LXR linux/drivers/isdn/i4l/isdn

   1/* $Id: isdn_audio.h,v 1.1.2.2 2004/01/12 22:37:18 keil Exp $
   2 *
   3 * Linux ISDN subsystem, audio conversion and compression (linklevel).
   4 *
   5 * Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)
   6 *
   7 * This software may be used and distributed according to the terms
   8 * of the GNU General Public License, incorporated herein by reference.
   9 *
  10 */
  11
  12#define DTMF_NPOINTS 205        /* Number of samples for DTMF recognition */
  13typedef struct adpcm_state {
  14        int a;
  15        int d;
  16        int word;
  17        int nleft;
  18        int nbits;
  19} adpcm_state;
  20
  21typedef struct dtmf_state {
  22        char last;
  23        char llast;
  24        int idx;
  25        int buf[DTMF_NPOINTS];
  26} dtmf_state;
  27
  28typedef struct silence_state {
  29        int state;
  30        unsigned int idx;
  31} silence_state;
  32
  33extern void isdn_audio_ulaw2alaw(unsigned char *, unsigned long);
  34extern void isdn_audio_alaw2ulaw(unsigned char *, unsigned long);
  35extern adpcm_state *isdn_audio_adpcm_init(adpcm_state *, int);
  36extern int isdn_audio_adpcm2xlaw(adpcm_state *, int, unsigned char *, unsigned char *, int);
  37extern int isdn_audio_xlaw2adpcm(adpcm_state *, int, unsigned char *, unsigned char *, int);
  38extern void isdn_audio_calc_dtmf(modem_info *, unsigned char *, int, int);
  39extern void isdn_audio_eval_dtmf(modem_info *);
  40dtmf_state *isdn_audio_dtmf_init(dtmf_state *);
  41extern void isdn_audio_calc_silence(modem_info *, unsigned char *, int, int);
  42extern void isdn_audio_eval_silence(modem_info *);
  43silence_state *isdn_audio_silence_init(silence_state *);
  44extern void isdn_audio_put_dle_code(modem_info *, u_char);
  45