codec_alaw.c

/* codec_alaw.c - translate between signed linear and alaw
 * 
 * Asterisk -- A telephony toolkit for Linux.
 *
 * Copyright (c) 2001 Linux Support Services, Inc.  All rights reserved.
 *
 * Mark Spencer <markster@linux-support.net
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 */

#include <asterisk/lock.h>
#include <asterisk/logger.h>
#include <asterisk/module.h>
#include <asterisk/translate.h>
#include <asterisk/channel.h>
#include <asterisk/alaw.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define BUFFER_SIZE   8096	/* size for the translation buffers */

static ast_mutex_t localuser_lock = AST_MUTEX_INITIALIZER;
static int localusecnt = 0;

static char *tdesc = "A-law Coder/Decoder";

/* Sample frame data (Mu data is okay) */

#include "slin_ulaw_ex.h"
#include "ulaw_slin_ex.h"

/*
 * Private workspace for translating signed linear signals to alaw.
 */

struct alaw_encoder_pvt
{
  struct ast_frame f;
  char offset[AST_FRIENDLY_OFFSET];   /* Space to build offset */
  unsigned char outbuf[BUFFER_SIZE];  /* Encoded alaw, two nibbles to a word */
  int tail;
};

/*
 * Private workspace for translating alaw signals to signed linear.
 */

struct alaw_decoder_pvt
{
  struct ast_frame f;
  char offset[AST_FRIENDLY_OFFSET];	/* Space to build offset */
  short outbuf[BUFFER_SIZE];	/* Decoded signed linear values */
  int tail;
};

/*
 * alawToLin_New
 *  Create a new instance of alaw_decoder_pvt.
 *
 * Results:
 *  Returns a pointer to the new instance.
 *
 * Side effects:
 *  None.
 */

static struct ast_translator_pvt *
alawtolin_new (void)
{
  struct alaw_decoder_pvt *tmp;
  tmp = malloc (sizeof (struct alaw_decoder_pvt));
  if (tmp)
    {
	  memset(tmp, 0, sizeof(*tmp));
      tmp->tail = 0;
      localusecnt++;
      ast_update_use_count ();
    }
  return (struct ast_translator_pvt *) tmp;
}

/*
 * LinToalaw_New
 *  Create a new instance of alaw_encoder_pvt.
 *
 * Results:
 *  Returns a pointer to the new instance.
 *
 * Side effects:
 *  None.
 */

static struct ast_translator_pvt *
lintoalaw_new (void)
{
  struct alaw_encoder_pvt *tmp;
  tmp = malloc (sizeof (struct alaw_encoder_pvt));
  if (tmp)
    {
	  memset(tmp, 0, sizeof(*tmp));
      localusecnt++;
      ast_update_use_count ();
      tmp->tail = 0;
    }
  return (struct ast_translator_pvt *) tmp;
}

/*
 * alawToLin_FrameIn
 *  Fill an input buffer with packed 4-bit alaw values if there is room
 *  left.
 *
 * Results:
 *  Foo
 *
 * Side effects:
 *  tmp->tail is the number of packed values in the buffer.
 */

static int
alawtolin_framein (struct ast_translator_pvt *pvt, struct ast_frame *f)
{
  struct alaw_decoder_pvt *tmp = (struct alaw_decoder_pvt *) pvt;
  int x;
  unsigned char *b;

  if ((tmp->tail + f->datalen) * 2 > sizeof(tmp->outbuf)) {
  	ast_log(LOG_WARNING, "Out of buffer space\n");
	return -1;
  }

  /* Reset ssindex and signal to frame's specified values */
  b = f->data;
  for (x=0;x<f->datalen;x++)
  	tmp->outbuf[tmp->tail + x] = AST_ALAW(b[x]);

  tmp->tail += f->datalen;
  return 0;
}

/*
 * alawToLin_FrameOut
 *  Convert 4-bit alaw encoded signals to 16-bit signed linear.
 *
 * Results:
 *  Converted signals are placed in tmp->f.data, tmp->f.datalen
 *  and tmp->f.samples are calculated.
 *
 * Side effects:
 *  None.
 */

static struct ast_frame *
alawtolin_frameout (struct ast_translator_pvt *pvt)
{
  struct alaw_decoder_pvt *tmp = (struct alaw_decoder_pvt *) pvt;

  if (!tmp->tail)
    return NULL;

  tmp->f.frametype = AST_FRAME_VOICE;
  tmp->f.subclass = AST_FORMAT_SLINEAR;
  tmp->f.datalen = tmp->tail *2;
  tmp->f.samples = tmp->tail;
  tmp->f.mallocd = 0;
  tmp->f.offset = AST_FRIENDLY_OFFSET;
  tmp->f.src = __PRETTY_FUNCTION__;
  tmp->f.data = tmp->outbuf;
  tmp->tail = 0;
  return &tmp->f;
}

/*
 * LinToalaw_FrameIn
 *  Fill an input buffer with 16-bit signed linear PCM values.
 *
 * Results:
 *  None.
 *
 * Side effects:
 *  tmp->tail is number of signal values in the input buffer.
 */

static int
lintoalaw_framein (struct ast_translator_pvt *pvt, struct ast_frame *f)
{
  struct alaw_encoder_pvt *tmp = (struct alaw_encoder_pvt *) pvt;
  int x;
  short *s;
  if (tmp->tail + f->datalen/2 >= sizeof(tmp->outbuf))
    {
      ast_log (LOG_WARNING, "Out of buffer space\n");
      return -1;
    }
  s = f->data;
  for (x=0;x<f->datalen/2;x++) 
  	tmp->outbuf[x+tmp->tail] = AST_LIN2A(s[x]);
  tmp->tail += f->datalen/2;
  return 0;
}

/*
 * LinToalaw_FrameOut
 *  Convert a buffer of raw 16-bit signed linear PCM to a buffer
 *  of 4-bit alaw packed two to a byte (Big Endian).
 *
 * Results:
 *  Foo
 *
 * Side effects:
 *  Leftover inbuf data gets packed, tail gets updated.
 */

static struct ast_frame *
lintoalaw_frameout (struct ast_translator_pvt *pvt)
{
  struct alaw_encoder_pvt *tmp = (struct alaw_encoder_pvt *) pvt;
  
  if (tmp->tail) {
	  tmp->f.frametype = AST_FRAME_VOICE;
	  tmp->f.subclass = AST_FORMAT_ALAW;
	  tmp->f.samples = tmp->tail;
	  tmp->f.mallocd = 0;
	  tmp->f.offset = AST_FRIENDLY_OFFSET;
	  tmp->f.src = __PRETTY_FUNCTION__;
	  tmp->f.data = tmp->outbuf;
	  tmp->f.datalen = tmp->tail;
	  tmp->tail = 0;
	  return &tmp->f;
   } else return NULL;
}


/*
 * alawToLin_Sample
 */

static struct ast_frame *
alawtolin_sample (void)
{
  static struct ast_frame f;
  f.frametype = AST_FRAME_VOICE;
  f.subclass = AST_FORMAT_ALAW;
  f.datalen = sizeof (ulaw_slin_ex);
  f.samples = sizeof(ulaw_slin_ex);
  f.mallocd = 0;
  f.offset = 0;
  f.src = __PRETTY_FUNCTION__;
  f.data = ulaw_slin_ex;
  return &f;
}

/*
 * LinToalaw_Sample
 */

static struct ast_frame *
lintoalaw_sample (void)
{
  static struct ast_frame f;
  f.frametype = AST_FRAME_VOICE;
  f.subclass = AST_FORMAT_SLINEAR;
  f.datalen = sizeof (slin_ulaw_ex);
  /* Assume 8000 Hz */
  f.samples = sizeof (slin_ulaw_ex) / 2;
  f.mallocd = 0;
  f.offset = 0;
  f.src = __PRETTY_FUNCTION__;
  f.data = slin_ulaw_ex;
  return &f;
}

/*
 * alaw_Destroy
 *  Destroys a private workspace.
 *
 * Results:
 *  It's gone!
 *
 * Side effects:
 *  None.
 */

static void
alaw_destroy (struct ast_translator_pvt *pvt)
{
  free (pvt);
  localusecnt--;
  ast_update_use_count ();
}

/*
 * The complete translator for alawToLin.
 */

static struct ast_translator alawtolin = {
  "alawtolin",
  AST_FORMAT_ALAW,
  AST_FORMAT_SLINEAR,
  alawtolin_new,
  alawtolin_framein,
  alawtolin_frameout,
  alaw_destroy,
  /* NULL */
  alawtolin_sample
};

/*
 * The complete translator for LinToalaw.
 */

static struct ast_translator lintoalaw = {
  "lintoalaw",
  AST_FORMAT_SLINEAR,
  AST_FORMAT_ALAW,
  lintoalaw_new,
  lintoalaw_framein,
  lintoalaw_frameout,
  alaw_destroy,
  /* NULL */
  lintoalaw_sample
};

int
unload_module (void)
{
  int res;
  ast_mutex_lock (&localuser_lock);
  res = ast_unregister_translator (&lintoalaw);
  if (!res)
    res = ast_unregister_translator (&alawtolin);
  if (localusecnt)
    res = -1;
  ast_mutex_unlock (&localuser_lock);
  return res;
}

int
load_module (void)
{
  int res;
  res = ast_register_translator (&alawtolin);
  if (!res)
    res = ast_register_translator (&lintoalaw);
  else
    ast_unregister_translator (&alawtolin);
  return res;
}

/*
 * Return a description of this module.
 */

char *
description (void)
{
  return tdesc;
}

int
usecount (void)
{
  int res;
  STANDARD_USECOUNT (res);
  return res;
}

char *
key ()
{
  return ASTERISK_GPL_KEY;
}