codec_ulaw.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_ulaw.c - translate between signed linear and ulaw
 * 
 * \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/config.h"
#include "asterisk/options.h"
#include "asterisk/translate.h"
#include "asterisk/channel.h"
#include "asterisk/ulaw.h"

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

AST_MUTEX_DEFINE_STATIC(localuser_lock);
static int localusecnt = 0;

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

static int useplc = 0;

/* Sample frame data */

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

/*!
 * \brief Private workspace for translating signed linear signals to ulaw.
 */

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

/*!
 * \brief Private workspace for translating ulaw signals to signed linear.
 */

struct ulaw_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;
	plc_state_t plc;
};

/*!
 * \brief ulawToLin_New
 *  Create a new instance of ulaw_decoder_pvt.
 *
 * Results:
 *  Returns a pointer to the new instance.
 *
 * Side effects:
 *  None.
 */

static struct ast_translator_pvt *ulawtolin_new(void)
{
	struct ulaw_decoder_pvt *tmp;
	tmp = malloc(sizeof(struct ulaw_decoder_pvt));
	if (tmp) {
		memset(tmp, 0, sizeof(*tmp));
		tmp->tail = 0;
		plc_init(&tmp->plc);
		localusecnt++;
		ast_update_use_count();
	}
	return (struct ast_translator_pvt *)tmp;
}

/*!
 * \brief LinToulaw_New
 *  Create a new instance of ulaw_encoder_pvt.
 *
 * Results:
 *  Returns a pointer to the new instance.
 *
 * Side effects:
 *  None.
 */

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

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

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

	if(f->datalen == 0) { /* perform PLC with nominal framesize of 20ms/160 samples */
		if((tmp->tail + 160) * 2 > sizeof(tmp->outbuf)) {
			ast_log(LOG_WARNING, "Out of buffer space\n");
			return -1;
		}
		if(useplc) {
			plc_fillin(&tmp->plc, tmp->outbuf+tmp->tail, 160);
			tmp->tail += 160;
		}
		return 0;
	}

	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_MULAW(b[x]);

	if(useplc)
		plc_rx(&tmp->plc, tmp->outbuf+tmp->tail, f->datalen);

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

/*!
 * \brief ulawToLin_FrameOut
 *  Convert 4-bit ulaw 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 *ulawtolin_frameout(struct ast_translator_pvt *pvt)
{
	struct ulaw_decoder_pvt *tmp = (struct ulaw_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;
}

/*!
 * \brief LinToulaw_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 lintoulaw_framein(struct ast_translator_pvt *pvt, struct ast_frame *f)
{
	struct ulaw_encoder_pvt *tmp = (struct ulaw_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_LIN2MU(s[x]);
	tmp->tail += f->datalen/2;
	return 0;
}

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

static struct ast_frame *lintoulaw_frameout(struct ast_translator_pvt *pvt)
{
	struct ulaw_encoder_pvt *tmp = (struct ulaw_encoder_pvt *)pvt;
  
	if (tmp->tail) {
		tmp->f.frametype = AST_FRAME_VOICE;
		tmp->f.subclass = AST_FORMAT_ULAW;
		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;
}


/*!
 * \brief ulawToLin_Sample
 */

static struct ast_frame *ulawtolin_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;
}

/*!
 * \brief LinToulaw_Sample
 */

static struct ast_frame *lintoulaw_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;
}

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

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

/*!
 * \brief The complete translator for ulawToLin.
 */

static struct ast_translator ulawtolin = {
	"ulawtolin",
	AST_FORMAT_ULAW,
	AST_FORMAT_SLINEAR,
	ulawtolin_new,
	ulawtolin_framein,
	ulawtolin_frameout,
	ulaw_destroy,
	/* NULL */
	ulawtolin_sample
};

/*!
 * \brief The complete translator for LinToulaw.
 */

static struct ast_translator lintoulaw = {
	"lintoulaw",
	AST_FORMAT_SLINEAR,
	AST_FORMAT_ULAW,
	lintoulaw_new,
	lintoulaw_framein,
	lintoulaw_frameout,
	ulaw_destroy,
	/* NULL */
	lintoulaw_sample
};

static void parse_config(void)
{
	struct ast_config *cfg;
	struct ast_variable *var;
	if ((cfg = ast_config_load("codecs.conf"))) {
		if ((var = ast_variable_browse(cfg, "plc"))) {
			while (var) {
				if (!strcasecmp(var->name, "genericplc")) {
					useplc = ast_true(var->value) ? 1 : 0;
					if (option_verbose > 2)
						ast_verbose(VERBOSE_PREFIX_3 "codec_ulaw: %susing generic PLC\n", useplc ? "" : "not ");
				}
				var = var->next;
			}
		}
		ast_config_destroy(cfg);
	}
}

int reload(void)
{
	parse_config();
	return 0;
}

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

int load_module(void)
{
	int res;
	parse_config();
	res = ast_register_translator(&ulawtolin);
	if (!res)
		res = ast_register_translator(&lintoulaw);
	else
		ast_unregister_translator(&ulawtolin);
	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;
}