/*
 * Copyright (c) 2014-2016 IBM 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 following disclaimer.
 *  * 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.
 *  * Neither the name of the <organization> nor the
 *    names of its contributors may be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> 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.
 */

#include "hw.h"

void crc32_init (void) {
    RCC->AHBENR |= RCC_AHBENR_CRCEN;
}

unsigned int crc32 (void* ptr, int nwords) {
    unsigned int v;
    unsigned int* data = ptr;
    CRC->CR = CRC_CR_RESET;
    while (nwords-- > 0) {
        v = *data++;
#ifdef __GNUC__
        __asm__("rbit %0, %0" : "=r"(v) : "r"(v));
#else
        v = __rbit(v);
#endif
        CRC->DR = v;
    }
    v = CRC->DR;
#ifdef __GNUC__
    __asm__("rbit %0, %0" : "=r"(v) : "r"(v));
#else
        v = __rbit(v);
#endif
    return ~v;
}

void crc32_shutdown (void) {
    RCC->AHBENR &= ~RCC_AHBENR_CRCEN;
}
