FFmpeg/libavcodec/libac3/imdct.c

/* 
 *  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 "../common.h"
#include <math.h>
#include "ac3.h"
#include "ac3_internal.h"

void (* imdct_256) (float data[], float delay[]);
void (* imdct_512) (float data[], float delay[]);

typedef struct complex_s
{
    float real;
    float imag;
} complex_t;


/* 128 point bit-reverse LUT */
static uint8_t 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 uint8_t 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};

static complex_t buf[128];

/* Twiddle factor LUT */
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];
static complex_t * w[7] = {w_1, w_2, w_4, w_8, w_16, w_32, w_64};

/* Twiddle factors for IMDCT */
static float xcos1[128];
static float xsin1[128];
static float xcos2[64];
static float xsin2[64];

/* Windowing function for Modified DCT - Thank you acroread */
float imdct_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 inline 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_do_512(float data[],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;

    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]) ; */ 
	buf[i].real =         (data[256-2*i-1] * xcos1[i])  -  (data[2*i]       * xsin1[i]);
	buf[i].imag = -1.0 * ((data[2*i]       * xcos1[i])  +  (data[256-2*i-1] * xsin1[i]));
    }

    //Bit reversed shuffling
    for(i=0; i<128; i++) {
	k = bit_reverse_512[i];
	if (k < i)
	    swap_cmplx(&buf[i],&buf[k]);
    }

    /* FFT Merge */
    for (m=0; m < 7; m++) {
	if(m)
	    two_m = (1 << m);
	else
	    two_m = 1;

	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 < 128; 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]);
    }
	
    data_ptr = data;
    delay_ptr = delay;
    window_ptr = imdct_window;

    /* Window and convert to real valued signal */
    for(i=0; i< 64; i++) { 
	*data_ptr++   = 2.0f * (-buf[64+i].imag   * *window_ptr++ + *delay_ptr++); 
	*data_ptr++   = 2.0f * ( buf[64-i-1].real * *window_ptr++ + *delay_ptr++); 
    }

    for(i=0; i< 64; i++) { 
	*data_ptr++  = 2.0f * (-buf[i].real       * *window_ptr++ + *delay_ptr++); 
	*data_ptr++  = 2.0f * ( buf[128-i-1].imag * *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].real   * *--window_ptr; 
	*delay_ptr++  =  buf[64-i-1].imag * *--window_ptr; 
    }

    for(i=0; i<64; i++) {
	*delay_ptr++  =  buf[i].imag       * *--window_ptr; 
	*delay_ptr++  = -buf[128-i-1].real * *--window_ptr; 
    }
}

void
imdct_do_256(float data[],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;

    float *data_ptr;
    float *delay_ptr;
    float *window_ptr;

    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<64; k++) { 
	/* X1[k] = X[2*k]  */
	/* X2[k] = X[2*k+1]     */

	p = 2 * (128-2*k-1);
	q = 2 * (2 * k);

	/* Z1[k] = (X1[128-2*k-1] + j * X1[2*k]) * (xcos2[k] + j * xsin2[k]); */ 
	buf_1[k].real =         data[p] * xcos2[k] - data[q] * xsin2[k];
	buf_1[k].imag = -1.0f * (data[q] * xcos2[k] + data[p] * xsin2[k]); 
	/* Z2[k] = (X2[128-2*k-1] + j * X2[2*k]) * (xcos2[k] + j * xsin2[k]); */ 
	buf_2[k].real =          data[p + 1] * xcos2[k] - data[q + 1] * xsin2[k];
	buf_2[k].imag = -1.0f * ( data[q + 1] * xcos2[k] + data[p + 1] * xsin2[k]); 
    }

    //IFFT Bit reversed shuffling
    for(i=0; i<64; 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));

	//FIXME
	if(m)
	    two_m = (1 << m);
	else
	    two_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 < 64; i++) {
	/* y1[n] = z1[n] * (xcos2[n] + j * xs in2[n]) ; */ 
	tmp_a_r =  buf_1[i].real;
	tmp_a_i = -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 = -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]);
    }
	
    data_ptr = data;
    delay_ptr = delay;
    window_ptr = imdct_window;

    /* Window and convert to real valued signal */
    for(i=0; i< 64; i++) { 
	*data_ptr++  = 2.0f * (-buf_1[i].imag      * *window_ptr++ + *delay_ptr++);
	*data_ptr++  = 2.0f * ( buf_1[64-i-1].real * *window_ptr++ + *delay_ptr++);
    }

    for(i=0; i< 64; i++) {
	*data_ptr++  = 2.0f * (-buf_1[i].real      * *window_ptr++ + *delay_ptr++);
	*data_ptr++  = 2.0f * ( buf_1[64-i-1].imag * *window_ptr++ + *delay_ptr++);
    }
	
    delay_ptr = delay;

    for(i=0; i< 64; i++) {
	*delay_ptr++ = -buf_2[i].real      * *--window_ptr;
	*delay_ptr++ =  buf_2[64-i-1].imag * *--window_ptr;
    }

    for(i=0; i< 64; i++) {
	*delay_ptr++ =  buf_2[i].imag      * *--window_ptr;
	*delay_ptr++ = -buf_2[64-i-1].real * *--window_ptr;
    }
}

void imdct_init (void)
{
#ifdef LIBAC3_MLIB
    void imdct_do_256_mlib(float data[],float delay[]);
    void imdct_do_512_mlib(float data[],float delay[]);

    imdct_512 = imdct_do_512_mlib;
    imdct_256 = imdct_do_256_mlib;
#else
    int i, j, k;

    /* Twiddle factors to turn IFFT into IMDCT */
    for (i = 0; i < 128; i++) {
	xcos1[i] = -cos ((M_PI / 2048) * (8 * i + 1));
	xsin1[i] = -sin ((M_PI / 2048) * (8 * i + 1));
    }

    /* More twiddle factors to turn IFFT into IMDCT */
    for (i = 0; i < 64; i++) {
	xcos2[i] = -cos ((M_PI / 1024) * (8 * i + 1));
	xsin2[i] = -sin ((M_PI / 1024) * (8 * i + 1));
    }

    for (i = 0; i < 7; i++) {
	j = 1 << i;
	for (k = 0; k < j; k++) {
	    w[i][k].real = cos (-M_PI * k / j);
	    w[i][k].imag = sin (-M_PI * k / j);
	}
    }
    imdct_512 = imdct_do_512;
    imdct_256 = imdct_do_256;
#endif
}