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/**
* \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 particularly well suited for any kind of application needing a lot of
* small FIFO.
*
* Copyright (c) 2010-2015 Atmel Corporation. All rights reserved.
*
* \asf_license_start
*
* \page License
*
* 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 microcontroller 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.
*
* \asf_license_stop
*
*/
/*
* Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
*/
#include "fifo.h"
int fifo_init(fifo_desc_t *fifo_desc, void *buffer, uint8_t size)
{
// Check the size parameter. It must be not null...
Assert (size);
// ... must be a 2-power ...
Assert (!(size & (size - 1)));
// ... and must fit in a uint8_t. Since the read and write indexes are using a
// double-index range implementation, the max FIFO size is thus 128 items.
Assert (size <= 128);
// Fifo starts empty.
fifo_desc->read_index = 0;
fifo_desc->write_index = 0;
// Save the size parameter.
fifo_desc->size = size;
// Create a mask to speed up the FIFO management (index swapping).
fifo_desc->mask = (2 * (uint16_t)size) - 1;
// Save the buffer pointer.
fifo_desc->buffer.u8ptr = buffer;
return FIFO_OK;
}
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