MakefileBasedBuild/Atmel/sam3x/sam3x-ek/libraries/usb_device/utils/fifo/enhc_fifo/fifo.c

/*This file is prepared for Doxygen automatic documentation generation.*/
/*! \file ******************************************************************
 *
 * \brief This file controls the software FIFO management.
 *
 * These functions manages FIFOs thanks to simple a API. The FIFO can
 * be 100% full thanks to a double-index range implementation. For example,
 * a FIFO of 4 elements can be implemented: the FIFO can really hold up to 4
 * elements.
 * This is particurly well suited for any kind of application needing a lot of 
 * small FIFO.
 *
 * - Compiler:           IAR EWAVR32 and GNU GCC for AVR32
 * - Supported devices:  All AVR32 devices can be used.
 * - AppNote:
 *
 * \author               Atmel Corporation: http://www.atmel.com \n
 *                       Support and FAQ: http://support.atmel.no/
 *
 ***************************************************************************/

/* Copyright (c) 2010 Atmel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. The name of Atmel may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *
 * 4. This software may only be redistributed and used in connection with an Atmel
 * AVR product.
 *
 * THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
 * EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
 *
 */

#include "compiler.h"
#include "fifo.h"

int fifo_init(fifo_desc_t *fifo_desc, void *buffer, uint16_t size)
{
	uint16_t tmp;

	// Check the size parameter. It must be a 2-power.
	tmp = size >> ctz(size);
	if (tmp != 1) {
		return FIFO_ERROR;
	}

	// Fifo starts empty.
	fifo_desc->rd_id = fifo_desc->wr_id = 0;

	// Save the size parameter.
	fifo_desc->size = size;

	// Save the buffer pointer
	fifo_desc->buffer.u8ptr = buffer;

	return FIFO_OK;
}