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AP_Math: added crc_sum8

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for FPort/FPort2
This commit is contained in:
Andrew Tridgell 2020-10-26 17:32:52 +11:00
parent 66596dcf25
commit 747b48d0a8
2 changed files with 16 additions and 0 deletions
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13
libraries/AP_Math/crc.cpp
View File

@ -334,3 +334,16 @@ uint32_t crc_crc24(const uint8_t *bytes, uint16_t len)
}
return crc;
}
// simple 8 bit checksum used by FPort
uint8_t crc_sum8(const uint8_t *p, uint8_t len)
{
uint16_t sum = 0;
for (uint8_t i=0; i<len; i++) {
sum += p[i];
sum += sum >> 8;
sum &= 0xFF;
}
sum = 0xff - ((sum & 0xff) + (sum >> 8));
return sum;
}

3
libraries/AP_Math/crc.h
View File

@ -28,6 +28,9 @@ uint32_t crc_crc32(uint32_t crc, const uint8_t *buf, uint32_t size);
uint32_t crc32_small(uint32_t crc, const uint8_t *buf, uint32_t size);
uint32_t crc_crc24(const uint8_t *bytes, uint16_t len);
// checksum used by SPORT/FPort
uint8_t crc_sum8(const uint8_t *p, uint8_t len);
// Copyright (C) 2010 Swift Navigation Inc.
// Contact: Fergus Noble <fergus@swift-nav.com>
uint16_t crc16_ccitt(const uint8_t *buf, uint32_t len, uint16_t crc);