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cx_g726.h

/*
 * 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
 *
 * $Id: cx_g726.h,v 1.3 2000/01/27 17:11:32 ucacoxh Exp $
 */

/*
 * cx_g726.h
 *
 * Header file for CCITT conversion routines.
 */
#ifndef _G726_H
#define     _G726_H

#define     AUDIO_ENCODING_ULAW     (1)   /* ISDN u-law */
#define     AUDIO_ENCODING_ALAW     (2)   /* ISDN A-law */
#define     AUDIO_ENCODING_LINEAR   (3)   /* PCM 2's-complement (0-center) */

/*
 * The following is the definition of the state structure
 * used by the G.726_32/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.726_32.  The field names are essentially indentical
 * 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. */
      short yu;   /* Unlocked or non-steady state step size multiplier. */
      short dms;  /* Short term energy estimate. */
      short dml;  /* Long term energy estimate. */
      short ap;   /* Linear weighting coefficient of 'yl' and 'yu'. */

      short a[2]; /* Coefficients of pole portion of prediction filter. */
      short b[6]; /* Coefficients of zero portion of prediction filter. */
      short pk[2];      /*
                   * Signs of previous two samples of a partially
                   * reconstructed signal.
                   */
      short dq[6];      /*
                   * Previous 6 samples of the quantized difference
                   * signal represented in an internal floating point
                   * format.
                   */
      short sr[2];      /*
                   * Previous 2 samples of the quantized difference
                   * signal represented in an internal floating point
                   * format.
                   */
      char td;    /* delayed tone detect, new in 1988 version */
};

/* External function definitions. */

extern void g726_init_state(struct g726_state *);
extern int g726_16_encoder(
            int sample,
            int in_coding,
            struct g726_state *state_ptr);
extern int g726_16_decoder(
            int code,
            int out_coding,
            struct g726_state *state_ptr);
extern int g726_24_encoder(
            int sample,
            int in_coding,
            struct g726_state *state_ptr);
extern int g726_24_decoder(
            int code,
            int out_coding,
            struct g726_state *state_ptr);
extern int g726_32_encoder(
            int sample,
            int in_coding,
            struct g726_state *state_ptr);
extern int g726_32_decoder(
            int code,
            int out_coding,
            struct g726_state *state_ptr);
extern int g726_40_encoder(
            int sample,
            int in_coding,
            struct g726_state *state_ptr);
extern int g726_40_decoder(
            int code,
            int out_coding,
            struct g726_state *state_ptr);

/* Internal function definitions */
#ifdef _PRIVATE_G726_
int predictor_zero(struct g726_state *state_ptr);
int predictor_pole(struct g726_state *state_ptr);
int step_size(struct g726_state *state_ptr);
int quantize(int d, int y, short *table, int size);
int reconstruct(int sign, int dqln, int y);
void
update(int code_size, int y, int wi, int fi, int dq, int sr, int dqsez, struct g726_state *state_ptr);

#endif /* _PRIVATE_G726_ */

#endif /* !_G726_H */

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