Technical information

10/29/2014
Page 67 of 72
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12 Appendix: Example CRC16 C Code
The CRC16 required by Reader to Host packets (see Section 5.2) can be calculated using the following
sample C code. This CRC16 consists of two consecutive bytes, each in range [0,255] most significant byte
first. A CRC16 is calculated on each packet byte, over the entire packet, excluding the prefix and the CRC16
itself.
crc_t crc = 0;
<send firstByte>
crc = crc(crc, firstByte, firstByteSize);
<send secondByte>
crc = crc(crc, secondByte, secondByteSize)
<…>
<send crcHighByte>
<send crcLowByte>
/* crc16.h */
#ifndef crc16_h
#define crc16_h
#include <stdint.h>
#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef uint16_t crc_t;
crc_t crc
( crc_t initialCrc
, const unsigned char* bufPtr
, size_t length
);
#ifdef __cplusplus
} // extern "C"
#endif
#endif
/* crc16.c */
#include <crc16.h>