PeerStreamer

/*

 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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;

    }

}