * 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(bsi_t *bsi,audblk_t *audblk, 		stream_coeffs_t *coeffs, stream_samples_t *samples){	int i;	for(i=0; i<bsi->nfchans;i++)	{		if(audblk->blksw[i])			imdct_do_256(coeffs->fbw[i],samples->channel[i],delay[i]);		else			imdct_do_512(coeffs->fbw[i],samples->channel[i],delay[i]);	}	//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]);	//	}voidimdct_do_512(float x[],float y[],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;	/* Pre IFFT complex multiply plus IFFT cmplx conjugate */	for( i=0; i < N/4; i++)	{		/* z[i] = (X[N/2-2*i-1] + j * X[2*i]) * (xcos1[i] + j * xsin1[i]) ; */ 		buf[i].real =         (x[N/2-2*i-1] * xcos1[i])  -  (x[2*i]       * xsin1[i]);	  buf[i].imag = -1.0 * ((x[2*i]       * xcos1[i])  +  (x[N/2-2*i-1] * xsin1[i]));	}	//Bit reversed shuffling	for(i=0; i<N/4; i++) 	{ 		k = bit_reverse_512[i];		if (k < i)			swap_cmplx(&buf[i],&buf[k]);	}	/* FFT Merge */	for (m=0; m < 7; m++)	{		two_m = (1 << m);		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 < N/4; 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]);	}		/* Window and convert to real valued signal */	for(i=0; i<N/8; i++) 	{ 		y[0   + 2*i]   = -buf[N/8+i].imag   * window[0   + 2*i]; 		y[0   + 2*i+1] =  buf[N/8-i-1].real * window[0   + 2*i+1]; 		y[128 + 2*i]   = -buf[i].real       * window[128 + 2*i]; 		y[128 + 2*i+1] =  buf[N/4-i-1].imag * window[128 + 2*i+1]; 		y[256 + 2*i]   = -buf[N/8+i].real   * window[256 - 2*i-1];		y[256 + 2*i+1] =  buf[N/8-i-1].imag * window[256 - 2*i-2];		y[384 + 2*i]   =  buf[i].imag       * window[128 - 2*i-1];		y[384 + 2*i+1] = -buf[N/4-i-1].real * window[128 - 2*i-2];	}	/* Overlap and add */	for(i=0; i< 256; i++) 	{ 		y[i] = 2.0 * (y[i] + delay[i]); 		delay[i] = y[256 +i]; 	}}voidimdct_do_256(float x[],float y[],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;	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<N/8; k++) 	{ 		/* X1[k] = X[2*k]  */		/* X2[k] = X[2*k+1]     */		p = 2 * (N/4-2*k-1);		q = 2 * (2 * k);		/* Z1[k] = (X1[N/4-2*k-1] + j * X1[2*k]) * (xcos2[k] + j * xsin2[k]); */ 		buf_1[k].real =         x[p] * xcos2[k] - x[q] * xsin2[k];	  buf_1[k].imag = -1.0 * (x[q] * xcos2[k] + x[p] * xsin2[k]); 		/* Z2[k] = (X2[N/4-2*k-1] + j * X2[2*k]) * (xcos2[k] + j * xsin2[k]); */ 		buf_2[k].real =          x[p + 1] * xcos2[k] - x[q + 1] * xsin2[k];	  buf_2[k].imag = -1.0 * ( x[q + 1] * xcos2[k] + x[p + 1] * xsin2[k]); 	}	//IFFT Bit reversed shuffling	for(i=0; i<N/8; 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));		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 < N/8; i++)	{		/* y1[n] = z1[n] * (xcos2[n] + j * xs in2[n]) ; */ 		tmp_a_r =        buf_1[i].real;		tmp_a_i = -1.0 * 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 = -1.0 * 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]);	}		/* Window and convert to real valued signal */	for(i=0; i<N/8; i++) 	{ 		y[2*i]        = -buf_1[i].imag       * window[2*i];		y[2*i+1]      =  buf_1[N/8-i-1].real * window[2*i+1]; 		y[N/4+2*i]    = -buf_1[i].real       * window[N/4+2*i]; 		y[N/4+2*i+1]  =  buf_1[N/8-i-1].imag * window[N/4+2*i+1];		y[N/2+2*i]    = -buf_2[i].real       * window[N/2-2*i-1]; 		y[N/2+2*i+1]  =  buf_2[N/8-i-1].imag * window[N/2-2*i-2]; 		y[3*N/4+2*i]   =  buf_2[i].imag       * window[N/4-2*i-1]; 		y[3*N/4+2*i+1] = -buf_2[N/8-i-1].real * window[N/4-2*i-2]; 	}		/* Overlap and add */	for(i=0; i<N/2; i++) 	{ 		y[i] = 2 * (y[i] + delay[i]); 		delay[i] = y[N/2+i]; 	}}