g727.c

Reference Implementation of G.711 standard and other voice codecs

    g727_asc_transit(&st->asc, ic, y, tr, tdp, cbits);
    g727_aprsc_transit(&st->aprsc, dqfb, tr, srfb, a2p, pk0, sigpk);
    g727_ttd_transit(&st->ttd, tr, tdp);

    return sd;
}
/* ..................... End of G727_decode_sample() ..................... */




/* ********************************************************************** *
 * ******** PRIVATE FUNCTIONS - DO NOT GO BEYOND THIS POINT ... ********* *
 * ********************************************************************** */

/*---------- Input PCM format conversion and difference ----------*/
/*---------- signal computation (G.727 6.2.1) --------------------*/

Int16
g727_get_d(Int8 s, Int16 se, short law)
{
    Int8 sp = (law == 1) ? (0xd5 ^ s) : (0xff ^ s);

    return g727_subta(g727_expand(sp, law), se);
}


Int16
g727_expand(Int8 sp, short law)
{
    Int16 ss = 0x21 | ((sp & 0xf) << 1);
    Int8 sss;
    Int16 ssq;
    Int16 sl;

    if (law == 1) {
        if ((sp & 0x70) == 0)
            ss ^= 0x20;
        else
            ss <<= ((sp & 0x70) >> 4) - 1;

        ss |= (sp & 0x80) << 5;
    }
    else if (law == 0) {
        ss <<= (sp & 0x70) >> 4;
        ss -= 33;
        ss |= (sp & 0x80) << 6;
    }
    else
        assert(0);

    if (law == 0) {
        sss = ss >> 13;
        ssq = ss & 8191;
    } else {
        Int16 ssm;

        sss = ss >> 12;
        ssm = ss & 4095;
        ssq = ssm << 1;
    }

    if (sss == 0)
        sl = ssq;
    else if (sss == 1)
        sl = (16384 - ssq) & 16383;
    else
        assert(0);

    return sl;
}


Int16
g727_subta(Int16 sl, Int16 se)
{
    Int8 sls = sl >> 13;
    Int16 sli;
    Int8 ses;
    Int16 sei;

    if (sls == 0)
        sli = sl;
    else if (sls == 1)
        sli = 49152 + sl;
    else
        assert(0);

    ses = se >> 14;

    if (ses == 0)
        sei = se;
    else if (ses == 1)
        sei = 32768 + se;
    else
        assert(0);

    return (sli + 65536UL - sei) & 65535;
}


/*---------- Adaptive quantizer (G.727 6.2.2) ----------*/

Int8
g727_get_in(Int16 d, Int16 y, short rate)
{
    Int16 dl;
    Int8 ds;

    g727_log(&dl, &ds, d);

    return g727_quan(g727_subtb(dl, y), ds, rate);
}


void
g727_log(Int16 *dl, Int8 *ds, Int16 d)
{
    Int16 dqm;
    Int8 exp;
    Int8 mant;

    *ds = d >> 15;

    if (*ds == 0)
        dqm = d;
    else if (*ds == 1)
        dqm = (65536 - d) & 32767;
    else
        assert(0);

    if (16384 <= dqm)
        exp = 14;
    else if (8192 <= dqm)
        exp = 13;
    else if (4096 <= dqm)
        exp = 12;
    else if (2048 <= dqm)
        exp = 11;
    else if (1024 <= dqm)
        exp = 10;
    else if (512 <= dqm)
        exp = 9;
    else if (256 <= dqm)
        exp = 8;
    else if (128 <= dqm)
        exp = 7;
    else if (64 <= dqm)
        exp = 6;
    else if (32 <= dqm)
        exp = 5;
    else if (16 <= dqm)
        exp = 4;
    else if (8 <= dqm)
        exp = 3;
    else if (4 <= dqm)
        exp = 2;
    else if (2 <= dqm)
        exp = 1;
    else
        exp = 0;

    mant = (((Int32)dqm << 7) >> exp) & 127;

    *dl = ((Int16)exp << 7) + mant;
}


Int8
g727_quan(Int16 dln, Int8 ds, short rate)
{
    Int8 in;

    switch (rate) {
        case 5:
            if (4096 <= dln)
                assert(0);
            else if (4089 <= dln)
                in = 2;
            else if (3961 <= dln)
                in = 1;
            else if (2048 <= dln)
                in = 0;
            else if (439 <= dln)
                in = 15;
            else if (405 <= dln)
                in = 14;
            else if (380 <= dln)
                in = 13;
            else if (356 <= dln)
                in = 12;
            else if (333 <= dln)
                in = 11;
            else if (310 <= dln)
                in = 10;
            else if (286 <= dln)
                in = 9;
            else if (261 <= dln)
                in = 8;
            else if (233 <= dln)
                in = 7;
            else if (202 <= dln)
                in = 6;
            else if (166 <= dln)
                in = 5;
            else if (123 <= dln)
                in = 4;
            else if (69 <= dln)
                in = 3;
            else
                in = 2;

            in = (ds == 1) ? ((~in) & 0x1f) : in;
            break;

        case 4:
            if (4096 <= dln)
                assert(0);
            else if (4089 <= dln)
                in = 1;
            else if (2048 <= dln)
                in = 0;
            else if (405 <= dln)
                in = 7;
            else if (356 <= dln)
                in = 6;
            else if (310 <= dln)
                in = 5;
            else if (261 <= dln)
                in = 4;
            else if (202 <= dln)
                in = 3;
            else if (123 <= dln)
                in = 2;
            else
                in = 1;

            in = (ds == 1) ? ((~in) & 0xf) : in;
            break;

        case 3:
            if (4096 <= dln)
                assert(0);
            else if (2048 <= dln)
                in = 0;
            else if (356 <= dln)
                in = 3;
            else if (261 <= dln)
                in = 2;
            else if (123 <= dln)
                in = 1;
            else
                in = 0;

            in = (ds == 1) ? ((~in) & 0x7) : in;
            break;

        case 2:
            if (4096 <= dln)
                assert(0);
            else if (2048 <= dln)
                in = 0;
            else if (261 <= dln)
                in = 1;
            else
                in = 0;

            in = (ds == 1) ? ((~in) & 0x3) : in;
            break;

        default:
            assert(0);
    }

    return in;
}


Int16
g727_subtb(Int16 dl, Int16 y)
{
    return (dl + 4096 - (y >> 2)) & 4095;
}


/*---------- Bit masking (G.727 6.2.3) ----------*/

Int8
g727_get_ic(Int8 in, short enh)
{
    return in >> enh;
}


/*---------- Inverse Adaptive Quantizer (G.727 6.2.4) ----------*/

Int16
g727_get_dq(Int16 y, Int8 in, short rate)
{
    Int16 dqln;
    Int8 dqs;

    g727_reconst(&dqln, &dqs, in, rate);

    return g727_antilog(g727_adda(dqln, y), dqs);
}


Int16
g727_antilog(Int16 dql, Int8 dqs)
{
    Int8 ds = dql >> 11;
    Int8 dex = (dql >> 7) & 15;
    Int8 dmn = dql & 127;

    Int8 dqt = (1 << 7) + dmn;
    Int16 dqmag;

    if (ds == 0)
        dqmag = (dqt << 7) >> (14 - dex);
    else if (ds == 1)
        dqmag = 0;
    else
        assert(0);

    return (dqs << 14) + dqmag;
}


Int16
g727_adda(Int16 dqln, Int16 y)
{
    return (dqln + (y >> 2)) & 4095;
}


void
g727_reconst(Int16 *dqln, Int8 *dqs, Int8 in, short rate)
{
    switch (rate) {
        case 5:
            *dqs = in >> 4;
            *dqln = g727_dqlnTable40[in];
            break;

        case 4:
            *dqs = in >> 3;
            *dqln = g727_dqlnTable32[in];
            break;

        case 3:
            *dqs = in >> 2;
            *dqln = g727_dqlnTable24[in];
            break;

        case 2:
            *dqs = in >> 1;
            *dqln = g727_dqlnTable16[in];
            break;

        default:
            assert(0);
    }
}


/*---------- Quantizer Scale Factor Adaptation (G.727 6.2.5) ----------*/

void
g727_qsfa_reset(g727_qsfa_state *st)
{
    st->yl = 34816;
    st->yu = 544;
}


Int16
g727_get_y(g727_qsfa_state *st, Int8 al)
{
    return g727_mix(st, al);
}


Int32
g727_get_yl(g727_qsfa_state *st)
{
    return st->yl;
}


void
g727_qsfa_transit(g727_qsfa_state *st, Int8 in, Int16 y, short rate)
{
    Int16 yup = g727_limb(g727_filtd(g727_functw(in, rate), y));
    Int32 ylp = g727_filte(st, yup);

    st->yu = yup;
    st->yl = ylp;
}


Int16
g727_filtd(Int16 wi, Int16 y)
{
    Int32 dif = (((Int32)wi << 5) + 131072 - y) & 131071;
    Int8 difs = dif >> 16;
    Int16 difsx;

    if (difs == 0)
        difsx = dif >> 5;
    else if (difs == 1)
        difsx = (dif >> 5) + 4096;
    else
        assert(0);

    return (y + difsx) & 8191;
}


Int32
g727_filte(g727_qsfa_state *st, Int16 yup)
{
    Int16 dif = (yup + ((1048576 - st->yl) >> 6)) & 16383;
    Int8 difs = dif >> 13;
    Int32 difsx;

    if (difs == 0)
        difsx = dif;
    else if (difs == 1)
        difsx = dif + 507904;
    else
        assert(0);

    return (st->yl + difsx) & 524287;
}


Int16
g727_functw(Int8 in, short rate)
{
    Int8 is;
    Int8 im;
    Int16 wi;

    switch (rate) {
        case 4:
            is = in >> 3;

            if (is == 0)
                im = in & 7;
            else if (is == 1)
                im = (15 - in) & 7;
            else
                assert(0);

            wi = g727_wiTable32[im];
            break;

        case 3:
            is = in >> 2;

            if (is == 0)
                im = in & 3;
            else if (is == 1)
                im = (7 - in) & 3;
            else
                assert(0);

            wi = g727_wiTable24[im];
            break;

        case 2:
            is = in >> 1;

            if (is == 0)
                im = in & 1;
            else if (is == 1)
                im = (3 - in) & 1;
            else
                assert(0);

            wi = g727_wiTable16[im];
            break;

        default:
            assert(0);
    }

    return wi;
}


Int16
g727_limb(Int16 yut)
{
    Int8 geul = ((yut + 11264) & 16383) >> 13;
    Int8 gell = ((yut + 15840) & 16383) >> 13;
    Int16 yup;

    if (gell == 1)
        yup = 544;
    else if (geul == 0)
        yup = 5120;
    else
        yup = yut;

    return yup;
}


Int16
g727_mix(g727_qsfa_state *st, Int8 al)
{
    Int16 dif = (st->yu + 16384 - (st->yl >> 6)) & 16383;
    Int8 difs = dif >> 13;
    Int16 difm;
    Int16 prodm;
    Int16 prod;

    if (difs == 0)
        difm = dif;
    else if (difs == 1)
        difm = (16384 - dif) & 8191;