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betaflight/src/main/common/crc.c
2017-11-03 23:51:25 +00:00

111 lines
2.7 KiB
C

/*
* This file is part of Cleanflight.
*
* Cleanflight is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Cleanflight is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Cleanflight. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdint.h>
#include "streambuf.h"
uint16_t crc16_ccitt(uint16_t crc, unsigned char a)
{
crc ^= (uint16_t)a << 8;
for (int ii = 0; ii < 8; ++ii) {
if (crc & 0x8000) {
crc = (crc << 1) ^ 0x1021;
} else {
crc = crc << 1;
}
}
return crc;
}
uint16_t crc16_ccitt_update(uint16_t crc, const void *data, uint32_t length)
{
const uint8_t *p = (const uint8_t *)data;
const uint8_t *pend = p + length;
for (; p != pend; p++) {
crc = crc16_ccitt(crc, *p);
}
return crc;
}
void crc16_ccitt_sbuf_append(sbuf_t *dst, uint8_t *start)
{
uint16_t crc = 0;
const uint8_t * const end = sbufPtr(dst);
for (const uint8_t *ptr = start; ptr < end; ++ptr) {
crc = crc16_ccitt(crc, *ptr);
}
sbufWriteU16(dst, crc);
}
uint8_t crc8_dvb_s2(uint8_t crc, unsigned char a)
{
crc ^= a;
for (int ii = 0; ii < 8; ++ii) {
if (crc & 0x80) {
crc = (crc << 1) ^ 0xD5;
} else {
crc = crc << 1;
}
}
return crc;
}
uint8_t crc8_dvb_s2_update(uint8_t crc, const void *data, uint32_t length)
{
const uint8_t *p = (const uint8_t *)data;
const uint8_t *pend = p + length;
for (; p != pend; p++) {
crc = crc8_dvb_s2(crc, *p);
}
return crc;
}
void crc8_dvb_s2_sbuf_append(sbuf_t *dst, uint8_t *start)
{
uint8_t crc = 0;
const uint8_t * const end = dst->ptr;
for (const uint8_t *ptr = start; ptr < end; ++ptr) {
crc = crc8_dvb_s2(crc, *ptr);
}
sbufWriteU8(dst, crc);
}
uint8_t crc8_xor_update(uint8_t crc, const void *data, uint32_t length)
{
const uint8_t *p = (const uint8_t *)data;
const uint8_t *pend = p + length;
for (; p != pend; p++) {
crc ^= *p;
}
return crc;
}
void crc8_xor_sbuf_append(sbuf_t *dst, uint8_t *start)
{
uint8_t crc = 0;
const uint8_t *end = dst->ptr;
for (uint8_t *ptr = start; ptr < end; ++ptr) {
crc ^= *ptr;
}
sbufWriteU8(dst, crc);
}