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freeswitch/libs/spandsp/src/g726.c

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/*
* SpanDSP - a series of DSP components for telephony
*
* g726.c - The ITU G.726 codec.
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2006 Steve Underwood
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1,
* as published by the Free Software Foundation.
*
* This program 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Based on G.721/G.723 code which is:
*
* This source code is a product of Sun Microsystems, Inc. and is provided
* for unrestricted use. Users may copy or modify this source code without
* charge.
*
* SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
* THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
* PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
*
* Sun source code is provided with no support and without any obligation on
* the part of Sun Microsystems, Inc. to assist in its use, correction,
* modification or enhancement.
*
* SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
* INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
* OR ANY PART THEREOF.
*
* In no event will Sun Microsystems, Inc. be liable for any lost revenue
* or profits or other special, indirect and consequential damages, even if
* Sun has been advised of the possibility of such damages.
*
* Sun Microsystems, Inc.
* 2550 Garcia Avenue
* Mountain View, California 94043
*/
/*! \file */
#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif
#include <inttypes.h>
#include <memory.h>
#include <stdlib.h>
#if defined(HAVE_TGMATH_H)
#include <tgmath.h>
#endif
#if defined(HAVE_MATH_H)
#include <math.h>
#endif
#if defined(HAVE_STDBOOL_H)
#include <stdbool.h>
#else
#include "spandsp/stdbool.h"
#endif
#include "floating_fudge.h"
#include "spandsp/telephony.h"
#include "spandsp/alloc.h"
#include "spandsp/bitstream.h"
#include "spandsp/bit_operations.h"
#include "spandsp/g711.h"
#include "spandsp/g726.h"
#include "spandsp/private/bitstream.h"
#include "spandsp/private/g726.h"
/*
* Maps G.726_16 code word to reconstructed scale factor normalized log
* magnitude values.
*/
static const int g726_16_dqlntab[4] =
{
116, 365, 365, 116
};
/* Maps G.726_16 code word to log of scale factor multiplier. */
static const int g726_16_witab[4] =
{
-704, 14048, 14048, -704
};
/*
* Maps G.726_16 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 const int g726_16_fitab[4] =
{
0x000, 0xE00, 0xE00, 0x000
};
static const int qtab_726_16[1] =
{
261
};
/*
* Maps G.726_24 code word to reconstructed scale factor normalized log
* magnitude values.
*/
static const int g726_24_dqlntab[8] =
{
-2048, 135, 273, 373, 373, 273, 135, -2048
};
/* Maps G.726_24 code word to log of scale factor multiplier. */
static const int g726_24_witab[8] =
{
-128, 960, 4384, 18624, 18624, 4384, 960, -128
};
/*
* Maps G.726_24 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 const int g726_24_fitab[8] =
{
0x000, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0x000
};
static const int qtab_726_24[3] =
{
8, 218, 331
};
/*
* Maps G.726_32 code word to reconstructed scale factor normalized log
* magnitude values.
*/
static const int g726_32_dqlntab[16] =
{
-2048, 4, 135, 213, 273, 323, 373, 425,
425, 373, 323, 273, 213, 135, 4, -2048
};
/* Maps G.726_32 code word to log of scale factor multiplier. */
static const int g726_32_witab[16] =
{
-384, 576, 1312, 2048, 3584, 6336, 11360, 35904,
35904, 11360, 6336, 3584, 2048, 1312, 576, -384
};
/*
* Maps G.726_32 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 const int g726_32_fitab[16] =
{
0x000, 0x000, 0x000, 0x200, 0x200, 0x200, 0x600, 0xE00,
0xE00, 0x600, 0x200, 0x200, 0x200, 0x000, 0x000, 0x000
};
static const int qtab_726_32[7] =
{
-124, 80, 178, 246, 300, 349, 400
};
/*
* Maps G.726_40 code word to ructeconstructed scale factor normalized log
* magnitude values.
*/
static const int g726_40_dqlntab[32] =
{
-2048, -66, 28, 104, 169, 224, 274, 318,
358, 395, 429, 459, 488, 514, 539, 566,
566, 539, 514, 488, 459, 429, 395, 358,
318, 274, 224, 169, 104, 28, -66, -2048
};
/* Maps G.726_40 code word to log of scale factor multiplier. */
static const int g726_40_witab[32] =
{
448, 448, 768, 1248, 1280, 1312, 1856, 3200,
4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272,
22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512,
3200, 1856, 1312, 1280, 1248, 768, 448, 448
};
/*
* Maps G.726_40 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 const int g726_40_fitab[32] =
{
0x000, 0x000, 0x000, 0x000, 0x000, 0x200, 0x200, 0x200,
0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00,
0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200,
0x200, 0x200, 0x200, 0x000, 0x000, 0x000, 0x000, 0x000
};
static const int qtab_726_40[15] =
{
-122, -16, 68, 139, 198, 250, 298, 339,
378, 413, 445, 475, 502, 528, 553
};
/*
* returns the integer product of the 14-bit integer "an" and
* "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
*/
static int16_t fmult(int16_t an, int16_t srn)
{
int16_t anmag;
int16_t anexp;
int16_t anmant;
int16_t wanexp;
int16_t wanmant;
int16_t retval;
anmag = (an > 0) ? an : ((-an) & 0x1FFF);
anexp = (int16_t) (top_bit(anmag) - 5);
anmant = (anmag == 0) ? 32 : (anexp >= 0) ? (anmag >> anexp) : (anmag << -anexp);
wanexp = anexp + ((srn >> 6) & 0xF) - 13;
wanmant = (anmant*(srn & 0x3F) + 0x30) >> 4;
retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) : (wanmant >> -wanexp);
return (((an ^ srn) < 0) ? -retval : retval);
}
/*- End of function --------------------------------------------------------*/
/*
* Compute the estimated signal from the 6-zero predictor.
*/
static __inline__ int16_t predictor_zero(g726_state_t *s)
{
int i;
int sezi;
sezi = fmult(s->b[0] >> 2, s->dq[0]);
/* ACCUM */
for (i = 1; i < 6; i++)
sezi += fmult(s->b[i] >> 2, s->dq[i]);
return (int16_t) sezi;
}
/*- End of function --------------------------------------------------------*/
/*
* Computes the estimated signal from the 2-pole predictor.
*/
static __inline__ int16_t predictor_pole(g726_state_t *s)
{
return (fmult(s->a[1] >> 2, s->sr[1]) + fmult(s->a[0] >> 2, s->sr[0]));
}
/*- End of function --------------------------------------------------------*/
/*
* Computes the quantization step size of the adaptive quantizer.
*/
static int step_size(g726_state_t *s)
{
int y;
int dif;
int al;
if (s->ap >= 256)
return s->yu;
y = s->yl >> 6;
dif = s->yu - y;
al = s->ap >> 2;
if (dif > 0)
y += (dif*al) >> 6;
else if (dif < 0)
y += (dif*al + 0x3F) >> 6;
return y;
}
/*- End of function --------------------------------------------------------*/
/*
* 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 int16_t quantize(int d, /* Raw difference signal sample */
int y, /* Step size multiplier */
const int table[], /* quantization table */
int quantizer_states) /* table size of int16_t integers */
{
int16_t dqm; /* Magnitude of 'd' */
int16_t exp; /* Integer part of base 2 log of 'd' */
int16_t mant; /* Fractional part of base 2 log */
int16_t dl; /* Log of magnitude of 'd' */
int16_t dln; /* Step size scale factor normalized log */
int i;
int size;
/*
* LOG
*
* Compute base 2 log of 'd', and store in 'dl'.
*/
dqm = (int16_t) abs(d);
exp = (int16_t) (top_bit(dqm >> 1) + 1);
/* Fractional portion. */
mant = ((dqm << 7) >> exp) & 0x7F;
dl = (exp << 7) + mant;
/*
* SUBTB
*
* "Divide" by step size multiplier.
*/
dln = dl - (int16_t) (y >> 2);
/*
* QUAN
*
* Search for codword i for 'dln'.
*/
size = (quantizer_states - 1) >> 1;
for (i = 0; i < size; i++)
{
if (dln < table[i])
break;
}
if (d < 0)
{
/* Take 1's complement of i */
return (int16_t) ((size << 1) + 1 - i);
}
if (i == 0 && (quantizer_states & 1))
{
/* Zero is only valid if there are an even number of states, so
take the 1's complement if the code is zero. */
return (int16_t) quantizer_states;
}
return (int16_t) i;
}
/*- End of function --------------------------------------------------------*/
/*
* 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 int16_t reconstruct(int sign, /* 0 for non-negative value */
int dqln, /* G.72x codeword */
int y) /* Step size multiplier */
{
int16_t dql; /* Log of 'dq' magnitude */
int16_t dex; /* Integer part of log */
int16_t dqt;
int16_t dq; /* Reconstructed difference signal sample */
dql = (int16_t) (dqln + (y >> 2)); /* ADDA */
if (dql < 0)
return ((sign) ? -0x8000 : 0);
/* ANTILOG */
dex = (dql >> 7) & 15;
dqt = 128 + (dql & 127);
dq = (dqt << 7) >> (14 - dex);
return ((sign) ? (dq - 0x8000) : dq);
}
/*- End of function --------------------------------------------------------*/
/*
* updates the state variables for each output code
*/
static void update(g726_state_t *s,
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 */
{
int16_t mag;
int16_t exp;
int16_t a2p; /* LIMC */
int16_t a1ul; /* UPA1 */
int16_t pks1; /* UPA2 */
int16_t fa1;
int16_t ylint;
int16_t dqthr;
int16_t ylfrac;
int16_t thr;
int16_t pk0;
int i;
bool tr;
a2p = 0;
/* Needed in updating predictor poles */
pk0 = (dqsez < 0) ? 1 : 0;
/* prediction difference magnitude */
mag = (int16_t) (dq & 0x7FFF);
/* TRANS */
ylint = (int16_t) (s->yl >> 15); /* exponent part of yl */
ylfrac = (int16_t) ((s->yl >> 10) & 0x1F); /* fractional part of yl */
/* Limit threshold to 31 << 10 */
thr = (ylint > 9) ? (31 << 10) : ((32 + ylfrac) << ylint);
dqthr = (thr + (thr >> 1)) >> 1; /* dqthr = 0.75 * thr */
if (!s->td) /* signal supposed voice */
tr = false;
else if (mag <= dqthr) /* supposed data, but small mag */
tr = false; /* treated as voice */
else /* signal is data (modem) */
tr = true;
/*
* Quantizer scale factor adaptation.
*/
/* FUNCTW & FILTD & DELAY */
/* update non-steady state step size multiplier */
s->yu = (int16_t) (y + ((wi - y) >> 5));
/* LIMB */
if (s->yu < 544)
s->yu = 544;
else if (s->yu > 5120)
s->yu = 5120;
/* FILTE & DELAY */
/* update steady state step size multiplier */
s->yl += s->yu + ((-s->yl) >> 6);
/*
* Adaptive predictor coefficients.
*/
if (tr)
{
/* Reset the a's and b's for a modem signal */
s->a[0] = 0;
s->a[1] = 0;
s->b[0] = 0;
s->b[1] = 0;
s->b[2] = 0;
s->b[3] = 0;
s->b[4] = 0;
s->b[5] = 0;
}
else
{
/* Update the a's and b's */
/* UPA2 */
pks1 = pk0 ^ s->pk[0];
/* Update predictor pole a[1] */
a2p = s->a[1] - (s->a[1] >> 7);
if (dqsez != 0)
{
fa1 = (pks1) ? s->a[0] : -s->a[0];
/* a2p = function of fa1 */
if (fa1 < -8191)
a2p -= 0x100;
else if (fa1 > 8191)
a2p += 0xFF;
else
a2p += fa1 >> 5;
if (pk0 ^ s->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 */
s->a[1] = a2p;
/* UPA1 */
/* Update predictor pole a[0] */
s->a[0] -= s->a[0] >> 8;
if (dqsez != 0)
{
if (pks1 == 0)
s->a[0] += 192;
else
s->a[0] -= 192;
}
/* LIMD */
a1ul = 15360 - a2p;
if (s->a[0] < -a1ul)
s->a[0] = -a1ul;
else if (s->a[0] > a1ul)
s->a[0] = a1ul;
/* UPB : update predictor zeros b[6] */
for (i = 0; i < 6; i++)
{
/* Distinguish 40Kbps mode from the others */
s->b[i] -= s->b[i] >> ((s->bits_per_sample == 5) ? 9 : 8);
if (dq & 0x7FFF)
{
/* XOR */
if ((dq ^ s->dq[i]) >= 0)
s->b[i] += 128;
else
s->b[i] -= 128;
}
}
}
for (i = 5; i > 0; i--)
s->dq[i] = s->dq[i - 1];
/* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
if (mag == 0)
{
s->dq[0] = (dq >= 0) ? 0x20 : 0xFC20;
}
else
{
exp = (int16_t) (top_bit(mag) + 1);
s->dq[0] = (dq >= 0)
? ((exp << 6) + ((mag << 6) >> exp))
: ((exp << 6) + ((mag << 6) >> exp) - 0x400);
}
s->sr[1] = s->sr[0];
/* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
if (sr == 0)
{
s->sr[0] = 0x20;
}
else if (sr > 0)
{
exp = (int16_t) (top_bit(sr) + 1);
s->sr[0] = (int16_t) ((exp << 6) + ((sr << 6) >> exp));
}
else if (sr > -32768)
{
mag = (int16_t) -sr;
exp = (int16_t) (top_bit(mag) + 1);
s->sr[0] = (exp << 6) + ((mag << 6) >> exp) - 0x400;
}
else
{
s->sr[0] = (uint16_t) 0xFC20;
}
/* DELAY A */
s->pk[1] = s->pk[0];
s->pk[0] = pk0;
/* TONE */
if (tr) /* this sample has been treated as data */
s->td = false; /* next one will be treated as voice */
else if (a2p < -11776) /* small sample-to-sample correlation */
s->td = true; /* signal may be data */
else /* signal is voice */
s->td = false;
/* Adaptation speed control. */
/* FILTA */
s->dms += ((int16_t) fi - s->dms) >> 5;
/* FILTB */
s->dml += (((int16_t) (fi << 2) - s->dml) >> 7);
if (tr)
s->ap = 256;
else if (y < 1536) /* SUBTC */
s->ap += (0x200 - s->ap) >> 4;
else if (s->td)
s->ap += (0x200 - s->ap) >> 4;
else if (abs((s->dms << 2) - s->dml) >= (s->dml >> 3))
s->ap += (0x200 - s->ap) >> 4;
else
s->ap += (-s->ap) >> 4;
}
/*- End of function --------------------------------------------------------*/
static int16_t tandem_adjust_alaw(int16_t sr, /* decoder output linear PCM sample */
int se, /* predictor estimate sample */
int y, /* quantizer step size */
int i, /* decoder input code */
int sign,
const int qtab[],
int quantizer_states)
{
uint8_t sp; /* A-law compressed 8-bit code */
int16_t dx; /* prediction error */
int id; /* quantized prediction error */
int sd; /* adjusted A-law decoded sample value */
if (sr <= -32768)
sr = -1;
sp = linear_to_alaw((sr >> 1) << 3);
/* 16-bit prediction error */
dx = (int16_t) ((alaw_to_linear(sp) >> 2) - se);
id = quantize(dx, y, qtab, quantizer_states);
if (id == i)
{
/* No adjustment of sp required */
return (int16_t) sp;
}
/* sp adjustment needed */
/* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
/* 2's complement to biased unsigned */
if ((id ^ sign) > (i ^ sign))
{
/* sp adjusted to next lower value */
if (sp & 0x80)
sd = (sp == 0xD5) ? 0x55 : (((sp ^ 0x55) - 1) ^ 0x55);
else
sd = (sp == 0x2A) ? 0x2A : (((sp ^ 0x55) + 1) ^ 0x55);
}
else
{
/* sp adjusted to next higher value */
if (sp & 0x80)
sd = (sp == 0xAA) ? 0xAA : (((sp ^ 0x55) + 1) ^ 0x55);
else
sd = (sp == 0x55) ? 0xD5 : (((sp ^ 0x55) - 1) ^ 0x55);
}
return (int16_t) sd;
}
/*- End of function --------------------------------------------------------*/
static int16_t tandem_adjust_ulaw(int16_t sr, /* decoder output linear PCM sample */
int se, /* predictor estimate sample */
int y, /* quantizer step size */
int i, /* decoder input code */
int sign,
const int qtab[],
int quantizer_states)
{
uint8_t sp; /* u-law compressed 8-bit code */
int16_t dx; /* prediction error */
int id; /* quantized prediction error */
int sd; /* adjusted u-law decoded sample value */
if (sr <= -32768)
sr = 0;
sp = linear_to_ulaw(sr << 2);
/* 16-bit prediction error */
dx = (int16_t) ((ulaw_to_linear(sp) >> 2) - se);
id = quantize(dx, y, qtab, quantizer_states);
if (id == i)
{
/* No adjustment of sp required. */
return (int16_t) sp;
}
/* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
/* 2's complement to biased unsigned */
if ((id ^ sign) > (i ^ sign))
{
/* sp adjusted to next lower value */
if (sp & 0x80)
sd = (sp == 0xFF) ? 0x7E : (sp + 1);
else
sd = (sp == 0x00) ? 0x00 : (sp - 1);
}
else
{
/* sp adjusted to next higher value */
if (sp & 0x80)
sd = (sp == 0x80) ? 0x80 : (sp - 1);
else
sd = (sp == 0x7F) ? 0xFE : (sp + 1);
}
return (int16_t) sd;
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
*/
static uint8_t g726_16_encoder(g726_state_t *s, int16_t amp)
{
int y;
int16_t sei;
int16_t sezi;
int16_t se;
int16_t d;
int16_t sr;
int16_t dqsez;
int16_t dq;
int16_t i;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_16, 4);
dq = reconstruct(i & 2, g726_16_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_16_witab[i], g726_16_fitab[i], dq, sr, dqsez);
return (uint8_t) i;
}
/*- End of function --------------------------------------------------------*/
/*
* Decodes a 2-bit CCITT G.726_16 ADPCM code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static int16_t g726_16_decoder(g726_state_t *s, uint8_t code)
{
int16_t sezi;
int16_t sei;
int16_t se;
int16_t sr;
int16_t dq;
int16_t dqsez;
int y;
/* Mask to get proper bits */
code &= 0x03;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 2, g726_16_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_16_witab[code], g726_16_fitab[code], dq, sr, dqsez);
switch (s->ext_coding)
{
case G726_ENCODING_ALAW:
return tandem_adjust_alaw(sr, se, y, code, 2, qtab_726_16, 4);
case G726_ENCODING_ULAW:
return tandem_adjust_ulaw(sr, se, y, code, 2, qtab_726_16, 4);
}
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
*/
static uint8_t g726_24_encoder(g726_state_t *s, int16_t amp)
{
int16_t sei;
int16_t sezi;
int16_t se;
int16_t d;
int16_t sr;
int16_t dqsez;
int16_t dq;
int16_t i;
int y;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_24, 7);
dq = reconstruct(i & 4, g726_24_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_24_witab[i], g726_24_fitab[i], dq, sr, dqsez);
return (uint8_t) i;
}
/*- End of function --------------------------------------------------------*/
/*
* Decodes a 3-bit CCITT G.726_24 ADPCM code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static int16_t g726_24_decoder(g726_state_t *s, uint8_t code)
{
int16_t sezi;
int16_t sei;
int16_t se;
int16_t sr;
int16_t dq;
int16_t dqsez;
int y;
/* Mask to get proper bits */
code &= 0x07;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 4, g726_24_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_24_witab[code], g726_24_fitab[code], dq, sr, dqsez);
switch (s->ext_coding)
{
case G726_ENCODING_ALAW:
return tandem_adjust_alaw(sr, se, y, code, 4, qtab_726_24, 7);
case G726_ENCODING_ULAW:
return tandem_adjust_ulaw(sr, se, y, code, 4, qtab_726_24, 7);
}
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a linear input sample and returns its 4-bit code.
*/
static uint8_t g726_32_encoder(g726_state_t *s, int16_t amp)
{
int16_t sei;
int16_t sezi;
int16_t se;
int16_t d;
int16_t sr;
int16_t dqsez;
int16_t dq;
int16_t i;
int y;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize the prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_32, 15);
dq = reconstruct(i & 8, g726_32_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_32_witab[i], g726_32_fitab[i], dq, sr, dqsez);
return (uint8_t) i;
}
/*- End of function --------------------------------------------------------*/
/*
* Decodes a 4-bit CCITT G.726_32 ADPCM code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static int16_t g726_32_decoder(g726_state_t *s, uint8_t code)
{
int16_t sezi;
int16_t sei;
int16_t se;
int16_t sr;
int16_t dq;
int16_t dqsez;
int y;
/* Mask to get proper bits */
code &= 0x0F;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 8, g726_32_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_32_witab[code], g726_32_fitab[code], dq, sr, dqsez);
switch (s->ext_coding)
{
case G726_ENCODING_ALAW:
return tandem_adjust_alaw(sr, se, y, code, 8, qtab_726_32, 15);
case G726_ENCODING_ULAW:
return tandem_adjust_ulaw(sr, se, y, code, 8, qtab_726_32, 15);
}
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens
* the resulting 5-bit CCITT G.726 40Kbps code.
*/
static uint8_t g726_40_encoder(g726_state_t *s, int16_t amp)
{
int16_t sei;
int16_t sezi;
int16_t se;
int16_t d;
int16_t sr;
int16_t dqsez;
int16_t dq;
int16_t i;
int y;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_40, 31);
dq = reconstruct(i & 0x10, g726_40_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_40_witab[i], g726_40_fitab[i], dq, sr, dqsez);
return (uint8_t) i;
}
/*- End of function --------------------------------------------------------*/
/*
* Decodes a 5-bit CCITT G.726 40Kbps code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static int16_t g726_40_decoder(g726_state_t *s, uint8_t code)
{
int16_t sezi;
int16_t sei;
int16_t se;
int16_t sr;
int16_t dq;
int16_t dqsez;
int y;
/* Mask to get proper bits */
code &= 0x1F;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 0x10, g726_40_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_40_witab[code], g726_40_fitab[code], dq, sr, dqsez);
switch (s->ext_coding)
{
case G726_ENCODING_ALAW:
return tandem_adjust_alaw(sr, se, y, code, 0x10, qtab_726_40, 31);
case G726_ENCODING_ULAW:
return tandem_adjust_ulaw(sr, se, y, code, 0x10, qtab_726_40, 31);
}
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(g726_state_t *) g726_init(g726_state_t *s, int bit_rate, int ext_coding, int packing)
{
int i;
if (bit_rate != 16000 && bit_rate != 24000 && bit_rate != 32000 && bit_rate != 40000)
return NULL;
if (s == NULL)
{
if ((s = (g726_state_t *) span_alloc(sizeof(*s))) == NULL)
return NULL;
}
s->yl = 34816;
s->yu = 544;
s->dms = 0;
s->dml = 0;
s->ap = 0;
s->rate = bit_rate;
s->ext_coding = ext_coding;
s->packing = packing;
for (i = 0; i < 2; i++)
{
s->a[i] = 0;
s->pk[i] = 0;
s->sr[i] = 32;
}
for (i = 0; i < 6; i++)
{
s->b[i] = 0;
s->dq[i] = 32;
}
s->td = false;
switch (bit_rate)
{
case 16000:
s->enc_func = g726_16_encoder;
s->dec_func = g726_16_decoder;
s->bits_per_sample = 2;
break;
case 24000:
s->enc_func = g726_24_encoder;
s->dec_func = g726_24_decoder;
s->bits_per_sample = 3;
break;
case 32000:
default:
s->enc_func = g726_32_encoder;
s->dec_func = g726_32_decoder;
s->bits_per_sample = 4;
break;
case 40000:
s->enc_func = g726_40_encoder;
s->dec_func = g726_40_decoder;
s->bits_per_sample = 5;
break;
}
bitstream_init(&s->bs, (s->packing != G726_PACKING_LEFT));
return s;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) g726_release(g726_state_t *s)
{
return 0;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) g726_free(g726_state_t *s)
{
span_free(s);
return 0;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) g726_decode(g726_state_t *s,
int16_t amp[],
const uint8_t g726_data[],
int g726_bytes)
{
int i;
int samples;
uint8_t code;
int sl;
for (samples = i = 0; ; )
{
if (s->packing != G726_PACKING_NONE)
{
/* Unpack the code bits */
if (s->packing != G726_PACKING_LEFT)
{
if (s->bs.residue < s->bits_per_sample)
{
if (i >= g726_bytes)
break;
s->bs.bitstream |= (g726_data[i++] << s->bs.residue);
s->bs.residue += 8;
}
code = (uint8_t) (s->bs.bitstream & ((1 << s->bits_per_sample) - 1));
s->bs.bitstream >>= s->bits_per_sample;
}
else
{
if (s->bs.residue < s->bits_per_sample)
{
if (i >= g726_bytes)
break;
s->bs.bitstream = (s->bs.bitstream << 8) | g726_data[i++];
s->bs.residue += 8;
}
code = (uint8_t) ((s->bs.bitstream >> (s->bs.residue - s->bits_per_sample)) & ((1 << s->bits_per_sample) - 1));
}
s->bs.residue -= s->bits_per_sample;
}
else
{
if (i >= g726_bytes)
break;
code = g726_data[i++];
}
sl = s->dec_func(s, code);
if (s->ext_coding != G726_ENCODING_LINEAR)
((uint8_t *) amp)[samples++] = (uint8_t) sl;
else
amp[samples++] = (int16_t) sl;
}
return samples;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) g726_encode(g726_state_t *s,
uint8_t g726_data[],
const int16_t amp[],
int len)
{
int i;
int g726_bytes;
int16_t sl;
uint8_t code;
for (g726_bytes = i = 0; i < len; i++)
{
/* Linearize the input sample to 14-bit PCM */
switch (s->ext_coding)
{
case G726_ENCODING_ALAW:
sl = alaw_to_linear(((const uint8_t *) amp)[i]) >> 2;
break;
case G726_ENCODING_ULAW:
sl = ulaw_to_linear(((const uint8_t *) amp)[i]) >> 2;
break;
default:
sl = amp[i] >> 2;
break;
}
code = s->enc_func(s, sl);
if (s->packing != G726_PACKING_NONE)
{
/* Pack the code bits */
if (s->packing != G726_PACKING_LEFT)
{
s->bs.bitstream |= (code << s->bs.residue);
s->bs.residue += s->bits_per_sample;
if (s->bs.residue >= 8)
{
g726_data[g726_bytes++] = (uint8_t) (s->bs.bitstream & 0xFF);
s->bs.bitstream >>= 8;
s->bs.residue -= 8;
}
}
else
{
s->bs.bitstream = (s->bs.bitstream << s->bits_per_sample) | code;
s->bs.residue += s->bits_per_sample;
if (s->bs.residue >= 8)
{
g726_data[g726_bytes++] = (uint8_t) ((s->bs.bitstream >> (s->bs.residue - 8)) & 0xFF);
s->bs.residue -= 8;
}
}
}
else
{
g726_data[g726_bytes++] = (uint8_t) code;
}
}
return g726_bytes;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/
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