73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
/**
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* \file crc32.c
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* Functions and types for CRC checks.
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*
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* Generated on Mon Feb 21 23:02:07 2011,
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* by pycrc v0.7.1, http://www.tty1.net/pycrc/
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* using the configuration:
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* Width = 32
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* Poly = 0x04c11db7
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* XorIn = 0xffffffff
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* ReflectIn = True
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* XorOut = 0xffffffff
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* ReflectOut = True
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* Algorithm = bit-by-bit-fast
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* Direct = True
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*****************************************************************************/
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#include "crc32.h"
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#include <stdint.h>
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#include <stdlib.h>
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#include <stdbool.h>
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/**
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* Reflect all bits of a \a data word of \a data_len bytes.
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*
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* \param data The data word to be reflected.
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* \param data_len The width of \a data expressed in number of bits.
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* \return The reflected data.
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******************************************************************************/
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uint32_t crc_reflect(uint32_t data, size_t data_len)
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{
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unsigned int i;
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uint32_t ret;
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ret = data & 0x01;
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for (i = 1; i < data_len; i++)
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{
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data >>= 1;
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ret = (ret << 1) | (data & 0x01);
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}
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return ret;
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}
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/**
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* Update the crc value with new data.
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*
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* \param crc The current crc value.
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* \param data Pointer to a buffer of \a data_len bytes.
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* \param data_len Number of bytes in the \a data buffer.
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* \return The updated crc value.
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*****************************************************************************/
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uint32_t crc32_update(uint32_t crc, const unsigned char data)
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{
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unsigned int i;
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uint32_t bit;
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unsigned char c;
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c = data;
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for (i = 0x01; i & 0xff; i <<= 1) {
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bit = crc & 0x80000000;
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if (c & i) {
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bit = !bit;
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}
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crc <<= 1;
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if (bit) {
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crc ^= 0x04c11db7;
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}
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}
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return crc & 0xffffffff;
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}
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