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113 lines
3.8 KiB
C
113 lines
3.8 KiB
C
/* ----------------------------------------------------------------------------
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* ATMEL Microcontroller Software Support
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* ----------------------------------------------------------------------------
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* Copyright (c) 2009, Atmel Corporation
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*
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* All rights reserved.
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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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* - Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the disclaimer below.
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*
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* Atmel's name may not be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
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* IMPLIED 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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* DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* ----------------------------------------------------------------------------
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*/
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/** \addtogroup crccu_module Working with CRCCU
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* The CRCCU driver provides the interface to configure and use the CRCCU
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* peripheral.
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*
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* It performs a CRC computation on a Memory Area. CRC computation is performed
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* from the LSB to MSB bit. Three different polynomials are available:
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* CCIT802.3, CASTAGNOLI and CCIT16.
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*
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* To computes CRC of a buffer, the user has to follow these few steps:
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* <ul>
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* <li>Reset initial CRC by setting RESET bit in CRCCU_CRC_CR,</li>
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* <li>Configure CRC descriptor and working mode,</li>
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* <li>Start to compute CRC by setting DMAEN in CRCCU_DMA_EN,</li>
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* <li>Get CRC value in CRCCU_CRC_SR.</li>
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* </ul>
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*
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* For more accurate information, please look at the CRCCU section of the
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* Datasheet.
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*
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* Related files :\n
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* \ref crccu.c\n
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* \ref crccu.h.\n
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*/
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/*@{*/
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/*@}*/
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/**
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* \file
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*
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* Implementation of Cyclic Redundancy Check Calculation Unit (CRCCU).
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*
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*/
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/*----------------------------------------------------------------------------
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* Headers
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*----------------------------------------------------------------------------*/
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#include "chip.h"
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/*----------------------------------------------------------------------------
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* Definitions
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*----------------------------------------------------------------------------*/
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#define CRCCU_TIMEOUT 0xFFFFFFFF
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/*----------------------------------------------------------------------------
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* Exported functions
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*----------------------------------------------------------------------------*/
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/**
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* \brief Reset initial CRC to 0xFFFFFFFF.
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*/
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extern void CRCCU_ResetCrcValue( Crccu* pCrccu )
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{
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pCrccu->CRCCU_CR = CRCCU_CR_RESET;
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}
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/**
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* \brief Configure the CRCCU.
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*
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* \param dscrAddr CRC decscriptor address.
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* \param mode CRC work mode
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*/
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extern void CRCCU_Configure( Crccu* pCrccu, uint32_t dwDscrAddr, uint32_t dwMode )
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{
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pCrccu->CRCCU_DSCR = dwDscrAddr ;
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pCrccu->CRCCU_MR = dwMode ;
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}
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/**
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* \brief Start to compute the CRC of a buffer.
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*
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* \return The CRC of the buffer.
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*/
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extern uint32_t CRCCU_ComputeCrc( Crccu* pCrccu )
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{
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uint32_t dwTimeout = 0 ;
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pCrccu->CRCCU_DMA_EN = CRCCU_DMA_EN_DMAEN ;
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while ( ((pCrccu->CRCCU_DMA_SR & CRCCU_DMA_SR_DMASR) == CRCCU_DMA_SR_DMASR) &&
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(dwTimeout++ < CRCCU_TIMEOUT) ) ;
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return (pCrccu->CRCCU_SR) ;
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}
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