codec_a_mu.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief codec_a_mu.c - translate between alaw and ulaw directly
 *
 * \ingroup codecs
 */

#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#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 "asterisk/ulaw.h"
#include "asterisk/utils.h"

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

AST_MUTEX_DEFINE_STATIC(localuser_lock);
static int localusecnt = 0;

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

static unsigned char mu2a[256];
static unsigned char a2mu[256];

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

#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 laws.
 */

struct ulaw_encoder_pvt
{
	struct ast_frame f;
	char offset[AST_FRIENDLY_OFFSET];	/* Space to build offset */
	unsigned char outbuf[BUFFER_SIZE];	/* Encoded ulaw values */
	int tail;
};

static struct ast_translator_pvt *alawtoulaw_new(void)
{
	struct ulaw_encoder_pvt *tmp;
	
	if ((tmp = ast_calloc(1, sizeof(*tmp)))) {
		tmp->tail = 0;
		localusecnt++;
		ast_update_use_count();
	}

	return (struct ast_translator_pvt *)tmp;
}

static struct ast_translator_pvt *ulawtoalaw_new(void)
{
	struct alaw_encoder_pvt *tmp;
	
	if ((tmp = ast_calloc(1, sizeof(*tmp)))) {
		localusecnt++;
		ast_update_use_count();
		tmp->tail = 0;
	}

	return (struct ast_translator_pvt *)tmp;
}

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

	if ((tmp->tail + f->datalen) > 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] = a2mu[b[x]];

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

static struct ast_frame *alawtoulaw_frameout(struct ast_translator_pvt *pvt)
{
	struct ulaw_encoder_pvt *tmp = (struct ulaw_encoder_pvt *)pvt;

	if (!tmp->tail)
		return NULL;

	tmp->f.frametype = AST_FRAME_VOICE;
	tmp->f.subclass = AST_FORMAT_ULAW;
	tmp->f.datalen = tmp->tail;
	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;
}

static int ulawtoalaw_framein(struct ast_translator_pvt *pvt, struct ast_frame *f)
{
	struct alaw_encoder_pvt *tmp = (struct alaw_encoder_pvt *)pvt;
	int x;
	unsigned char *s;
	if (tmp->tail + f->datalen >= sizeof(tmp->outbuf)) {
		ast_log(LOG_WARNING, "Out of buffer space\n");
		return -1;
	}
	s = f->data;
	for (x=0;x<f->datalen;x++) 
		tmp->outbuf[x+tmp->tail] = mu2a[s[x]];
	tmp->tail += f->datalen;
	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 *ulawtoalaw_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 *alawtoulaw_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;
}

static struct ast_frame *ulawtoalaw_sample(void)
{
	static struct ast_frame f;
	f.frametype = AST_FRAME_VOICE;
	f.subclass = AST_FORMAT_ULAW;
	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;
}

/*
 * 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 alawtoulaw = {
	"alawtoulaw",
	AST_FORMAT_ALAW,
	AST_FORMAT_ULAW,
	alawtoulaw_new,
	alawtoulaw_framein,
	alawtoulaw_frameout,
	alaw_destroy,
	/* NULL */
	alawtoulaw_sample
};

/*
 * The complete translator for LinToalaw.
 */

static struct ast_translator ulawtoalaw = {
	"ulawtoalaw",
	AST_FORMAT_ULAW,
	AST_FORMAT_ALAW,
	ulawtoalaw_new,
	ulawtoalaw_framein,
	ulawtoalaw_frameout,
	alaw_destroy,
	/* NULL */
	ulawtoalaw_sample
};

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

int load_module(void)
{
	int res;
	int x;
	for (x=0;x<256;x++) {
		mu2a[x] = AST_LIN2A(AST_MULAW(x));
		a2mu[x] = AST_LIN2MU(AST_ALAW(x));
	}
	res = ast_register_translator(&alawtoulaw);
	if (!res)
		res = ast_register_translator(&ulawtoalaw);
	else
		ast_unregister_translator(&alawtoulaw);
	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;
}