| Christina Quast | 8be71e4 | 2014-12-02 13:06:01 +0100 | [diff] [blame] | 1 | /* ----------------------------------------------------------------------------
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| 2 | * ATMEL Microcontroller Software Support
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| 3 | * ----------------------------------------------------------------------------
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| 4 | * Copyright (c) 2009, Atmel Corporation
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| 5 | *
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| 6 | * All rights reserved.
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| 7 | *
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| 8 | * Redistribution and use in source and binary forms, with or without
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| 9 | * modification, are permitted provided that the following conditions are met:
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| 10 | *
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| 11 | * - Redistributions of source code must retain the above copyright notice,
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| 12 | * this list of conditions and the disclaimer below.
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| 13 | *
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| 14 | * Atmel's name may not be used to endorse or promote products derived from
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| 15 | * this software without specific prior written permission.
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| 16 | *
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| 17 | * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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| 19 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
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| 20 | * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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| 22 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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| 23 | * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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| 24 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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| 25 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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| 26 | * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | * ----------------------------------------------------------------------------
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| 28 | */
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| 29 |
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| 30 | /** \addtogroup crccu_module Working with CRCCU
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| 31 | * The CRCCU driver provides the interface to configure and use the CRCCU
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| 32 | * peripheral.
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| 33 | *
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| 34 | * It performs a CRC computation on a Memory Area. CRC computation is performed
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| 35 | * from the LSB to MSB bit. Three different polynomials are available:
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| 36 | * CCIT802.3, CASTAGNOLI and CCIT16.
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| 37 | *
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| 38 | * To computes CRC of a buffer, the user has to follow these few steps:
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| 39 | * <ul>
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| 40 | * <li>Reset initial CRC by setting RESET bit in CRCCU_CRC_CR,</li>
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| 41 | * <li>Configure CRC descriptor and working mode,</li>
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| 42 | * <li>Start to compute CRC by setting DMAEN in CRCCU_DMA_EN,</li>
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| 43 | * <li>Get CRC value in CRCCU_CRC_SR.</li>
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| 44 | * </ul>
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| 45 | *
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| 46 | * For more accurate information, please look at the CRCCU section of the
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| 47 | * Datasheet.
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| 48 | *
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| 49 | * Related files :\n
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| 50 | * \ref crccu.c\n
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| 51 | * \ref crccu.h.\n
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| 52 | */
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| 53 | /*@{*/
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| 54 | /*@}*/
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| 55 |
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| 56 | /**
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| 57 | * \file
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| 58 | *
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| 59 | * Implementation of Cyclic Redundancy Check Calculation Unit (CRCCU).
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| 60 | *
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| 61 | */
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| 62 |
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| 63 | /*----------------------------------------------------------------------------
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| 64 | * Headers
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| 65 | *----------------------------------------------------------------------------*/
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| 66 | #include "chip.h"
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| 67 |
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| 68 | /*----------------------------------------------------------------------------
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| 69 | * Definitions
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| 70 | *----------------------------------------------------------------------------*/
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| 71 | #define CRCCU_TIMEOUT 0xFFFFFFFF
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| 72 |
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| 73 | /*----------------------------------------------------------------------------
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| 74 | * Exported functions
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| 75 | *----------------------------------------------------------------------------*/
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| 76 | /**
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| 77 | * \brief Reset initial CRC to 0xFFFFFFFF.
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| 78 | */
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| 79 | extern void CRCCU_ResetCrcValue( Crccu* pCrccu )
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| 80 | {
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| 81 | pCrccu->CRCCU_CR = CRCCU_CR_RESET;
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| 82 | }
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| 83 |
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| 84 | /**
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| 85 | * \brief Configure the CRCCU.
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| 86 | *
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| 87 | * \param dscrAddr CRC decscriptor address.
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| 88 | * \param mode CRC work mode
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| 89 | */
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| 90 | extern void CRCCU_Configure( Crccu* pCrccu, uint32_t dwDscrAddr, uint32_t dwMode )
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| 91 | {
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| 92 | pCrccu->CRCCU_DSCR = dwDscrAddr ;
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| 93 | pCrccu->CRCCU_MR = dwMode ;
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| 94 | }
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| 95 |
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| 96 | /**
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| 97 | * \brief Start to compute the CRC of a buffer.
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| 98 | *
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| 99 | * \return The CRC of the buffer.
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| 100 | */
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| 101 | extern uint32_t CRCCU_ComputeCrc( Crccu* pCrccu )
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| 102 | {
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| 103 | uint32_t dwTimeout = 0 ;
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| 104 |
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| 105 | pCrccu->CRCCU_DMA_EN = CRCCU_DMA_EN_DMAEN ;
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| 106 |
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| 107 | while ( ((pCrccu->CRCCU_DMA_SR & CRCCU_DMA_SR_DMASR) == CRCCU_DMA_SR_DMASR) &&
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| 108 | (dwTimeout++ < CRCCU_TIMEOUT) ) ;
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| 109 |
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| 110 | return (pCrccu->CRCCU_SR) ;
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| 111 | }
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| 112 |
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