![](/media/cache/profiles/2012_sf_avc_095.jpg.50x50_q85.jpg)
Code for autonomous rover for Sparkfun AVC. DataBus won 3rd in 2012 and the same code was used on Troubled Child, a 1986 Jeep Grand Wagoneer to win 1st in 2014.
Dependencies: mbed Watchdog SDFileSystem DigoleSerialDisp
MAVlink/include/checksum.h
- Committer:
- shimniok
- Date:
- 2018-11-30
- Revision:
- 25:bb5356402687
- Parent:
- 0:a6a169de725f
File content as of revision 25:bb5356402687:
#ifdef __cplusplus extern "C" { #endif #ifndef _CHECKSUM_H_ #define _CHECKSUM_H_ #include "inttypes.h" /** * * CALCULATE THE CHECKSUM * */ #define X25_INIT_CRC 0xffff #define X25_VALIDATE_CRC 0xf0b8 /** * @brief Accumulate the X.25 CRC by adding one char at a time. * * The checksum function adds the hash of one char at a time to the * 16 bit checksum (uint16_t). * * @param data new char to hash * @param crcAccum the already accumulated checksum **/ static inline void crc_accumulate(uint8_t data, uint16_t *crcAccum) { /*Accumulate one byte of data into the CRC*/ uint8_t tmp; tmp=data ^ (uint8_t)(*crcAccum &0xff); tmp^= (tmp<<4); *crcAccum = (*crcAccum>>8) ^ (tmp<<8) ^ (tmp <<3) ^ (tmp>>4); } /** * @brief Initiliaze the buffer for the X.25 CRC * * @param crcAccum the 16 bit X.25 CRC */ static inline void crc_init(uint16_t* crcAccum) { *crcAccum = X25_INIT_CRC; } /** * @brief Calculates the X.25 checksum on a byte buffer * * @param pBuffer buffer containing the byte array to hash * @param length length of the byte array * @return the checksum over the buffer bytes **/ static inline uint16_t crc_calculate(uint8_t* pBuffer, int length) { // For a "message" of length bytes contained in the unsigned char array // pointed to by pBuffer, calculate the CRC // crcCalculate(unsigned char* pBuffer, int length, unsigned short* checkConst) < not needed uint16_t crcTmp; //uint16_t tmp; uint8_t* pTmp; int i; pTmp=pBuffer; /* init crcTmp */ crc_init(&crcTmp); for (i = 0; i < length; i++){ crc_accumulate(*pTmp++, &crcTmp); } /* This is currently not needed, as only the checksum over payload should be computed tmp = crcTmp; crcAccumulate((unsigned char)(~crcTmp & 0xff),&tmp); crcAccumulate((unsigned char)((~crcTmp>>8)&0xff),&tmp); *checkConst = tmp; */ return(crcTmp); } #endif /* _CHECKSUM_H_ */ #ifdef __cplusplus } #endif