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49 lines
877 B
C
49 lines
877 B
C
/*
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* crc32.c
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*
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* Created on: Aug 6, 2018
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* Author: peter
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*/
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/*
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* Adapted from here:
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* https://stackoverflow.com/questions/36584265/using-cortex-m4-hardware-support-to-compute-crc32
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*/
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#include "crc32.h"
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#include <stm32l4xx_hal.h>
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extern CRC_HandleTypeDef hcrc;
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uint32_t crc32(void *data, uint32_t bytes)
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{
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uint32_t *p32 = data ;
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uint32_t crc, crc_reg ;
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__HAL_CRC_DR_RESET(&hcrc);
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while (bytes >= 4)
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{
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hcrc.Instance->DR = __RBIT(*p32++) ;
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bytes -= 4 ;
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}
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crc_reg = hcrc.Instance->DR ;
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crc = __RBIT(crc_reg) ;
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if (bytes > 0)
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{
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uint32_t bits = 8 * bytes ;
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uint32_t xtra = 32 - bits ;
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uint32_t mask = (1 << bits) - 1 ;
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hcrc.Instance->DR = crc_reg ;
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hcrc.Instance->DR = __RBIT((*p32 & mask) ^ crc) >> xtra ;
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crc = (crc >> bits) ^ __RBIT(hcrc.Instance->DR);
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}
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return ~(crc) ;
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}
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