Emaxx Navigation Group / mavlink_emaxx

Mavlink Messages for Emaxx Nav Board

Dependents:   Madpulse_Speed_Control_temp Madpulse_Speed_Control_Students

checksum.h@0:bb2cacd02294, 2017-01-20 (annotated)

Committer:
jdawkins
Date:
Fri Jan 20 13:20:58 2017 +0000
Revision:
0:bb2cacd02294
Initial Commit of Mavlink Messages for Emaxx Board custom messages for decawave ranging and bno055;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
jdawkins 0:bb2cacd02294 1 #ifdef __cplusplus
jdawkins 0:bb2cacd02294 2 extern "C" {
jdawkins 0:bb2cacd02294 3 #endif
jdawkins 0:bb2cacd02294 4
jdawkins 0:bb2cacd02294 5 #ifndef _CHECKSUM_H_
jdawkins 0:bb2cacd02294 6 #define _CHECKSUM_H_
jdawkins 0:bb2cacd02294 7
jdawkins 0:bb2cacd02294 8 // Visual Studio versions before 2010 don't have stdint.h, so we just error out.
jdawkins 0:bb2cacd02294 9 #if (defined _MSC_VER) && (_MSC_VER < 1600)
jdawkins 0:bb2cacd02294 10 #error "The C-MAVLink implementation requires Visual Studio 2010 or greater"
jdawkins 0:bb2cacd02294 11 #endif
jdawkins 0:bb2cacd02294 12
jdawkins 0:bb2cacd02294 13 #include <stdint.h>
jdawkins 0:bb2cacd02294 14
jdawkins 0:bb2cacd02294 15 /**
jdawkins 0:bb2cacd02294 16 *
jdawkins 0:bb2cacd02294 17 * CALCULATE THE CHECKSUM
jdawkins 0:bb2cacd02294 18 *
jdawkins 0:bb2cacd02294 19 */
jdawkins 0:bb2cacd02294 20
jdawkins 0:bb2cacd02294 21 #define X25_INIT_CRC 0xffff
jdawkins 0:bb2cacd02294 22 #define X25_VALIDATE_CRC 0xf0b8
jdawkins 0:bb2cacd02294 23
jdawkins 0:bb2cacd02294 24 #ifndef HAVE_CRC_ACCUMULATE
jdawkins 0:bb2cacd02294 25 /**
jdawkins 0:bb2cacd02294 26 * @brief Accumulate the X.25 CRC by adding one char at a time.
jdawkins 0:bb2cacd02294 27 *
jdawkins 0:bb2cacd02294 28 * The checksum function adds the hash of one char at a time to the
jdawkins 0:bb2cacd02294 29 * 16 bit checksum (uint16_t).
jdawkins 0:bb2cacd02294 30 *
jdawkins 0:bb2cacd02294 31 * @param data new char to hash
jdawkins 0:bb2cacd02294 32 * @param crcAccum the already accumulated checksum
jdawkins 0:bb2cacd02294 33 **/
jdawkins 0:bb2cacd02294 34 static inline void crc_accumulate(uint8_t data, uint16_t *crcAccum)
jdawkins 0:bb2cacd02294 35 {
jdawkins 0:bb2cacd02294 36 /*Accumulate one byte of data into the CRC*/
jdawkins 0:bb2cacd02294 37 uint8_t tmp;
jdawkins 0:bb2cacd02294 38
jdawkins 0:bb2cacd02294 39 tmp = data ^ (uint8_t)(*crcAccum &0xff);
jdawkins 0:bb2cacd02294 40 tmp ^= (tmp<<4);
jdawkins 0:bb2cacd02294 41 *crcAccum = (*crcAccum>>8) ^ (tmp<<8) ^ (tmp <<3) ^ (tmp>>4);
jdawkins 0:bb2cacd02294 42 }
jdawkins 0:bb2cacd02294 43 #endif
jdawkins 0:bb2cacd02294 44
jdawkins 0:bb2cacd02294 45
jdawkins 0:bb2cacd02294 46 /**
jdawkins 0:bb2cacd02294 47 * @brief Initiliaze the buffer for the X.25 CRC
jdawkins 0:bb2cacd02294 48 *
jdawkins 0:bb2cacd02294 49 * @param crcAccum the 16 bit X.25 CRC
jdawkins 0:bb2cacd02294 50 */
jdawkins 0:bb2cacd02294 51 static inline void crc_init(uint16_t* crcAccum)
jdawkins 0:bb2cacd02294 52 {
jdawkins 0:bb2cacd02294 53 *crcAccum = X25_INIT_CRC;
jdawkins 0:bb2cacd02294 54 }
jdawkins 0:bb2cacd02294 55
jdawkins 0:bb2cacd02294 56
jdawkins 0:bb2cacd02294 57 /**
jdawkins 0:bb2cacd02294 58 * @brief Calculates the X.25 checksum on a byte buffer
jdawkins 0:bb2cacd02294 59 *
jdawkins 0:bb2cacd02294 60 * @param pBuffer buffer containing the byte array to hash
jdawkins 0:bb2cacd02294 61 * @param length length of the byte array
jdawkins 0:bb2cacd02294 62 * @return the checksum over the buffer bytes
jdawkins 0:bb2cacd02294 63 **/
jdawkins 0:bb2cacd02294 64 static inline uint16_t crc_calculate(const uint8_t* pBuffer, uint16_t length)
jdawkins 0:bb2cacd02294 65 {
jdawkins 0:bb2cacd02294 66 uint16_t crcTmp;
jdawkins 0:bb2cacd02294 67 crc_init(&crcTmp);
jdawkins 0:bb2cacd02294 68 while (length--) {
jdawkins 0:bb2cacd02294 69 crc_accumulate(*pBuffer++, &crcTmp);
jdawkins 0:bb2cacd02294 70 }
jdawkins 0:bb2cacd02294 71 return crcTmp;
jdawkins 0:bb2cacd02294 72 }
jdawkins 0:bb2cacd02294 73
jdawkins 0:bb2cacd02294 74
jdawkins 0:bb2cacd02294 75 /**
jdawkins 0:bb2cacd02294 76 * @brief Accumulate the X.25 CRC by adding an array of bytes
jdawkins 0:bb2cacd02294 77 *
jdawkins 0:bb2cacd02294 78 * The checksum function adds the hash of one char at a time to the
jdawkins 0:bb2cacd02294 79 * 16 bit checksum (uint16_t).
jdawkins 0:bb2cacd02294 80 *
jdawkins 0:bb2cacd02294 81 * @param data new bytes to hash
jdawkins 0:bb2cacd02294 82 * @param crcAccum the already accumulated checksum
jdawkins 0:bb2cacd02294 83 **/
jdawkins 0:bb2cacd02294 84 static inline void crc_accumulate_buffer(uint16_t *crcAccum, const char *pBuffer, uint16_t length)
jdawkins 0:bb2cacd02294 85 {
jdawkins 0:bb2cacd02294 86 const uint8_t *p = (const uint8_t *)pBuffer;
jdawkins 0:bb2cacd02294 87 while (length--) {
jdawkins 0:bb2cacd02294 88 crc_accumulate(*p++, crcAccum);
jdawkins 0:bb2cacd02294 89 }
jdawkins 0:bb2cacd02294 90 }
jdawkins 0:bb2cacd02294 91
jdawkins 0:bb2cacd02294 92 #endif /* _CHECKSUM_H_ */
jdawkins 0:bb2cacd02294 93
jdawkins 0:bb2cacd02294 94 #ifdef __cplusplus
jdawkins 0:bb2cacd02294 95 }
jdawkins 0:bb2cacd02294 96 #endif
jdawkins 0:bb2cacd02294 97