/* * 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 *//* * g723_24.c * * Description: * * g723_24_encoder(), g723_24_decoder() * * These routines comprise an implementation of the CCITT G.723 24 Kbps * ADPCM coding algorithm.  Essentially, this implementation is identical to * the bit level description except for a few deviations which take advantage * of workstation attributes, such as hardware 2's complement arithmetic. * */#include "g72x.h"/* * Maps G.723_24 code word to reconstructed scale factor normalized log * magnitude values. */static short	_dqlntab[8] = {-2048, 135, 273, 373, 373, 273, 135, -2048};/* Maps G.723_24 code word to log of scale factor multiplier. */static short	_witab[8] = {-128, 960, 4384, 18624, 18624, 4384, 960, -128};/* * Maps G.723_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 short	_fitab[8] = {0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0};static short qtab_723_24[3] = {8, 218, 331};/* * g723_24_encoder() * * Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code. * Returns -1 if invalid input coding value. */intg723_24_encoder(	int		sl,	int		in_coding,	struct g72x_state *state_ptr){	short		sei, sezi, se, sez;	/* ACCUM */	short		d;			/* SUBTA */	short		y;			/* MIX */	short		sr;			/* ADDB */	short		dqsez;			/* ADDC */	short		dq, i;	switch (in_coding) {	/* linearize input sample to 14-bit PCM */	case AUDIO_ENCODING_ALAW:		sl = alaw2linear(sl) >> 2;		break;	case AUDIO_ENCODING_ULAW:		sl = ulaw2linear(sl) >> 2;		break;	case AUDIO_ENCODING_LINEAR:		sl >>= 2;		/* sl of 14-bit dynamic range */		break;	default:		return (-1);	}	sezi = predictor_zero(state_ptr);	sez = sezi >> 1;	sei = sezi + predictor_pole(state_ptr);	se = sei >> 1;			/* se = estimated signal */	d = sl - se;			/* d = estimation diff. */	/* quantize prediction difference d */	y = step_size(state_ptr);	/* quantizer step size */	i = quantize(d, y, qtab_723_24, 3);	/* i = ADPCM code */	dq = reconstruct(i & 4, _dqlntab[i], y); /* quantized diff. */	sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */	dqsez = sr + sez - se;		/* pole prediction diff. */	update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);	return (i);}/* * g723_24_decoder() * * Decodes a 3-bit CCITT G.723_24 ADPCM code and returns * the resulting 16-bit linear PCM, A-law or u-law sample value. * -1 is returned if the output coding is unknown. */intg723_24_decoder(	int		i,	int		out_coding,	struct g72x_state *state_ptr){	short		sezi, sei, sez, se;	/* ACCUM */	short		y;			/* MIX */	short		sr;			/* ADDB */	short		dq;	short		dqsez;	i &= 0x07;			/* mask to get proper bits */	sezi = predictor_zero(state_ptr);	sez = sezi >> 1;	sei = sezi + predictor_pole(state_ptr);	se = sei >> 1;			/* se = estimated signal */	y = step_size(state_ptr);	/* adaptive quantizer step size */	dq = reconstruct(i & 0x04, _dqlntab[i], y); /* unquantize pred diff */	sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */	dqsez = sr - se + sez;			/* pole prediction diff. */	update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);	switch (out_coding) {	case AUDIO_ENCODING_ALAW:		return (tandem_adjust_alaw(sr, se, y, i, 4, qtab_723_24));	case AUDIO_ENCODING_ULAW:		return (tandem_adjust_ulaw(sr, se, y, i, 4, qtab_723_24));	case AUDIO_ENCODING_LINEAR:		return (sr << 2);	/* sr was of 14-bit dynamic range */	default:		return (-1);	}}