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layer2.c

/*
 * Mpeg Layer-2 audio decoder
 * --------------------------
 * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
 *
 */

#include <glib.h>
#include <math.h>

#include "beep/output.h"
#include "mpg123.h"
#include "l2tables.h"
#include "getbits.h"


static int grp_3tab[32 * 3] = { 0, };   /* used: 27 */
static int grp_5tab[128 * 3] = { 0, };  /* used: 125 */
static int grp_9tab[1024 * 3] = { 0, }; /* used: 729 */

real mpg123_muls[27][64];       /* also used by layer 1 */

/* Used by the getbits macros */
static unsigned long rval;

void
mpg123_init_layer2(gboolean mmx)
{
    static double mulmul[27] = {
        0.0, -2.0 / 3.0, 2.0 / 3.0, 2.0 / 7.0, 2.0 / 15.0,
        2.0 / 31.0, 2.0 / 63.0, 2.0 / 127.0, 2.0 / 255.0,
        2.0 / 511.0, 2.0 / 1023.0, 2.0 / 2047.0, 2.0 / 4095.0,
        2.0 / 8191.0, 2.0 / 16383.0, 2.0 / 32767.0, 2.0 / 65535.0,
        -4.0 / 5.0, -2.0 / 5.0, 2.0 / 5.0, 4.0 / 5.0, -8.0 / 9.0,
        -4.0 / 9.0, -2.0 / 9.0, 2.0 / 9.0, 4.0 / 9.0, 8.0 / 9.0
    };
    static int base[3][9] = {
        {1, 0, 2,},
        {17, 18, 0, 19, 20,},
        {21, 1, 22, 23, 0, 24, 25, 2, 26}
    };
    int i, j, k, l, len;
    real *table;
    static int tablen[3] = { 3, 5, 9 };
    static int *itable, *tables[3] = { grp_3tab, grp_5tab, grp_9tab };

    for (i = 0; i < 3; i++) {
        itable = tables[i];
        len = tablen[i];
        for (j = 0; j < len; j++)
            for (k = 0; k < len; k++)
                for (l = 0; l < len; l++) {
                    *itable++ = base[i][l];
                    *itable++ = base[i][k];
                    *itable++ = base[i][j];
                }
    }

    for (k = 0; k < 27; k++) {
        double m = mulmul[k];
        table = mpg123_muls[k];
#ifdef USE_SIMD
        if (mmx)
            for (j = 3, i = 0; i < 63; i++, j--)
                *table++ = 16384 * m * pow(2.0, (double) j / 3.0);
        else
#endif
            for (j = 3, i = 0; i < 63; i++, j--)
                *table++ = m * pow(2.0, (double) j / 3.0);
        *table++ = 0.0;
    }
}

void
II_step_one(unsigned int *bit_alloc, int *scale, struct frame *fr)
{
    int stereo = fr->stereo - 1;
    int sblimit = fr->II_sblimit;
    int jsbound = fr->jsbound;
    int sblimit2 = fr->II_sblimit << stereo;
    struct al_table *alloc1 = fr->alloc;
    int i;
    static unsigned int scfsi_buf[64];
    unsigned int *scfsi, *bita;
    int sc, step;

    bita = bit_alloc;
    if (stereo) {
        for (i = jsbound; i > 0; i--, alloc1 += (1 << step)) {
            *bita++ = (char) mpg123_getbits(step = alloc1->bits);
            *bita++ = (char) mpg123_getbits(step);
        }
        for (i = sblimit - jsbound; i > 0; i--, alloc1 += (1 << step)) {
            bita[0] = (char) mpg123_getbits(step = alloc1->bits);
            bita[1] = bita[0];
            bita += 2;
        }
        bita = bit_alloc;
        scfsi = scfsi_buf;
        for (i = sblimit2; i; i--)
            if (*bita++)
                *scfsi++ = (char) mpg123_getbits_fast(2);
    }
    else
        /* mono */
    {
        for (i = sblimit; i; i--, alloc1 += (1 << step))
            *bita++ = (char) mpg123_getbits(step = alloc1->bits);
        bita = bit_alloc;
        scfsi = scfsi_buf;
        for (i = sblimit; i; i--)
            if (*bita++)
                *scfsi++ = (char) mpg123_getbits_fast(2);
    }

    bita = bit_alloc;
    scfsi = scfsi_buf;
    for (i = sblimit2; i; i--)
        if (*bita++)
            switch (*scfsi++) {
            case 0:
                *scale++ = mpg123_getbits_fast(6);
                *scale++ = mpg123_getbits_fast(6);
                *scale++ = mpg123_getbits_fast(6);
                break;
            case 1:
                *scale++ = sc = mpg123_getbits_fast(6);
                *scale++ = sc;
                *scale++ = mpg123_getbits_fast(6);
                break;
            case 2:
                *scale++ = sc = mpg123_getbits_fast(6);
                *scale++ = sc;
                *scale++ = sc;
                break;
            default:           /* case 3 */
                *scale++ = mpg123_getbits_fast(6);
                *scale++ = sc = mpg123_getbits_fast(6);
                *scale++ = sc;
                break;
            }

}

void
II_step_two(unsigned int *bit_alloc, real fraction[2][4][SBLIMIT],
            int *scale, struct frame *fr, int x1)
{
    int i, j, k, ba;
    int stereo = fr->stereo;
    int sblimit = fr->II_sblimit;
    int jsbound = fr->jsbound;
    struct al_table *alloc2, *alloc1 = fr->alloc;
    unsigned int *bita = bit_alloc;
    int d1, step;

    for (i = 0; i < jsbound; i++, alloc1 += (1 << step)) {
        step = alloc1->bits;
        for (j = 0; j < stereo; j++) {
            if ((ba = *bita++)) {
                k = (alloc2 = alloc1 + ba)->bits;
                if ((d1 = alloc2->d) < 0) {
                    real cm = mpg123_muls[k][scale[x1]];

                    fraction[j][0][i] =
                        ((real) ((int) mpg123_getbits(k) + d1)) * cm;
                    fraction[j][1][i] =
                        ((real) ((int) mpg123_getbits(k) + d1)) * cm;
                    fraction[j][2][i] =
                        ((real) ((int) mpg123_getbits(k) + d1)) * cm;
                }
                else {
                    static int *table[] =
                        { 0, 0, 0, grp_3tab, 0, grp_5tab, 0, 0, 0,
                        grp_9tab
                    };
                    unsigned int idx, *tab, m = scale[x1];

                    idx = (unsigned int) mpg123_getbits(k);
                    tab = (unsigned int *) (table[d1] + idx + idx + idx);
                    fraction[j][0][i] = mpg123_muls[*tab++][m];
                    fraction[j][1][i] = mpg123_muls[*tab++][m];
                    fraction[j][2][i] = mpg123_muls[*tab][m];
                }
                scale += 3;
            }
            else
                fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] =
                    0.0;
        }
    }

    for (i = jsbound; i < sblimit; i++, alloc1 += (1 << step)) {
        step = alloc1->bits;
        bita++;                 /* channel 1 and channel 2 bitalloc are the same */
        if ((ba = *bita++)) {
            k = (alloc2 = alloc1 + ba)->bits;
            if ((d1 = alloc2->d) < 0) {
                real cm;

                cm = mpg123_muls[k][scale[x1 + 3]];
                fraction[1][0][i] = (fraction[0][0][i] =
                                     (real) ((int) mpg123_getbits(k) +
                                             d1)) * cm;
                fraction[1][1][i] = (fraction[0][1][i] =
                                     (real) ((int) mpg123_getbits(k) +
                                             d1)) * cm;
                fraction[1][2][i] = (fraction[0][2][i] =
                                     (real) ((int) mpg123_getbits(k) +
                                             d1)) * cm;
                cm = mpg123_muls[k][scale[x1]];
                fraction[0][0][i] *= cm;
                fraction[0][1][i] *= cm;
                fraction[0][2][i] *= cm;
            }
            else {
                static int *table[] =
                    { 0, 0, 0, grp_3tab, 0, grp_5tab, 0, 0, 0, grp_9tab };
                unsigned int idx, *tab, m1, m2;

                m1 = scale[x1];
                m2 = scale[x1 + 3];
                idx = (unsigned int) mpg123_getbits(k);
                tab = (unsigned int *) (table[d1] + idx + idx + idx);
                fraction[0][0][i] = mpg123_muls[*tab][m1];
                fraction[1][0][i] = mpg123_muls[*tab++][m2];
                fraction[0][1][i] = mpg123_muls[*tab][m1];
                fraction[1][1][i] = mpg123_muls[*tab++][m2];
                fraction[0][2][i] = mpg123_muls[*tab][m1];
                fraction[1][2][i] = mpg123_muls[*tab][m2];
            }
            scale += 6;
        }
        else {
            fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] =
                fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] =
                0.0;
        }
/*
   should we use individual scalefac for channel 2 or
   is the current way the right one , where we just copy channel 1 to
   channel 2 ??
   The current 'strange' thing is, that we throw away the scalefac
   values for the second channel ...!!
   -> changed .. now we use the scalefac values of channel one !!
 */
    }

    if (sblimit > (fr->down_sample_sblimit))
        sblimit = fr->down_sample_sblimit;

    for (i = sblimit; i < SBLIMIT; i++)
        for (j = 0; j < stereo; j++)
            fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;

}

static void
II_select_table(struct frame *fr)
{
    static int translate[3][2][16] = {
        {{0, 2, 2, 2, 2, 2, 2, 0, 0, 0, 1, 1, 1, 1, 1, 0},
         {0, 2, 2, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0}},
        {{0, 2, 2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0},
         {0, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}},
        {{0, 3, 3, 3, 3, 3, 3, 0, 0, 0, 1, 1, 1, 1, 1, 0},
         {0, 3, 3, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0}}
    };

    int table, sblim;
    static struct al_table *tables[5] =
        { alloc_0, alloc_1, alloc_2, alloc_3, alloc_4 };
    static int sblims[5] = { 27, 30, 8, 12, 30 };

    if (fr->lsf)
        table = 4;
    else
        table =
            translate[fr->sampling_frequency][2 -
                                              fr->stereo][fr->bitrate_index];
    sblim = sblims[table];

    fr->alloc = tables[table];
    fr->II_sblimit = sblim;
}


int
mpg123_do_layer2(struct frame *fr)
{
    int i, j;
    int stereo = fr->stereo;
    real fraction[2][4][SBLIMIT];   /* pick_table clears unused subbands */
    unsigned int bit_alloc[64];
    int scale[192];
    int single = fr->single;

    II_select_table(fr);
    fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ?
        (fr->mode_ext << 2) + 4 : fr->II_sblimit;
    if (fr->jsbound > fr->II_sblimit)
        fr->jsbound = fr->II_sblimit;

    if (stereo == 1 || single == 3)
        single = 0;

    II_step_one(bit_alloc, scale, fr);

    for (i = 0; i < SCALE_BLOCK; i++) {
        II_step_two(bit_alloc, fraction, scale, fr, i >> 2);
        for (j = 0; j < 3; j++) {
            if (single >= 0) {
                (fr->synth_mono) (fraction[single][j], mpg123_pcm_sample,
                                  &mpg123_pcm_point);
            }
            else {
                int p1 = mpg123_pcm_point;

                (fr->synth) (fraction[0][j], 0, mpg123_pcm_sample, &p1);
                (fr->synth) (fraction[1][j], 1, mpg123_pcm_sample,
                             &mpg123_pcm_point);
            }

            /*    if(mpg123_pcm_point >= audiobufsize)
               audio_flush(outmode,ai); */
        }
    }
    if (mpg123_info->output_audio && mpg123_info->jump_to_time == -1) {
        produce_audio(mpg123_ip.output->written_time(),
                      mpg123_cfg.resolution ==
                      16 ? FMT_S16_NE : FMT_U8,
                      mpg123_cfg.channels ==
                      2 ? fr->stereo : 1, mpg123_pcm_point,
                      mpg123_pcm_sample, &mpg123_info->going);
    }

    mpg123_pcm_point = 0;

    return 1;
}

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