codecs/codec_a_mu.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2005, Digium, Inc.
   5  *
   6  * Mark Spencer <markster@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  *
  21  * \brief codec_a_mu.c - translate between alaw and ulaw directly
  22  *
  23  * \ingroup codecs
  24  */
  25
  26 #include "asterisk.h"
  27
  28 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  29
  30 #include <fcntl.h>
  31 #include <netinet/in.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <unistd.h>
  36
  37 #include "asterisk/lock.h"
  38 #include "asterisk/logger.h"
  39 #include "asterisk/module.h"
  40 #include "asterisk/translate.h"
  41 #include "asterisk/channel.h"
  42 #include "asterisk/alaw.h"
  43 #include "asterisk/ulaw.h"
  44 #include "asterisk/utils.h"
  45
  46 #define BUFFER_SAMPLES   8000   /* size for the translation buffers */
  47
  48 static unsigned char mu2a[256];
  49 static unsigned char a2mu[256];
  50
  51 /* Sample frame data (Mu data is okay) */
  52
  53 #include "ulaw_slin_ex.h"
  54
  55 /*! \brief convert frame data and store into the buffer */
  56 static int alawtoulaw_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
  57 {
  58         int x = f->samples;
  59         unsigned char *src = f->data;
  60         unsigned char *dst = (unsigned char *)pvt->outbuf + pvt->samples;
  61
  62         pvt->samples += x;
  63         pvt->datalen += x;
  64
  65         while (x--)
  66                 *dst++ = a2mu[*src++];
  67
  68         return 0;
  69 }
  70
  71 /*! \brief convert frame data and store into the buffer */
  72 static int ulawtoalaw_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
  73 {
  74         int x = f->samples;
  75         unsigned char *src = f->data;
  76         unsigned char *dst = (unsigned char *)pvt->outbuf + pvt->samples;
  77
  78         pvt->samples += x;
  79         pvt->datalen += x;
  80
  81         while (x--)
  82                 *dst++ = mu2a[*src++];
  83
  84         return 0;
  85 }
  86
  87 /*
  88  * alawToLin_Sample. Just random data, somehow...
  89  */
  90 static struct ast_frame *alawtoulaw_sample(void)
  91 {
  92         static struct ast_frame f;
  93         f.frametype = AST_FRAME_VOICE;
  94         f.subclass = AST_FORMAT_ALAW;
  95         f.datalen = sizeof(ulaw_slin_ex);
  96         f.samples = sizeof(ulaw_slin_ex);
  97         f.mallocd = 0;
  98         f.offset = 0;
  99         f.src = __PRETTY_FUNCTION__;
 100         f.data = ulaw_slin_ex; /* XXX what ? */
 101         return &f;
 102 }
 103
 104 static struct ast_frame *ulawtoalaw_sample(void)
 105 {
 106         static struct ast_frame f;
 107         f.frametype = AST_FRAME_VOICE;
 108         f.subclass = AST_FORMAT_ULAW;
 109         f.datalen = sizeof(ulaw_slin_ex);
 110         f.samples = sizeof(ulaw_slin_ex);
 111         f.mallocd = 0;
 112         f.offset = 0;
 113         f.src = __PRETTY_FUNCTION__;
 114         f.data = ulaw_slin_ex;
 115         return &f;
 116 }
 117
 118 static struct ast_translator alawtoulaw = {
 119         .name = "alawtoulaw",
 120         .srcfmt = AST_FORMAT_ALAW,
 121         .dstfmt = AST_FORMAT_ULAW,
 122         .framein = alawtoulaw_framein,
 123         .sample = alawtoulaw_sample,
 124         .buffer_samples = BUFFER_SAMPLES,
 125         .buf_size = BUFFER_SAMPLES,
 126 };
 127
 128 static struct ast_translator ulawtoalaw = {
 129         .name = "ulawtoalaw",
 130         .srcfmt = AST_FORMAT_ULAW,
 131         .dstfmt = AST_FORMAT_ALAW,
 132         .framein = ulawtoalaw_framein,
 133         .sample = ulawtoalaw_sample,
 134         .buffer_samples = BUFFER_SAMPLES,
 135         .buf_size = BUFFER_SAMPLES,
 136 };
 137
 138 /*! \brief standard module glue */
 139
 140 static int unload_module(void)
 141 {
 142         int res;
 143
 144         res = ast_unregister_translator(&ulawtoalaw);
 145         res |= ast_unregister_translator(&alawtoulaw);
 146
 147         return res;
 148 }
 149
 150 static int load_module(void)
 151 {
 152         int res;
 153         int x;
 154
 155         for (x=0;x<256;x++) {
 156                 mu2a[x] = AST_LIN2A(AST_MULAW(x));
 157                 a2mu[x] = AST_LIN2MU(AST_ALAW(x));
 158         }
 159         res = ast_register_translator(&alawtoulaw);
 160         if (!res)
 161                 res = ast_register_translator(&ulawtoalaw);
 162         else
 163                 ast_unregister_translator(&alawtoulaw);
 164
 165         return res;
 166 }
 167
 168 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "A-law and Mulaw direct Coder/Decoder");