/* ----------------------------------------------------------------------------
 *         ATMEL Microcontroller Software Support
 * ----------------------------------------------------------------------------
 * Copyright (c) 2009, 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:
 *
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the disclaimer below.
 *
 * Atmel's name may not be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * DISCLAIMER: 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
 * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
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 */

/** \addtogroup crccu_module Working with CRCCU
 * The CRCCU driver provides the interface to configure and use the CRCCU
 * peripheral.
 *
 * It performs a CRC computation on a Memory Area. CRC computation is performed
 * from the LSB to MSB bit. Three different polynomials are available:
 * CCIT802.3, CASTAGNOLI and CCIT16.
 *
 * To computes CRC of a buffer, the user has to follow these few steps:
 * <ul>
 * <li>Reset initial CRC by setting RESET bit in CRCCU_CRC_CR,</li>
 * <li>Configure CRC descriptor and working mode,</li>
 * <li>Start to compute CRC by setting DMAEN in CRCCU_DMA_EN,</li>
 * <li>Get CRC value in CRCCU_CRC_SR.</li>
 * </ul>
 *
 * For more accurate information, please look at the CRCCU section of the
 * Datasheet.
 *
 * Related files :\n
 * \ref crccu.c\n
 * \ref crccu.h.\n
*/
/*@{*/
/*@}*/

/**
 * \file
 *
 * Implementation of Cyclic Redundancy Check Calculation Unit (CRCCU).
 *
 */

/*----------------------------------------------------------------------------
 *        Headers
 *----------------------------------------------------------------------------*/

#include <stdint.h>
#include "crccu.h"
#include <utility/assert.h>

/*----------------------------------------------------------------------------
 *        Definitions
 *----------------------------------------------------------------------------*/
#define CRCCU_TIMEOUT    0xFFFFFFFF

/*----------------------------------------------------------------------------
 *        Exported functions
 *----------------------------------------------------------------------------*/
/**
 * \brief Reset initial CRC to 0xFFFFFFFF.
 */
void CRCCU_ResetCrcValue(void)
{
    Crccu *pCrccu = CRCCU;

    pCrccu->CRCCU_CR = CRCCU_CR_RESET;
}

/**
 * \brief Configure the CRCCU.
 *
 * \param dscrAddr CRC decscriptor address.
 * \param mode     CRC work mode
 */
void CRCCU_Configure(uint32_t dscrAddr, uint32_t mode)
{
    Crccu *pCrccu = CRCCU;

    pCrccu->CRCCU_DSCR = dscrAddr;
    pCrccu->CRCCU_MR = mode;
}

/**
 * \brief Start to compute the CRC of a buffer.
 *
 * \return The CRC of the buffer.
 */
uint32_t CRCCU_ComputeCrc(void)
{
    Crccu *pCrccu = CRCCU;
    uint32_t timeout = 0;

    pCrccu->CRCCU_DMA_EN = CRCCU_DMA_EN_DMAEN;
    while (((pCrccu->CRCCU_DMA_SR & CRCCU_DMA_SR_DMASR) == CRCCU_DMA_SR_DMASR)
        && (timeout++ < CRCCU_TIMEOUT));

    return (pCrccu->CRCCU_SR);
}

/**
 * \brief Compare the CRC of a buffer is match to reference CRC.
 *
 * \return if 0 CRC is match, else dismatch.
 */
uint32_t CRCCU_CompareCrc(void)
{
    Crccu *pCrccu = CRCCU;

    if ((pCrccu->CRCCU_ISR & CRCCU_ISR_ERRISR) == CRCCU_ISR_ERRISR) {
       return 1;
    } else {
       return 0;
    }
}