Let's also include aclocal.m4

[asterisk-bristuff.git] / codecs / codec_g726.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 * Kevin P. Fleming <kpfleming@digium.com>
 *
 * Based on frompcm.c and topcm.c from the Emiliano MIPL browser/
 * interpreter.  See http://www.bsdtelephony.com.mx
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief codec_g726.c - translate between signed linear and ITU G.726-32kbps (both RFC3551 and AAL2 codeword packing)
 *
 * \ingroup codecs
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "asterisk/lock.h"
#include "asterisk/logger.h"
#include "asterisk/linkedlists.h"
#include "asterisk/module.h"
#include "asterisk/config.h"
#include "asterisk/options.h"
#include "asterisk/translate.h"
#include "asterisk/channel.h"
#include "asterisk/utils.h"

#define WANT_ASM
#include "log2comp.h"

/* define NOT_BLI to use a faster but not bit-level identical version */
/* #define NOT_BLI */

#if defined(NOT_BLI)
#       if defined(_MSC_VER)
typedef __int64 sint64;
#       elif defined(__GNUC__)
typedef long long sint64;
#       else
#               error 64-bit integer type is not defined for your compiler/platform
#       endif
#endif

#define BUFFER_SAMPLES   8096   /* size for the translation buffers */
#define BUF_SHIFT       5

/* Sample frame data */

#include "slin_g726_ex.h"
#include "g726_slin_ex.h"

/*
 * The following is the definition of the state structure
 * used by the G.726 encoder and decoder to preserve their internal
 * state between successive calls.  The meanings of the majority
 * of the state structure fields are explained in detail in the
 * CCITT Recommendation G.721.  The field names are essentially identical
 * to variable names in the bit level description of the coding algorithm
 * included in this Recommendation.
 */
struct g726_state {
        long yl;        /* Locked or steady state step size multiplier. */
        int yu;         /* Unlocked or non-steady state step size multiplier. */
        int dms;        /* Short term energy estimate. */
        int dml;        /* Long term energy estimate. */
        int ap;         /* Linear weighting coefficient of 'yl' and 'yu'. */
        int a[2];       /* Coefficients of pole portion of prediction filter.
                         * stored as fixed-point 1==2^14 */
        int b[6];       /* Coefficients of zero portion of prediction filter.
                         * stored as fixed-point 1==2^14 */
        int pk[2];      /* Signs of previous two samples of a partially
                         * reconstructed signal. */
        int dq[6];      /* Previous 6 samples of the quantized difference signal
                         * stored as fixed point 1==2^12,
                         * or in internal floating point format */
        int sr[2];      /* Previous 2 samples of the quantized difference signal
                         * stored as fixed point 1==2^12,
                         * or in internal floating point format */
        int td;         /* delayed tone detect, new in 1988 version */
};

static int qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
/*
 * Maps G.721 code word to reconstructed scale factor normalized log
 * magnitude values.
 */
static int _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
                                425, 373, 323, 273, 213, 135, 4, -2048};

/* Maps G.721 code word to log of scale factor multiplier. */
static int _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
                                1122, 355, 198, 112, 64, 41, 18, -12};
/*
 * Maps G.721 code words to a set of values whose long and short
 * term averages are computed and then compared to give an indication
 * how stationary (steady state) the signal is.
 */
static int _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
                                0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};


/*
 * g72x_init_state()
 *
 * This routine initializes and/or resets the g726_state structure
 * pointed to by 'state_ptr'.
 * All the initial state values are specified in the CCITT G.721 document.
 */
static void g726_init_state(struct g726_state *state_ptr)
{
        int             cnta;

        state_ptr->yl = 34816;
        state_ptr->yu = 544;
        state_ptr->dms = 0;
        state_ptr->dml = 0;
        state_ptr->ap = 0;
        for (cnta = 0; cnta < 2; cnta++) {
                state_ptr->a[cnta] = 0;
                state_ptr->pk[cnta] = 0;
#ifdef NOT_BLI
                state_ptr->sr[cnta] = 1;
#else
                state_ptr->sr[cnta] = 32;
#endif
        }
        for (cnta = 0; cnta < 6; cnta++) {
                state_ptr->b[cnta] = 0;
#ifdef NOT_BLI
                state_ptr->dq[cnta] = 1;
#else
                state_ptr->dq[cnta] = 32;
#endif
        }
        state_ptr->td = 0;
}

/*
 * quan()
 *
 * quantizes the input val against the table of integers.
 * It returns i if table[i - 1] <= val < table[i].
 *
 * Using linear search for simple coding.
 */
static int quan(int val, int *table, int size)
{
        int             i;

        for (i = 0; i < size && val >= *table; ++i, ++table)
                ;
        return (i);
}

#ifdef NOT_BLI /* faster non-identical version */

/*
 * predictor_zero()
 *
 * computes the estimated signal from 6-zero predictor.
 *
 */
static int predictor_zero(struct g726_state *state_ptr)
{       /* divide by 2 is necessary here to handle negative numbers correctly */
        int i;
        sint64 sezi;
        for (sezi = 0, i = 0; i < 6; i++)                       /* ACCUM */
                sezi += (sint64)state_ptr->b[i] * state_ptr->dq[i];
        return (int)(sezi >> 13) / 2 /* 2^14 */;
}

/*
 * predictor_pole()
 *
 * computes the estimated signal from 2-pole predictor.
 *
 */
static int predictor_pole(struct g726_state *state_ptr)
{       /* divide by 2 is necessary here to handle negative numbers correctly */
        return (int)(((sint64)state_ptr->a[1] * state_ptr->sr[1] +
                      (sint64)state_ptr->a[0] * state_ptr->sr[0]) >> 13) / 2 /* 2^14 */;
}

#else /* NOT_BLI - identical version */
/*
 * fmult()
 *
 * returns the integer product of the fixed-point number "an" (1==2^12) and
 * "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
 */
static int fmult(int an, int srn)
{
        int             anmag, anexp, anmant;
        int             wanexp, wanmant;
        int             retval;

        anmag = (an > 0) ? an : ((-an) & 0x1FFF);
        anexp = ilog2(anmag) - 5;
        anmant = (anmag == 0) ? 32 :
            (anexp >= 0) ? anmag >> anexp : anmag << -anexp;
        wanexp = anexp + ((srn >> 6) & 0xF) - 13;

        wanmant = (anmant * (srn & 077) + 0x30) >> 4;
        retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) :
            (wanmant >> -wanexp);

        return (((an ^ srn) < 0) ? -retval : retval);
}

static int predictor_zero(struct g726_state *state_ptr)
{
        int             i;
        int             sezi;
        for (sezi = 0, i = 0; i < 6; i++)                       /* ACCUM */
                sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
        return sezi;
}

static int predictor_pole(struct g726_state *state_ptr)
{
        return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
                        fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
}

#endif /* NOT_BLI */

/*
 * step_size()
 *
 * computes the quantization step size of the adaptive quantizer.
 *
 */
static int step_size(struct g726_state *state_ptr)
{
        int             y;
        int             dif;
        int             al;

        if (state_ptr->ap >= 256)
                return (state_ptr->yu);
        else {
                y = state_ptr->yl >> 6;
                dif = state_ptr->yu - y;
                al = state_ptr->ap >> 2;
                if (dif > 0)
                        y += (dif * al) >> 6;
                else if (dif < 0)
                        y += (dif * al + 0x3F) >> 6;
                return (y);
        }
}

/*
 * quantize()
 *
 * Given a raw sample, 'd', of the difference signal and a
 * quantization step size scale factor, 'y', this routine returns the
 * ADPCM codeword to which that sample gets quantized.  The step
 * size scale factor division operation is done in the log base 2 domain
 * as a subtraction.
 */
static int quantize(
        int             d,      /* Raw difference signal sample */
        int             y,      /* Step size multiplier */
        int             *table, /* quantization table */
        int             size)   /* table size of integers */
{
        int             dqm;    /* Magnitude of 'd' */
        int             exp;    /* Integer part of base 2 log of 'd' */
        int             mant;   /* Fractional part of base 2 log */
        int             dl;             /* Log of magnitude of 'd' */
        int             dln;    /* Step size scale factor normalized log */
        int             i;

        /*
         * LOG
         *
         * Compute base 2 log of 'd', and store in 'dl'.
         */
        dqm = abs(d);
        exp = ilog2(dqm);
        if (exp < 0)
                exp = 0;
        mant = ((dqm << 7) >> exp) & 0x7F;      /* Fractional portion. */
        dl = (exp << 7) | mant;

        /*
         * SUBTB
         *
         * "Divide" by step size multiplier.
         */
        dln = dl - (y >> 2);

        /*
         * QUAN
         *
         * Obtain codword i for 'd'.
         */
        i = quan(dln, table, size);
        if (d < 0)                      /* take 1's complement of i */
                return ((size << 1) + 1 - i);
        else if (i == 0)                /* take 1's complement of 0 */
                return ((size << 1) + 1); /* new in 1988 */
        else
                return (i);
}

/*
 * reconstruct()
 *
 * Returns reconstructed difference signal 'dq' obtained from
 * codeword 'i' and quantization step size scale factor 'y'.
 * Multiplication is performed in log base 2 domain as addition.
 */
static int reconstruct(
        int             sign,   /* 0 for non-negative value */
        int             dqln,   /* G.72x codeword */
        int             y)      /* Step size multiplier */
{
        int             dql;    /* Log of 'dq' magnitude */
        int             dex;    /* Integer part of log */
        int             dqt;
        int             dq;     /* Reconstructed difference signal sample */

        dql = dqln + (y >> 2);  /* ADDA */

        if (dql < 0) {
#ifdef NOT_BLI
                return (sign) ? -1 : 1;
#else
                return (sign) ? -0x8000 : 0;
#endif
        } else {                /* ANTILOG */
                dex = (dql >> 7) & 15;
                dqt = 128 + (dql & 127);
#ifdef NOT_BLI
                dq = ((dqt << 19) >> (14 - dex));
                return (sign) ? -dq : dq;
#else
                dq = (dqt << 7) >> (14 - dex);
                return (sign) ? (dq - 0x8000) : dq;
#endif
        }
}

/*
 * update()
 *
 * updates the state variables for each output code
 */
static void update(
        int             code_size,      /* distinguish 723_40 with others */
        int             y,              /* quantizer step size */
        int             wi,             /* scale factor multiplier */
        int             fi,             /* for long/short term energies */
        int             dq,             /* quantized prediction difference */
        int             sr,             /* reconstructed signal */
        int             dqsez,          /* difference from 2-pole predictor */
        struct g726_state *state_ptr)   /* coder state pointer */
{
        int             cnt;
        int             mag;            /* Adaptive predictor, FLOAT A */
#ifndef NOT_BLI
        int             exp;
#endif
        int             a2p=0;          /* LIMC */
        int             a1ul;           /* UPA1 */
        int             pks1;           /* UPA2 */
        int             fa1;
        int             tr;                     /* tone/transition detector */
        int             ylint, thr2, dqthr;
        int             ylfrac, thr1;
        int             pk0;

        pk0 = (dqsez < 0) ? 1 : 0;      /* needed in updating predictor poles */

#ifdef NOT_BLI
        mag = abs(dq / 0x1000); /* prediction difference magnitude */
#else
        mag = dq & 0x7FFF;              /* prediction difference magnitude */
#endif
        /* TRANS */
        ylint = state_ptr->yl >> 15;    /* exponent part of yl */
        ylfrac = (state_ptr->yl >> 10) & 0x1F;  /* fractional part of yl */
        thr1 = (32 + ylfrac) << ylint;          /* threshold */
        thr2 = (ylint > 9) ? 31 << 10 : thr1;   /* limit thr2 to 31 << 10 */
        dqthr = (thr2 + (thr2 >> 1)) >> 1;      /* dqthr = 0.75 * thr2 */
        if (state_ptr->td == 0)         /* signal supposed voice */
                tr = 0;
        else if (mag <= dqthr)          /* supposed data, but small mag */
                tr = 0;                 /* treated as voice */
        else                            /* signal is data (modem) */
                tr = 1;

        /*
         * Quantizer scale factor adaptation.
         */

        /* FUNCTW & FILTD & DELAY */
        /* update non-steady state step size multiplier */
        state_ptr->yu = y + ((wi - y) >> 5);

        /* LIMB */
        if (state_ptr->yu < 544)        /* 544 <= yu <= 5120 */
                state_ptr->yu = 544;
        else if (state_ptr->yu > 5120)
                state_ptr->yu = 5120;

        /* FILTE & DELAY */
        /* update steady state step size multiplier */
        state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);

        /*
         * Adaptive predictor coefficients.
         */
        if (tr == 1) {                  /* reset a's and b's for modem signal */
                state_ptr->a[0] = 0;
                state_ptr->a[1] = 0;
                state_ptr->b[0] = 0;
                state_ptr->b[1] = 0;
                state_ptr->b[2] = 0;
                state_ptr->b[3] = 0;
                state_ptr->b[4] = 0;
                state_ptr->b[5] = 0;
        } else {                        /* update a's and b's */
                pks1 = pk0 ^ state_ptr->pk[0];          /* UPA2 */

                /* update predictor pole a[1] */
                a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
                if (dqsez != 0) {
                        fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
                        if (fa1 < -8191)        /* a2p = function of fa1 */
                                a2p -= 0x100;
                        else if (fa1 > 8191)
                                a2p += 0xFF;
                        else
                                a2p += fa1 >> 5;

                        if (pk0 ^ state_ptr->pk[1])
                                /* LIMC */
                                if (a2p <= -12160)
                                        a2p = -12288;
                                else if (a2p >= 12416)
                                        a2p = 12288;
                                else
                                        a2p -= 0x80;
                        else if (a2p <= -12416)
                                a2p = -12288;
                        else if (a2p >= 12160)
                                a2p = 12288;
                        else
                                a2p += 0x80;
                }

                /* TRIGB & DELAY */
                state_ptr->a[1] = a2p;

                /* UPA1 */
                /* update predictor pole a[0] */
                state_ptr->a[0] -= state_ptr->a[0] >> 8;
                if (dqsez != 0) {
                        if (pks1 == 0)
                                state_ptr->a[0] += 192;
                        else
                                state_ptr->a[0] -= 192;
                }
                /* LIMD */
                a1ul = 15360 - a2p;
                if (state_ptr->a[0] < -a1ul)
                        state_ptr->a[0] = -a1ul;
                else if (state_ptr->a[0] > a1ul)
                        state_ptr->a[0] = a1ul;

                /* UPB : update predictor zeros b[6] */
                for (cnt = 0; cnt < 6; cnt++) {
                        if (code_size == 5)             /* for 40Kbps G.723 */
                                state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
                        else                    /* for G.721 and 24Kbps G.723 */
                                state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
                        if (mag)
                        {       /* XOR */
                                if ((dq ^ state_ptr->dq[cnt]) >= 0)
                                        state_ptr->b[cnt] += 128;
                                else
                                        state_ptr->b[cnt] -= 128;
                        }
                }
        }

        for (cnt = 5; cnt > 0; cnt--)
                state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
#ifdef NOT_BLI
        state_ptr->dq[0] = dq;
#else
        /* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
        if (mag == 0) {
                state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0x20 - 0x400;
        } else {
                exp = ilog2(mag) + 1;
                state_ptr->dq[0] = (dq >= 0) ?
                    (exp << 6) + ((mag << 6) >> exp) :
                    (exp << 6) + ((mag << 6) >> exp) - 0x400;
        }
#endif

        state_ptr->sr[1] = state_ptr->sr[0];
#ifdef NOT_BLI
        state_ptr->sr[0] = sr;
#else
        /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
        if (sr == 0) {
                state_ptr->sr[0] = 0x20;
        } else if (sr > 0) {
                exp = ilog2(sr) + 1;
                state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
        } else if (sr > -0x8000) {
                mag = -sr;
                exp = ilog2(mag) + 1;
                state_ptr->sr[0] =  (exp << 6) + ((mag << 6) >> exp) - 0x400;
        } else
                state_ptr->sr[0] = 0x20 - 0x400;
#endif

        /* DELAY A */
        state_ptr->pk[1] = state_ptr->pk[0];
        state_ptr->pk[0] = pk0;

        /* TONE */
        if (tr == 1)            /* this sample has been treated as data */
                state_ptr->td = 0;      /* next one will be treated as voice */
        else if (a2p < -11776)  /* small sample-to-sample correlation */
                state_ptr->td = 1;      /* signal may be data */
        else                            /* signal is voice */
                state_ptr->td = 0;

        /*
         * Adaptation speed control.
         */
        state_ptr->dms += (fi - state_ptr->dms) >> 5;           /* FILTA */
        state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);  /* FILTB */

        if (tr == 1)
                state_ptr->ap = 256;
        else if (y < 1536)                                      /* SUBTC */
                state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
        else if (state_ptr->td == 1)
                state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
        else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
            (state_ptr->dml >> 3))
                state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
        else
                state_ptr->ap += (-state_ptr->ap) >> 4;
}

/*
 * g726_decode()
 *
 * Description:
 *
 * Decodes a 4-bit code of G.726-32 encoded data of i and
 * returns the resulting linear PCM, A-law or u-law value.
 * return -1 for unknown out_coding value.
 */
static int g726_decode(int      i, struct g726_state *state_ptr)
{
        int             sezi, sez, se;  /* ACCUM */
        int             y;                      /* MIX */
        int             sr;                     /* ADDB */
        int             dq;
        int             dqsez;

        i &= 0x0f;                      /* mask to get proper bits */
#ifdef NOT_BLI
        sezi = predictor_zero(state_ptr);
        sez = sezi;
        se = sezi + predictor_pole(state_ptr);  /* estimated signal */
#else
        sezi = predictor_zero(state_ptr);
        sez = sezi >> 1;
        se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
#endif

        y = step_size(state_ptr);       /* dynamic quantizer step size */

        dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized diff. */

#ifdef NOT_BLI
        sr = se + dq;                           /* reconst. signal */
        dqsez = dq + sez;                       /* pole prediction diff. */
#else
        sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
        dqsez = sr - se + sez;          /* pole prediction diff. */
#endif

        update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);

#ifdef NOT_BLI
        return (sr >> 10);      /* sr was 26-bit dynamic range */
#else
        return (sr << 2);       /* sr was 14-bit dynamic range */
#endif
}

/*
 * g726_encode()
 *
 * Encodes the input vale of linear PCM, A-law or u-law data sl and returns
 * the resulting code. -1 is returned for unknown input coding value.
 */
static int g726_encode(int sl, struct g726_state *state_ptr)
{
        int             sezi, se, sez;          /* ACCUM */
        int             d;                      /* SUBTA */
        int             sr;                     /* ADDB */
        int             y;                      /* MIX */
        int             dqsez;                  /* ADDC */
        int             dq, i;

#ifdef NOT_BLI
        sl <<= 10;                      /* 26-bit dynamic range */

        sezi = predictor_zero(state_ptr);
        sez = sezi;
        se = sezi + predictor_pole(state_ptr);  /* estimated signal */
#else
        sl >>= 2;                       /* 14-bit dynamic range */

        sezi = predictor_zero(state_ptr);
        sez = sezi >> 1;
        se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
#endif

        d = sl - se;                            /* estimation difference */

        /* quantize the prediction difference */
        y = step_size(state_ptr);               /* quantizer step size */
#ifdef NOT_BLI
        d /= 0x1000;
#endif
        i = quantize(d, y, qtab_721, 7);        /* i = G726 code */

        dq = reconstruct(i & 8, _dqlntab[i], y);        /* quantized est diff */

#ifdef NOT_BLI
        sr = se + dq;                           /* reconst. signal */
        dqsez = dq + sez;                       /* pole prediction diff. */
#else
        sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
        dqsez = sr - se + sez;                  /* pole prediction diff. */
#endif

        update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);

        return (i);
}

/*
 * Private workspace for translating signed linear signals to G726.
 * Don't bother to define two distinct structs.
 */

struct g726_coder_pvt {
        /* buffer any odd byte in input - 0x80 + (value & 0xf) if present */
        unsigned char next_flag;
        struct g726_state g726;
};

/*! \brief init a new instance of g726_coder_pvt. */
static int lintog726_new(struct ast_trans_pvt *pvt)
{
        struct g726_coder_pvt *tmp = pvt->pvt;

        g726_init_state(&tmp->g726);

        return 0;
}

/*! \brief decode packed 4-bit G726 values (AAL2 packing) and store in buffer. */
static int g726aal2tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
{
        struct g726_coder_pvt *tmp = pvt->pvt;
        unsigned char *src = f->data;
        int16_t *dst = (int16_t *) pvt->outbuf + pvt->samples;
        unsigned int i;

        for (i = 0; i < f->datalen; i++) {
                *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
                *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
        }

        pvt->samples += f->samples;
        pvt->datalen += 2 * f->samples; /* 2 bytes/sample */

        return 0;
}

/*! \brief compress and store data (4-bit G726 samples, AAL2 packing) in outbuf */
static int lintog726aal2_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
{
        struct g726_coder_pvt *tmp = pvt->pvt;
        int16_t *src = f->data;
        unsigned int i;

        for (i = 0; i < f->samples; i++) {
                unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */

                if (tmp->next_flag & 0x80) {    /* merge with leftover sample */
                        pvt->outbuf[pvt->datalen++] = ((tmp->next_flag & 0xf)<< 4) | d;
                        pvt->samples += 2;      /* 2 samples per byte */
                        tmp->next_flag = 0;
                } else {
                        tmp->next_flag = 0x80 | d;
                }
        }

        return 0;
}

/*! \brief decode packed 4-bit G726 values (RFC3551 packing) and store in buffer. */
static int g726tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
{
        struct g726_coder_pvt *tmp = pvt->pvt;
        unsigned char *src = f->data;
        int16_t *dst = (int16_t *) pvt->outbuf + pvt->samples;
        unsigned int i;

        for (i = 0; i < f->datalen; i++) {
                *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
                *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
        }

        pvt->samples += f->samples;
        pvt->datalen += 2 * f->samples; /* 2 bytes/sample */

        return 0;
}

/*! \brief compress and store data (4-bit G726 samples, RFC3551 packing) in outbuf */
static int lintog726_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
{
        struct g726_coder_pvt *tmp = pvt->pvt;
        int16_t *src = f->data;
        unsigned int i;

        for (i = 0; i < f->samples; i++) {
                unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */

                if (tmp->next_flag & 0x80) {    /* merge with leftover sample */
                        pvt->outbuf[pvt->datalen++] = (d << 4) | (tmp->next_flag & 0xf);
                        pvt->samples += 2;      /* 2 samples per byte */
                        tmp->next_flag = 0;
                } else {
                        tmp->next_flag = 0x80 | d;
                }
        }

        return 0;
}

/*! \brief convert G726-32 RFC3551 packed data into AAL2 packed data (or vice-versa) */
static int g726tog726aal2_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
{
        unsigned char *src = f->data;
        unsigned char *dst = (unsigned char *) pvt->outbuf + pvt->samples;
        unsigned int i;

        for (i = 0; i < f->datalen; i++)
                *dst++ = ((src[i] & 0xf) << 4) | (src[i] >> 4);

        pvt->samples += f->samples;
        pvt->datalen += f->samples; /* 1 byte/sample */

        return 0;
}

static struct ast_frame *g726tolin_sample(void)
{
        static struct ast_frame f = {
                .frametype = AST_FRAME_VOICE,
                .subclass = AST_FORMAT_G726,
                .datalen = sizeof(g726_slin_ex),
                .samples = sizeof(g726_slin_ex) * 2,    /* 2 samples per byte */
                .src = __PRETTY_FUNCTION__,
                .data = g726_slin_ex,
        };

        return &f;
}

static struct ast_frame *lintog726_sample (void)
{
        static struct ast_frame f = {
                .frametype = AST_FRAME_VOICE,
                .subclass = AST_FORMAT_SLINEAR,
                .datalen = sizeof(slin_g726_ex),
                .samples = sizeof(slin_g726_ex) / 2,    /* 1 sample per 2 bytes */
                .src = __PRETTY_FUNCTION__,
                .data = slin_g726_ex,
        };

        return &f;
}

static struct ast_translator g726tolin = {
        .name = "g726tolin",
        .srcfmt = AST_FORMAT_G726,
        .dstfmt = AST_FORMAT_SLINEAR,
        .newpvt = lintog726_new,        /* same for both directions */
        .framein = g726tolin_framein,
        .sample = g726tolin_sample,
        .desc_size = sizeof(struct g726_coder_pvt),
        .buffer_samples = BUFFER_SAMPLES,
        .buf_size = BUFFER_SAMPLES * 2,
        .plc_samples = 160,
};

static struct ast_translator lintog726 = {
        .name = "lintog726",
        .srcfmt = AST_FORMAT_SLINEAR,
        .dstfmt = AST_FORMAT_G726,
        .newpvt = lintog726_new,        /* same for both directions */
        .framein = lintog726_framein,
        .sample = lintog726_sample,
        .desc_size = sizeof(struct g726_coder_pvt),
        .buffer_samples = BUFFER_SAMPLES,
        .buf_size = BUFFER_SAMPLES/2,
};

static struct ast_translator g726aal2tolin = {
        .name = "g726aal2tolin",
        .srcfmt = AST_FORMAT_G726_AAL2,
        .dstfmt = AST_FORMAT_SLINEAR,
        .newpvt = lintog726_new,        /* same for both directions */
        .framein = g726aal2tolin_framein,
        .sample = g726tolin_sample,
        .desc_size = sizeof(struct g726_coder_pvt),
        .buffer_samples = BUFFER_SAMPLES,
        .buf_size = BUFFER_SAMPLES * 2,
        .plc_samples = 160,
};

static struct ast_translator lintog726aal2 = {
        .name = "lintog726aal2",
        .srcfmt = AST_FORMAT_SLINEAR,
        .dstfmt = AST_FORMAT_G726_AAL2,
        .newpvt = lintog726_new,        /* same for both directions */
        .framein = lintog726aal2_framein,
        .sample = lintog726_sample,
        .desc_size = sizeof(struct g726_coder_pvt),
        .buffer_samples = BUFFER_SAMPLES,
        .buf_size = BUFFER_SAMPLES / 2,
};

static struct ast_translator g726tog726aal2 = {
        .name = "g726tog726aal2",
        .srcfmt = AST_FORMAT_G726,
        .dstfmt = AST_FORMAT_G726_AAL2,
        .framein = g726tog726aal2_framein,      /* same for both directions */
        .sample = lintog726_sample,
        .buffer_samples = BUFFER_SAMPLES,
        .buf_size = BUFFER_SAMPLES,
};

static struct ast_translator g726aal2tog726 = {
        .name = "g726aal2tog726",
        .srcfmt = AST_FORMAT_G726_AAL2,
        .dstfmt = AST_FORMAT_G726,
        .framein = g726tog726aal2_framein,      /* same for both directions */
        .sample = lintog726_sample,
        .buffer_samples = BUFFER_SAMPLES,
        .buf_size = BUFFER_SAMPLES,
};

static void parse_config(void)
{
        struct ast_variable *var;
        struct ast_config *cfg = ast_config_load("codecs.conf");

        if (!cfg)
                return;
        for (var = ast_variable_browse(cfg, "plc"); var; var = var->next) {
                if (!strcasecmp(var->name, "genericplc")) {
                        g726tolin.useplc = ast_true(var->value) ? 1 : 0;
                        if (option_verbose > 2)
                                ast_verbose(VERBOSE_PREFIX_3 "codec_g726: %susing generic PLC\n",
                                        g726tolin.useplc ? "" : "not ");
                }
        }
        ast_config_destroy(cfg);
}

static int reload(void)
{
        parse_config();

        return 0;
}

static int unload_module(void)
{
        int res = 0;

        res |= ast_unregister_translator(&g726tolin);
        res |= ast_unregister_translator(&lintog726);

        res |= ast_unregister_translator(&g726aal2tolin);
        res |= ast_unregister_translator(&lintog726aal2);

        res |= ast_unregister_translator(&g726aal2tog726);
        res |= ast_unregister_translator(&g726tog726aal2);

        return res;
}

static int load_module(void)
{
        int res = 0;


        parse_config();

        res |= ast_register_translator(&g726tolin);
        res |= ast_register_translator(&lintog726);

        res |= ast_register_translator(&g726aal2tolin);
        res |= ast_register_translator(&lintog726aal2);

        res |= ast_register_translator(&g726aal2tog726);
        res |= ast_register_translator(&g726tog726aal2);

        if (res)
                unload_module();

        return res;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "ITU G.726-32kbps G726 Transcoder",
                .load = load_module,
                .unload = unload_module,
                .reload = reload,
               );