lora-car/libopencm3/lib/stm32/common/crc_v2.c

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/** @addtogroup crc_file CRC peripheral API
@ingroup peripheral_apis
@author @htmlonly &copy; @endhtmlonly 2016 Cem Basoglu <cem.basoglu@web.de>
*/
/*
* This file is part of the libopencm3 project.
*
* Copyright (C) 2016 Cem Basoglu <cem.basoglu@web.de>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
/**@{*/
#include <libopencm3/stm32/crc.h>
/*---------------------------------------------------------------------------*/
/** @brief Enable reverse output data.
Enables the reversal of the bit order of the output data.
*/
void crc_reverse_output_enable()
{
CRC_CR |= CRC_CR_REV_OUT;
}
/*---------------------------------------------------------------------------*/
/** @brief Disable reverse output data.
Disables the reversal of the bit order of the output data.
*/
void crc_reverse_output_disable()
{
CRC_CR &= ~CRC_CR_REV_OUT;
}
/*---------------------------------------------------------------------------*/
/** @brief Reverse input data.
Controls the reversal of the bit order of the input data
@param[in] reverse_in Unsigned int32. Reversal bit order @ref crc_rev_in.
*/
void crc_set_reverse_input(uint32_t reverse_in)
{
uint32_t reg32 = CRC_CR;
reg32 = (reg32 & ~CRC_CR_REV_IN) | reverse_in;
CRC_CR = reg32;
}
/*---------------------------------------------------------------------------*/
/** @brief Polynomial size
Set the size of the polynomial.
@param[in] polysize Unsigned int32. Size of polynomial @ref crc_polysize.
*/
void crc_set_polysize(uint32_t polysize)
{
uint32_t reg32 = CRC_CR;
reg32 = (reg32 & ~CRC_CR_POLYSIZE) | polysize;
CRC_CR = reg32;
}
/*---------------------------------------------------------------------------*/
/** @brief Polynomial coefficient
Set the coefficients of the polynomial to be used for CRC calculation.
If the polynomial size is less than 32-bits, the least significant bits
have to be used to program the correct value.
@note To obtain a reliable CRC calculation, any changes to the polynomial
value or size can not be performed during a CRC calculation.
As a result, if a CRC calculation is ongoing, the application must either
reset the crc unit it or perform a CRC_DR read before changing the polynomial.
@note The default polynomial value is the CRC-32 (Ethernet) polynomial: 0x4C11DB7.
@param[in] polynomial Unsigned int32. Polynomial coefficient.
*/
void crc_set_polynomial(uint32_t polynomial)
{
CRC_POL = polynomial;
}
/*---------------------------------------------------------------------------*/
/** @brief CRC Initial value.
Sets the crc initial value.
@param[in] initial Unsigned int32. CRC initial value.
*/
void crc_set_initial(uint32_t initial)
{
CRC_INIT = initial;
}
/**@}*/