39 lines
702 B
C
39 lines
702 B
C
#include "crc.h"
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/** \file
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\brief crc16 routine
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*/
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#ifdef __AVR__
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#include <util/crc16.h>
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#else
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// Equivalent to avr-libc's _crc16_update.
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uint16_t _crc16_update(uint16_t crc, uint8_t a) {
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int i;
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crc ^= a;
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for (i = 0; i < 8; ++i) {
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if (crc & 1)
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crc = (crc >> 1) ^ 0xA001;
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else
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crc = (crc >> 1);
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}
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return crc;
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}
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#endif
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/** block-at-once CRC16 calculator
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\param *data data to find crc16 for
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\param len length of data
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\return uint16 crc16 of passed data
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uses avr-libc's optimised crc16 routine
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*/
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uint16_t crc_block(void *data, uint16_t len) {
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uint16_t crc = 0xfeed;
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for (; len; data++, len--) {
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crc = _crc16_update(crc, *((uint8_t *) data));
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}
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return crc;
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}
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