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56 lines
1.6 KiB
C
56 lines
1.6 KiB
C
/*
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This software is subject to the license described in the license.txt file included with this software distribution.
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You may not use this file except in compliance with this license.
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Copyright © Dynastream Innovations Inc. 2012
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All rights reserved.
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*/
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#include "crc.h"
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#include "compiler_abstraction.h"
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/**@brief Function for updating the current CRC-16 value for a single byte input.
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*
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* @param[in] current_crc The current calculated CRC-16 value.
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* @param[in] byte The input data byte for the computation.
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*
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* @return The updated CRC-16 value, based on the input supplied.
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*/
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static __INLINE uint16_t crc16_get(uint16_t current_crc, uint8_t byte)
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{
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static const uint16_t crc16_table[16] =
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{
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0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401,
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0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400
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};
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uint16_t temp;
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// Compute checksum of lower four bits of a byte.
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temp = crc16_table[current_crc & 0xF];
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current_crc = (current_crc >> 4u) & 0x0FFFu;
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current_crc = current_crc ^ temp ^ crc16_table[byte & 0xF];
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// Now compute checksum of upper four bits of a byte.
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temp = crc16_table[current_crc & 0xF];
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current_crc = (current_crc >> 4u) & 0x0FFFu;
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current_crc = current_crc ^ temp ^ crc16_table[(byte >> 4u) & 0xF];
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return current_crc;
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}
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uint16_t crc_crc16_update(uint16_t current_crc, const volatile void * p_data, uint32_t size)
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{
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uint8_t * p_block = (uint8_t *)p_data;
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while (size != 0)
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{
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current_crc = crc16_get(current_crc, *p_block);
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p_block++;
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size--;
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}
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return current_crc;
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}
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