/* * 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 *//* * g721.c * * Description: * * g721_encoder(), g721_decoder() * * These routines comprise an implementation of the CCITT G.721 ADPCM * coding algorithm.  Essentially, this implementation is identical to * the bit level description except for a few deviations which * take advantage of work station attributes, such as hardware 2's * complement arithmetic and large memory.  Specifically, certain time * consuming operations such as multiplications are replaced * with lookup tables and software 2's complement operations are * replaced with hardware 2's complement. * * The deviation from the bit level specification (lookup tables) * preserves the bit level performance specifications. * * As outlined in the G.721 Recommendation, the algorithm is broken * down into modules.  Each section of code below is preceded by * the name of the module which it is implementing. * */#include "g72x.h"static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};/* * Maps G.721 code word to reconstructed scale factor normalized log * magnitude values. */static short	_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 short	_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 short	_fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,				0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};/* * g721_encoder() * * 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. */intg721_encoder(	int		sl,	int		in_coding,	struct g72x_state *state_ptr){	short		sezi, se, sez;		/* ACCUM */	short		d;			/* SUBTA */	short		sr;			/* ADDB */	short		y;			/* MIX */	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;			/* 14-bit dynamic range */		break;	default:		return (-1);	}	sezi = predictor_zero(state_ptr);	sez = sezi >> 1;	se = (sezi + predictor_pole(state_ptr)) >> 1;	/* estimated signal */	d = sl - se;				/* estimation difference */	/* quantize the prediction difference */	y = step_size(state_ptr);		/* quantizer step size */	i = quantize(d, y, qtab_721, 7);	/* i = ADPCM code */	dq = reconstruct(i & 8, _dqlntab[i], y);	/* quantized est diff */	sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;	/* reconst. signal */	dqsez = sr + sez - se;			/* pole prediction diff. */	update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);	return (i);}/* * g721_decoder() * * Description: * * Decodes a 4-bit code of G.721 encoded data of i and * returns the resulting linear PCM, A-law or u-law value. * return -1 for unknown out_coding value. */intg721_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 &= 0x0f;			/* 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);	/* dynamic quantizer step size */	dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */	sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq;	/* reconst. signal */	dqsez = sr - se + sez;			/* pole prediction diff. */	update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);	switch (out_coding) {	case AUDIO_ENCODING_ALAW:		return (tandem_adjust_alaw(sr, se, y, i, 8, qtab_721));	case AUDIO_ENCODING_ULAW:		return (tandem_adjust_ulaw(sr, se, y, i, 8, qtab_721));	case AUDIO_ENCODING_LINEAR:		return (sr << 2);	/* sr was 14-bit dynamic range */	default:		return (-1);	}}