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/* $Id: isdn_audio.h,v 1.1.1.1 2004-04-15 02:03:51 phoenix Exp $

 *

 * Linux ISDN subsystem, audio conversion and compression (linklevel).

 *

 * Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)

 *

 * This software may be used and distributed according to the terms

 * of the GNU General Public License, incorporated herein by reference.

 *

 */

#define DTMF_NPOINTS 205        /* Number of samples for DTMF recognition */

typedef struct adpcm_state {

        int a;

        int d;

        int word;

        int nleft;

        int nbits;

} adpcm_state;

typedef struct dtmf_state {

        char last;

        char llast;

        int idx;

        int buf[DTMF_NPOINTS];

} dtmf_state;

typedef struct silence_state {

        int state;

        unsigned int idx;

} silence_state;

extern void isdn_audio_ulaw2alaw(unsigned char *, unsigned long);

extern void isdn_audio_alaw2ulaw(unsigned char *, unsigned long);

extern adpcm_state *isdn_audio_adpcm_init(adpcm_state *, int);

extern int isdn_audio_adpcm2xlaw(adpcm_state *, int, unsigned char *, unsigned char *, int);

extern int isdn_audio_xlaw2adpcm(adpcm_state *, int, unsigned char *, unsigned char *, int);

extern int isdn_audio_2adpcm_flush(adpcm_state * s, unsigned char *out);

extern void isdn_audio_calc_dtmf(modem_info *, unsigned char *, int, int);

extern void isdn_audio_eval_dtmf(modem_info *);

dtmf_state *isdn_audio_dtmf_init(dtmf_state *);

extern void isdn_audio_calc_silence(modem_info *, unsigned char *, int, int);

extern void isdn_audio_eval_silence(modem_info *);

silence_state *isdn_audio_silence_init(silence_state *);

extern void isdn_audio_put_dle_code(modem_info *, u_char);