/*

 * A simple kernel FIFO implementation.

 *

 * Copyright (C) 2004 Stelian Pop <stelian@popies.net>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 *

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "fifo.h"

#include "minmax.h"

struct fifo *fifo_alloc(unsigned int size)

{

	struct fifo *fifo;

	fifo = malloc(sizeof(struct fifo));

	if (!fifo)

		return NULL;

	fifo->buffer = malloc(size);

	fifo->size = size;

	fifo->in = fifo->out = 0;

	return fifo;

}

void fifo_free(struct fifo *fifo)

{

	free(fifo->buffer);

	free(fifo);

}

unsigned int fifo_put(struct fifo *fifo, void *buffer, unsigned int len)

{

	unsigned int l;

	len = min(len, fifo_room(fifo));

	/* first put the data starting from fifo->in to buffer end */

	l = min(len, fifo->size - (fifo->in & (fifo->size - 1)));

	memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l);

	/* then put the rest (if any) at the beginning of the buffer */

	memcpy(fifo->buffer, buffer + l, len - l);

	/*

	 * Ensure that we add the bytes to the fifo -before-

	 * we update the fifo->in index.

	 */

	fifo->in += len;

	return len;

}

unsigned int fifo_get(struct fifo *fifo, void *buf, unsigned int len)

{

	len = min(len, fifo->in - fifo->out);

	if (buf) {

		unsigned int l;

		/*

		 * first get the data from fifo->out until the end of the buffer

		 */

		l = min(len, fifo->size - (fifo->out & (fifo->size - 1)));

		memcpy(buf, fifo->buffer + (fifo->out & (fifo->size - 1)), l);

		/*

		 * then get the rest (if any) from the beginning of the buffer

		 */

		memcpy(buf + l, fifo->buffer, len - l);

	}

	fifo->out += len;

	if (fifo->in == fifo->out)

		fifo->in = fifo->out = 0;

	return len;

}