drivers/isdn/isdn_audio.h

   1 /* $Id: isdn_audio.h,v 1.7 1999/04/12 12:33:11 fritz 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 program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2, or (at your option)
  10  * any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  *
  21  * $Log: isdn_audio.h,v $
  22  * Revision 1.7  1999/04/12 12:33:11  fritz
  23  * Changes from 2.0 tree.
  24  *
  25  * Revision 1.6  1998/07/26 18:48:44  armin
  26  * Added silence detection in voice receive mode.
  27  *
  28  * Revision 1.5  1997/02/03 22:45:21  fritz
  29  * Reformatted according CodingStyle
  30  *
  31  * Revision 1.4  1996/06/06 14:43:32  fritz
  32  * Changed to support DTMF decoding on audio playback also.
  33  *
  34  * Revision 1.3  1996/06/05 02:24:09  fritz
  35  * Added DTMF decoder for audio mode.
  36  *
  37  * Revision 1.2  1996/05/10 08:48:32  fritz
  38  * Corrected adpcm bugs.
  39  *
  40  * Revision 1.1  1996/04/30 09:29:06  fritz
  41  * Taken under CVS control.
  42  *
  43  */
  44
  45 #define DTMF_NPOINTS 205        /* Number of samples for DTMF recognition */
  46 typedef struct adpcm_state {
  47         int a;
  48         int d;
  49         int word;
  50         int nleft;
  51         int nbits;
  52 } adpcm_state;
  53
  54 typedef struct dtmf_state {
  55         char last;
  56         int idx;
  57         int buf[DTMF_NPOINTS];
  58 } dtmf_state;
  59
  60 typedef struct silence_state {
  61         int state;
  62         unsigned int idx;
  63 } silence_state;
  64
  65 extern void isdn_audio_ulaw2alaw(unsigned char *, unsigned long);
  66 extern void isdn_audio_alaw2ulaw(unsigned char *, unsigned long);
  67 extern adpcm_state *isdn_audio_adpcm_init(adpcm_state *, int);
  68 extern int isdn_audio_adpcm2xlaw(adpcm_state *, int, unsigned char *, unsigned char *, int);
  69 extern int isdn_audio_xlaw2adpcm(adpcm_state *, int, unsigned char *, unsigned char *, int);
  70 extern int isdn_audio_2adpcm_flush(adpcm_state * s, unsigned char *out);
  71 extern void isdn_audio_calc_dtmf(modem_info *, unsigned char *, int, int);
  72 extern void isdn_audio_eval_dtmf(modem_info *);
  73 dtmf_state *isdn_audio_dtmf_init(dtmf_state *);
  74 extern void isdn_audio_calc_silence(modem_info *, unsigned char *, int, int);
  75 extern void isdn_audio_eval_silence(modem_info *);
  76 silence_state *isdn_audio_silence_init(silence_state *);