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/* $Id: isdn_audio.c,v 1.1.1.1 2001-09-10 07:44:18 simons Exp $

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

 *

 * Copyright 1994-1998 by Fritz Elfert (fritz@isdn4linux.de)

 * DTMF code (c) 1996 by Christian Mock (cm@kukuruz.ping.at)

 * Silence detection (c) 1998 by Armin Schindler (mac@gismo.telekom.de)

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2, or (at your option)

 * any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 *

 * $Log: not supported by cvs2svn $

 * Revision 1.1.1.1  2001/07/02 17:58:31  simons

 * Initial revision

 *

 * Revision 1.8.2.2  1998/11/05 22:11:35  fritz

 * Changed mail-address.

 *

 * Revision 1.8.2.1  1998/08/22 16:43:04  armin

 * Added silence detection in audio receive mode (AT+VSD).

 *

 * Revision 1.8  1997/03/02 14:29:16  fritz

 * More ttyI related cleanup.

 *

 * Revision 1.7  1997/02/03 22:44:11  fritz

 * Reformatted according CodingStyle

 *

 * Revision 1.6  1996/06/06 14:43:31  fritz

 * Changed to support DTMF decoding on audio playback also.

 *

 * Revision 1.5  1996/06/05 02:24:08  fritz

 * Added DTMF decoder for audio mode.

 *

 * Revision 1.4  1996/05/17 03:48:01  fritz

 * Removed some test statements.

 * Added revision string.

 *

 * Revision 1.3  1996/05/10 08:48:11  fritz

 * Corrected adpcm bugs.

 *

 * Revision 1.2  1996/04/30 09:31:17  fritz

 * General rewrite.

 *

 * Revision 1.1.1.1  1996/04/28 12:25:40  fritz

 * Taken under CVS control

 *

 */

#define __NO_VERSION__

#include <linux/module.h>

#include <linux/isdn.h>

#include "isdn_audio.h"

#include "isdn_common.h"

char *isdn_audio_revision = "$Revision: 1.1.1.1 $";

/*

 * Misc. lookup-tables.

 */

/* ulaw -> signed 16-bit */

static short isdn_audio_ulaw_to_s16[] =

{

        0x8284, 0x8684, 0x8a84, 0x8e84, 0x9284, 0x9684, 0x9a84, 0x9e84,

        0xa284, 0xa684, 0xaa84, 0xae84, 0xb284, 0xb684, 0xba84, 0xbe84,

        0xc184, 0xc384, 0xc584, 0xc784, 0xc984, 0xcb84, 0xcd84, 0xcf84,

        0xd184, 0xd384, 0xd584, 0xd784, 0xd984, 0xdb84, 0xdd84, 0xdf84,

        0xe104, 0xe204, 0xe304, 0xe404, 0xe504, 0xe604, 0xe704, 0xe804,

        0xe904, 0xea04, 0xeb04, 0xec04, 0xed04, 0xee04, 0xef04, 0xf004,

        0xf0c4, 0xf144, 0xf1c4, 0xf244, 0xf2c4, 0xf344, 0xf3c4, 0xf444,

        0xf4c4, 0xf544, 0xf5c4, 0xf644, 0xf6c4, 0xf744, 0xf7c4, 0xf844,

        0xf8a4, 0xf8e4, 0xf924, 0xf964, 0xf9a4, 0xf9e4, 0xfa24, 0xfa64,

        0xfaa4, 0xfae4, 0xfb24, 0xfb64, 0xfba4, 0xfbe4, 0xfc24, 0xfc64,

        0xfc94, 0xfcb4, 0xfcd4, 0xfcf4, 0xfd14, 0xfd34, 0xfd54, 0xfd74,

        0xfd94, 0xfdb4, 0xfdd4, 0xfdf4, 0xfe14, 0xfe34, 0xfe54, 0xfe74,

        0xfe8c, 0xfe9c, 0xfeac, 0xfebc, 0xfecc, 0xfedc, 0xfeec, 0xfefc,

        0xff0c, 0xff1c, 0xff2c, 0xff3c, 0xff4c, 0xff5c, 0xff6c, 0xff7c,

        0xff88, 0xff90, 0xff98, 0xffa0, 0xffa8, 0xffb0, 0xffb8, 0xffc0,

        0xffc8, 0xffd0, 0xffd8, 0xffe0, 0xffe8, 0xfff0, 0xfff8, 0x0000,

        0x7d7c, 0x797c, 0x757c, 0x717c, 0x6d7c, 0x697c, 0x657c, 0x617c,

        0x5d7c, 0x597c, 0x557c, 0x517c, 0x4d7c, 0x497c, 0x457c, 0x417c,

        0x3e7c, 0x3c7c, 0x3a7c, 0x387c, 0x367c, 0x347c, 0x327c, 0x307c,

        0x2e7c, 0x2c7c, 0x2a7c, 0x287c, 0x267c, 0x247c, 0x227c, 0x207c,

        0x1efc, 0x1dfc, 0x1cfc, 0x1bfc, 0x1afc, 0x19fc, 0x18fc, 0x17fc,

        0x16fc, 0x15fc, 0x14fc, 0x13fc, 0x12fc, 0x11fc, 0x10fc, 0x0ffc,

        0x0f3c, 0x0ebc, 0x0e3c, 0x0dbc, 0x0d3c, 0x0cbc, 0x0c3c, 0x0bbc,

        0x0b3c, 0x0abc, 0x0a3c, 0x09bc, 0x093c, 0x08bc, 0x083c, 0x07bc,

        0x075c, 0x071c, 0x06dc, 0x069c, 0x065c, 0x061c, 0x05dc, 0x059c,

        0x055c, 0x051c, 0x04dc, 0x049c, 0x045c, 0x041c, 0x03dc, 0x039c,

        0x036c, 0x034c, 0x032c, 0x030c, 0x02ec, 0x02cc, 0x02ac, 0x028c,

        0x026c, 0x024c, 0x022c, 0x020c, 0x01ec, 0x01cc, 0x01ac, 0x018c,

        0x0174, 0x0164, 0x0154, 0x0144, 0x0134, 0x0124, 0x0114, 0x0104,

        0x00f4, 0x00e4, 0x00d4, 0x00c4, 0x00b4, 0x00a4, 0x0094, 0x0084,

        0x0078, 0x0070, 0x0068, 0x0060, 0x0058, 0x0050, 0x0048, 0x0040,

        0x0038, 0x0030, 0x0028, 0x0020, 0x0018, 0x0010, 0x0008, 0x0000

};

/* alaw -> signed 16-bit */

static short isdn_audio_alaw_to_s16[] =

{

        0x13fc, 0xec04, 0x0144, 0xfebc, 0x517c, 0xae84, 0x051c, 0xfae4,

        0x0a3c, 0xf5c4, 0x0048, 0xffb8, 0x287c, 0xd784, 0x028c, 0xfd74,

        0x1bfc, 0xe404, 0x01cc, 0xfe34, 0x717c, 0x8e84, 0x071c, 0xf8e4,

        0x0e3c, 0xf1c4, 0x00c4, 0xff3c, 0x387c, 0xc784, 0x039c, 0xfc64,

        0x0ffc, 0xf004, 0x0104, 0xfefc, 0x417c, 0xbe84, 0x041c, 0xfbe4,

        0x083c, 0xf7c4, 0x0008, 0xfff8, 0x207c, 0xdf84, 0x020c, 0xfdf4,

        0x17fc, 0xe804, 0x018c, 0xfe74, 0x617c, 0x9e84, 0x061c, 0xf9e4,

        0x0c3c, 0xf3c4, 0x0084, 0xff7c, 0x307c, 0xcf84, 0x030c, 0xfcf4,

        0x15fc, 0xea04, 0x0164, 0xfe9c, 0x597c, 0xa684, 0x059c, 0xfa64,

        0x0b3c, 0xf4c4, 0x0068, 0xff98, 0x2c7c, 0xd384, 0x02cc, 0xfd34,

        0x1dfc, 0xe204, 0x01ec, 0xfe14, 0x797c, 0x8684, 0x07bc, 0xf844,

        0x0f3c, 0xf0c4, 0x00e4, 0xff1c, 0x3c7c, 0xc384, 0x03dc, 0xfc24,

        0x11fc, 0xee04, 0x0124, 0xfedc, 0x497c, 0xb684, 0x049c, 0xfb64,

        0x093c, 0xf6c4, 0x0028, 0xffd8, 0x247c, 0xdb84, 0x024c, 0xfdb4,

        0x19fc, 0xe604, 0x01ac, 0xfe54, 0x697c, 0x9684, 0x069c, 0xf964,

        0x0d3c, 0xf2c4, 0x00a4, 0xff5c, 0x347c, 0xcb84, 0x034c, 0xfcb4,

        0x12fc, 0xed04, 0x0134, 0xfecc, 0x4d7c, 0xb284, 0x04dc, 0xfb24,

        0x09bc, 0xf644, 0x0038, 0xffc8, 0x267c, 0xd984, 0x026c, 0xfd94,

        0x1afc, 0xe504, 0x01ac, 0xfe54, 0x6d7c, 0x9284, 0x06dc, 0xf924,

        0x0dbc, 0xf244, 0x00b4, 0xff4c, 0x367c, 0xc984, 0x036c, 0xfc94,

        0x0f3c, 0xf0c4, 0x00f4, 0xff0c, 0x3e7c, 0xc184, 0x03dc, 0xfc24,

        0x07bc, 0xf844, 0x0008, 0xfff8, 0x1efc, 0xe104, 0x01ec, 0xfe14,

        0x16fc, 0xe904, 0x0174, 0xfe8c, 0x5d7c, 0xa284, 0x05dc, 0xfa24,

        0x0bbc, 0xf444, 0x0078, 0xff88, 0x2e7c, 0xd184, 0x02ec, 0xfd14,

        0x14fc, 0xeb04, 0x0154, 0xfeac, 0x557c, 0xaa84, 0x055c, 0xfaa4,

        0x0abc, 0xf544, 0x0058, 0xffa8, 0x2a7c, 0xd584, 0x02ac, 0xfd54,

        0x1cfc, 0xe304, 0x01cc, 0xfe34, 0x757c, 0x8a84, 0x075c, 0xf8a4,

        0x0ebc, 0xf144, 0x00d4, 0xff2c, 0x3a7c, 0xc584, 0x039c, 0xfc64,

        0x10fc, 0xef04, 0x0114, 0xfeec, 0x457c, 0xba84, 0x045c, 0xfba4,

        0x08bc, 0xf744, 0x0018, 0xffe8, 0x227c, 0xdd84, 0x022c, 0xfdd4,

        0x18fc, 0xe704, 0x018c, 0xfe74, 0x657c, 0x9a84, 0x065c, 0xf9a4,

        0x0cbc, 0xf344, 0x0094, 0xff6c, 0x327c, 0xcd84, 0x032c, 0xfcd4

};

/* alaw -> ulaw */

static char isdn_audio_alaw_to_ulaw[] =

{

        0xab, 0x2b, 0xe3, 0x63, 0x8b, 0x0b, 0xc9, 0x49,

        0xba, 0x3a, 0xf6, 0x76, 0x9b, 0x1b, 0xd7, 0x57,

        0xa3, 0x23, 0xdd, 0x5d, 0x83, 0x03, 0xc1, 0x41,

        0xb2, 0x32, 0xeb, 0x6b, 0x93, 0x13, 0xcf, 0x4f,

        0xaf, 0x2f, 0xe7, 0x67, 0x8f, 0x0f, 0xcd, 0x4d,

        0xbe, 0x3e, 0xfe, 0x7e, 0x9f, 0x1f, 0xdb, 0x5b,

        0xa7, 0x27, 0xdf, 0x5f, 0x87, 0x07, 0xc5, 0x45,

        0xb6, 0x36, 0xef, 0x6f, 0x97, 0x17, 0xd3, 0x53,

        0xa9, 0x29, 0xe1, 0x61, 0x89, 0x09, 0xc7, 0x47,

        0xb8, 0x38, 0xf2, 0x72, 0x99, 0x19, 0xd5, 0x55,

        0xa1, 0x21, 0xdc, 0x5c, 0x81, 0x01, 0xbf, 0x3f,

        0xb0, 0x30, 0xe9, 0x69, 0x91, 0x11, 0xce, 0x4e,

        0xad, 0x2d, 0xe5, 0x65, 0x8d, 0x0d, 0xcb, 0x4b,

        0xbc, 0x3c, 0xfa, 0x7a, 0x9d, 0x1d, 0xd9, 0x59,

        0xa5, 0x25, 0xde, 0x5e, 0x85, 0x05, 0xc3, 0x43,

        0xb4, 0x34, 0xed, 0x6d, 0x95, 0x15, 0xd1, 0x51,

        0xac, 0x2c, 0xe4, 0x64, 0x8c, 0x0c, 0xca, 0x4a,

        0xbb, 0x3b, 0xf8, 0x78, 0x9c, 0x1c, 0xd8, 0x58,

        0xa4, 0x24, 0xde, 0x5e, 0x84, 0x04, 0xc2, 0x42,

        0xb3, 0x33, 0xec, 0x6c, 0x94, 0x14, 0xd0, 0x50,

        0xb0, 0x30, 0xe8, 0x68, 0x90, 0x10, 0xce, 0x4e,

        0xbf, 0x3f, 0xfe, 0x7e, 0xa0, 0x20, 0xdc, 0x5c,

        0xa8, 0x28, 0xe0, 0x60, 0x88, 0x08, 0xc6, 0x46,

        0xb7, 0x37, 0xf0, 0x70, 0x98, 0x18, 0xd4, 0x54,

        0xaa, 0x2a, 0xe2, 0x62, 0x8a, 0x0a, 0xc8, 0x48,

        0xb9, 0x39, 0xf4, 0x74, 0x9a, 0x1a, 0xd6, 0x56,

        0xa2, 0x22, 0xdd, 0x5d, 0x82, 0x02, 0xc0, 0x40,

        0xb1, 0x31, 0xea, 0x6a, 0x92, 0x12, 0xcf, 0x4f,

        0xae, 0x2e, 0xe6, 0x66, 0x8e, 0x0e, 0xcc, 0x4c,

        0xbd, 0x3d, 0xfc, 0x7c, 0x9e, 0x1e, 0xda, 0x5a,

        0xa6, 0x26, 0xdf, 0x5f, 0x86, 0x06, 0xc4, 0x44,

        0xb5, 0x35, 0xee, 0x6e, 0x96, 0x16, 0xd2, 0x52

};

/* ulaw -> alaw */

static char isdn_audio_ulaw_to_alaw[] =

{

        0xab, 0x55, 0xd5, 0x15, 0x95, 0x75, 0xf5, 0x35,

        0xb5, 0x45, 0xc5, 0x05, 0x85, 0x65, 0xe5, 0x25,

        0xa5, 0x5d, 0xdd, 0x1d, 0x9d, 0x7d, 0xfd, 0x3d,

        0xbd, 0x4d, 0xcd, 0x0d, 0x8d, 0x6d, 0xed, 0x2d,

        0xad, 0x51, 0xd1, 0x11, 0x91, 0x71, 0xf1, 0x31,

        0xb1, 0x41, 0xc1, 0x01, 0x81, 0x61, 0xe1, 0x21,

        0x59, 0xd9, 0x19, 0x99, 0x79, 0xf9, 0x39, 0xb9,

        0x49, 0xc9, 0x09, 0x89, 0x69, 0xe9, 0x29, 0xa9,

        0xd7, 0x17, 0x97, 0x77, 0xf7, 0x37, 0xb7, 0x47,

        0xc7, 0x07, 0x87, 0x67, 0xe7, 0x27, 0xa7, 0xdf,

        0x9f, 0x7f, 0xff, 0x3f, 0xbf, 0x4f, 0xcf, 0x0f,

        0x8f, 0x6f, 0xef, 0x2f, 0x53, 0x13, 0x73, 0x33,

        0xb3, 0x43, 0xc3, 0x03, 0x83, 0x63, 0xe3, 0x23,

        0xa3, 0x5b, 0xdb, 0x1b, 0x9b, 0x7b, 0xfb, 0x3b,

        0xbb, 0xbb, 0x4b, 0x4b, 0xcb, 0xcb, 0x0b, 0x0b,

        0x8b, 0x8b, 0x6b, 0x6b, 0xeb, 0xeb, 0x2b, 0x2b,

        0xab, 0x54, 0xd4, 0x14, 0x94, 0x74, 0xf4, 0x34,

        0xb4, 0x44, 0xc4, 0x04, 0x84, 0x64, 0xe4, 0x24,

        0xa4, 0x5c, 0xdc, 0x1c, 0x9c, 0x7c, 0xfc, 0x3c,

        0xbc, 0x4c, 0xcc, 0x0c, 0x8c, 0x6c, 0xec, 0x2c,

        0xac, 0x50, 0xd0, 0x10, 0x90, 0x70, 0xf0, 0x30,

        0xb0, 0x40, 0xc0, 0x00, 0x80, 0x60, 0xe0, 0x20,

        0x58, 0xd8, 0x18, 0x98, 0x78, 0xf8, 0x38, 0xb8,

        0x48, 0xc8, 0x08, 0x88, 0x68, 0xe8, 0x28, 0xa8,

        0xd6, 0x16, 0x96, 0x76, 0xf6, 0x36, 0xb6, 0x46,

        0xc6, 0x06, 0x86, 0x66, 0xe6, 0x26, 0xa6, 0xde,

        0x9e, 0x7e, 0xfe, 0x3e, 0xbe, 0x4e, 0xce, 0x0e,

        0x8e, 0x6e, 0xee, 0x2e, 0x52, 0x12, 0x72, 0x32,

        0xb2, 0x42, 0xc2, 0x02, 0x82, 0x62, 0xe2, 0x22,

        0xa2, 0x5a, 0xda, 0x1a, 0x9a, 0x7a, 0xfa, 0x3a,

        0xba, 0xba, 0x4a, 0x4a, 0xca, 0xca, 0x0a, 0x0a,

        0x8a, 0x8a, 0x6a, 0x6a, 0xea, 0xea, 0x2a, 0x2a

};

#define NCOEFF           16     /* number of frequencies to be analyzed       */

#define DTMF_TRESH    50000     /* above this is dtmf                         */

#define SILENCE_TRESH   100     /* below this is silence                      */

#define H2_TRESH      10000     /* 2nd harmonic                               */

#define AMP_BITS          9     /* bits per sample, reduced to avoid overflow */

#define LOGRP             0

#define HIGRP             1

typedef struct {

        int grp;                /* low/high group     */

        int k;                  /* k                  */

        int k2;                 /* k fuer 2. harmonic */

} dtmf_t;

/* For DTMF recognition:

 * 2 * cos(2 * PI * k / N) precalculated for all k

 */

static int cos2pik[NCOEFF] =

{

        55812, 29528, 53603, 24032, 51193, 14443, 48590, 6517,

        38113, -21204, 33057, -32186, 25889, -45081, 18332, -55279

};

static dtmf_t dtmf_tones[8] =

{

        {LOGRP, 0, 1},          /*  697 Hz */

        {LOGRP, 2, 3},          /*  770 Hz */

        {LOGRP, 4, 5},          /*  852 Hz */

        {LOGRP, 6, 7},          /*  941 Hz */

        {HIGRP, 8, 9},          /* 1209 Hz */

        {HIGRP, 10, 11},        /* 1336 Hz */

        {HIGRP, 12, 13},        /* 1477 Hz */

        {HIGRP, 14, 15}         /* 1633 Hz */

};

static char dtmf_matrix[4][4] =

{

        {'1', '2', '3', 'A'},

        {'4', '5', '6', 'B'},

        {'7', '8', '9', 'C'},

        {'*', '0', '#', 'D'}

};

#if ((CPU == 386) || (CPU == 486) || (CPU == 586))

static inline void

isdn_audio_tlookup(const void *table, void *buff, unsigned long n)

{

        __asm__("cld\n"

                "1:\tlodsb\n\t"

                "xlatb\n\t"

                "stosb\n\t"

                "loop 1b\n\t"

      : :  "b"((long) table), "c"(n), "D"((long) buff), "S"((long) buff)

      :        "bx", "cx", "di", "si", "ax");

}

#else

static inline void

isdn_audio_tlookup(const char *table, char *buff, unsigned long n)

{

        while (n--)

                *buff++ = table[*buff];

}

#endif

void

isdn_audio_ulaw2alaw(unsigned char *buff, unsigned long len)

{

        isdn_audio_tlookup(isdn_audio_ulaw_to_alaw, buff, len);

}

void

isdn_audio_alaw2ulaw(unsigned char *buff, unsigned long len)

{

        isdn_audio_tlookup(isdn_audio_alaw_to_ulaw, buff, len);

}

/*

 * linear <-> adpcm conversion stuff

 * Most parts from the mgetty-package.

 * (C) by Gert Doering and Klaus Weidner

 * Used by permission of Gert Doering

 */

#define ZEROTRAP                /* turn on the trap as per the MIL-STD */

#undef ZEROTRAP

#define BIAS 0x84               /* define the add-in bias for 16 bit samples */

#define CLIP 32635

static unsigned char

isdn_audio_linear2ulaw(int sample)

{

        static int exp_lut[256] =

        {

                0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,

                4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,

                5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,

                5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,

                6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,

                6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,

                6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,

                6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

                7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7

        };

        int sign,

         exponent,

         mantissa;

        unsigned char ulawbyte;

        /* Get the sample into sign-magnitude. */

        sign = (sample >> 8) & 0x80;    /* set aside the sign  */

        if (sign != 0)

                sample = -sample;       /* get magnitude       */

        if (sample > CLIP)

                sample = CLIP;  /* clip the magnitude  */

        /* Convert from 16 bit linear to ulaw. */

        sample = sample + BIAS;

        exponent = exp_lut[(sample >> 7) & 0xFF];

        mantissa = (sample >> (exponent + 3)) & 0x0F;

        ulawbyte = ~(sign | (exponent << 4) | mantissa);

#ifdef ZEROTRAP

        /* optional CCITT trap */

        if (ulawbyte == 0)

                ulawbyte = 0x02;

#endif

        return (ulawbyte);

}

static int Mx[3][8] =

{

        {0x3800, 0x5600, 0, 0, 0, 0, 0, 0},

        {0x399a, 0x3a9f, 0x4d14, 0x6607, 0, 0, 0, 0},

        {0x3556, 0x3556, 0x399A, 0x3A9F, 0x4200, 0x4D14, 0x6607, 0x6607},

};

static int bitmask[9] =

{

        0, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff

};

static int

isdn_audio_get_bits(adpcm_state * s, unsigned char **in, int *len)

{

        while (s->nleft < s->nbits) {

                int d = *((*in)++);

                (*len)--;

                s->word = (s->word << 8) | d;

                s->nleft += 8;

        }

        s->nleft -= s->nbits;

        return (s->word >> s->nleft) & bitmask[s->nbits];

}

static void

isdn_audio_put_bits(int data, int nbits, adpcm_state * s,

                    unsigned char **out, int *len)

{

        s->word = (s->word << nbits) | (data & bitmask[nbits]);

        s->nleft += nbits;

        while (s->nleft >= 8) {

                int d = (s->word >> (s->nleft - 8));

                *(out[0]++) = d & 255;

                (*len)++;

                s->nleft -= 8;

        }

}

adpcm_state *

isdn_audio_adpcm_init(adpcm_state * s, int nbits)

{

        if (!s)

                s = (adpcm_state *) kmalloc(sizeof(adpcm_state), GFP_ATOMIC);

        if (s) {

                s->a = 0;

                s->d = 5;

                s->word = 0;

                s->nleft = 0;

                s->nbits = nbits;

        }

        return s;

}

dtmf_state *

isdn_audio_dtmf_init(dtmf_state * s)

{

        if (!s)

                s = (dtmf_state *) kmalloc(sizeof(dtmf_state), GFP_ATOMIC);

        if (s) {

                s->idx = 0;

                s->last = ' ';

        }

        return s;

}

/*

 * Decompression of adpcm data to a/u-law

 *

 */

int

isdn_audio_adpcm2xlaw(adpcm_state * s, int fmt, unsigned char *in,

                      unsigned char *out, int len)

{

        int a = s->a;

        int d = s->d;

        int nbits = s->nbits;

        int olen = 0;

        while (len) {

                int e = isdn_audio_get_bits(s, &in, &len);

                int sign;

                if (nbits == 4 && e == 0)

                        d = 4;

                sign = (e >> (nbits - 1)) ? -1 : 1;

                e &= bitmask[nbits - 1];

                a += sign * ((e << 1) + 1) * d >> 1;

                if (d & 1)

                        a++;