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 "asterisk/module.h"
  31 #include "asterisk/translate.h"
  32 #include "asterisk/alaw.h"
  33 #include "asterisk/ulaw.h"
  34 #include "asterisk/utils.h"
  35
  36 #define BUFFER_SAMPLES   8000   /* size for the translation buffers */
  37
  38 static unsigned char mu2a[256];
  39 static unsigned char a2mu[256];
  40
  41 /* Sample frame data (Mu data is okay) */
  42
  43 #include "ulaw_slin_ex.h"
  44
  45 /*! \brief convert frame data and store into the buffer */
  46 static int alawtoulaw_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
  47 {
  48         int x = f->samples;
  49         unsigned char *src = f->data.ptr;
  50         unsigned char *dst = (unsigned char *)pvt->outbuf + pvt->samples;
  51
  52         pvt->samples += x;
  53         pvt->datalen += x;
  54
  55         while (x--)
  56                 *dst++ = a2mu[*src++];
  57
  58         return 0;
  59 }
  60
  61 /*! \brief convert frame data and store into the buffer */
  62 static int ulawtoalaw_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
  63 {
  64         int x = f->samples;
  65         unsigned char *src = f->data.ptr;
  66         unsigned char *dst = (unsigned char *)pvt->outbuf + pvt->samples;
  67
  68         pvt->samples += x;
  69         pvt->datalen += x;
  70
  71         while (x--)
  72                 *dst++ = mu2a[*src++];
  73
  74         return 0;
  75 }
  76
  77 /*
  78  * alawToLin_Sample. Just random data, somehow...
  79  */
  80 static struct ast_frame *alawtoulaw_sample(void)
  81 {
  82         static struct ast_frame f;
  83         f.frametype = AST_FRAME_VOICE;
  84         f.subclass = AST_FORMAT_ALAW;
  85         f.datalen = sizeof(ulaw_slin_ex);
  86         f.samples = sizeof(ulaw_slin_ex);
  87         f.mallocd = 0;
  88         f.offset = 0;
  89         f.src = __PRETTY_FUNCTION__;
  90         f.data.ptr = ulaw_slin_ex; /* XXX what ? */
  91         return &f;
  92 }
  93
  94 static struct ast_frame *ulawtoalaw_sample(void)
  95 {
  96         static struct ast_frame f;
  97         f.frametype = AST_FRAME_VOICE;
  98         f.subclass = AST_FORMAT_ULAW;
  99         f.datalen = sizeof(ulaw_slin_ex);
 100         f.samples = sizeof(ulaw_slin_ex);
 101         f.mallocd = 0;
 102         f.offset = 0;
 103         f.src = __PRETTY_FUNCTION__;
 104         f.data.ptr = ulaw_slin_ex;
 105         return &f;
 106 }
 107
 108 static struct ast_translator alawtoulaw = {
 109         .name = "alawtoulaw",
 110         .srcfmt = AST_FORMAT_ALAW,
 111         .dstfmt = AST_FORMAT_ULAW,
 112         .framein = alawtoulaw_framein,
 113         .sample = alawtoulaw_sample,
 114         .buffer_samples = BUFFER_SAMPLES,
 115         .buf_size = BUFFER_SAMPLES,
 116 };
 117
 118 static struct ast_translator ulawtoalaw = {
 119         .name = "ulawtoalaw",
 120         .srcfmt = AST_FORMAT_ULAW,
 121         .dstfmt = AST_FORMAT_ALAW,
 122         .framein = ulawtoalaw_framein,
 123         .sample = ulawtoalaw_sample,
 124         .buffer_samples = BUFFER_SAMPLES,
 125         .buf_size = BUFFER_SAMPLES,
 126 };
 127
 128 /*! \brief standard module glue */
 129
 130 static int unload_module(void)
 131 {
 132         int res;
 133
 134         res = ast_unregister_translator(&ulawtoalaw);
 135         res |= ast_unregister_translator(&alawtoulaw);
 136
 137         return res;
 138 }
 139
 140 static int load_module(void)
 141 {
 142         int res;
 143         int x;
 144
 145         for (x=0;x<256;x++) {
 146                 mu2a[x] = AST_LIN2A(AST_MULAW(x));
 147                 a2mu[x] = AST_LIN2MU(AST_ALAW(x));
 148         }
 149         res = ast_register_translator(&alawtoulaw);
 150         if (!res)
 151                 res = ast_register_translator(&ulawtoalaw);
 152         else
 153                 ast_unregister_translator(&alawtoulaw);
 154         if (res)
 155                 return AST_MODULE_LOAD_FAILURE;
 156         return AST_MODULE_LOAD_SUCCESS;
 157 }
 158
 159 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "A-law and Mulaw direct Coder/Decoder");