83 lines
2.9 KiB
C
83 lines
2.9 KiB
C
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/**
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* \file
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*
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* \brief This file controls the software FIFO management.
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*
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* These functions manages FIFOs thanks to simple a API. The FIFO can
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* be 100% full thanks to a double-index range implementation. For example,
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* a FIFO of 4 elements can be implemented: the FIFO can really hold up to 4
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* elements.
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* This is particularly well suited for any kind of application needing a lot of
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* small FIFO.
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*
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* Copyright (c) 2010-2015 Atmel Corporation. All rights reserved.
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*
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* \asf_license_start
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*
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* \page License
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3. The name of Atmel may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* 4. This software may only be redistributed and used in connection with an
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* Atmel microcontroller product.
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*
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* THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
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* EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* \asf_license_stop
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*
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*/
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/*
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* Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
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*/
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#include "fifo.h"
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int fifo_init(fifo_desc_t *fifo_desc, void *buffer, uint8_t size)
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{
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// Check the size parameter. It must be not null...
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Assert (size);
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// ... must be a 2-power ...
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Assert (!(size & (size - 1)));
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// ... and must fit in a uint8_t. Since the read and write indexes are using a
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// double-index range implementation, the max FIFO size is thus 128 items.
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Assert (size <= 128);
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// Fifo starts empty.
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fifo_desc->read_index = 0;
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fifo_desc->write_index = 0;
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// Save the size parameter.
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fifo_desc->size = size;
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// Create a mask to speed up the FIFO management (index swapping).
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fifo_desc->mask = (2 * (uint16_t)size) - 1;
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// Save the buffer pointer.
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fifo_desc->buffer.u8ptr = buffer;
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return FIFO_OK;
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}
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