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CHG: Minor code clean up.

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ADD: crc16.c - new crc16_ccitt calc.
This commit is contained in:
iceman1001 2015-01-07 20:40:22 +01:00
commit 23b598ee23
6 changed files with 33 additions and 11 deletions
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23
common/crc16.c
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@ -8,6 +8,7 @@
#include "crc16.h"
unsigned short update_crc16( unsigned short crc, unsigned char c )
{
unsigned short i, v, tcrc = 0;
@ -20,3 +21,25 @@ unsigned short update_crc16( unsigned short crc, unsigned char c )
return ((crc >> 8) ^ tcrc)&0xffff;
}
uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t polynomial) {
if (length == 0)
return (~remainder);
for (int byte = 0; byte < length; ++byte) {
remainder ^= (message[byte] << 8);
for (uint8_t bit = 8; bit > 0; --bit) {
if (remainder & 0x8000) {
remainder = (remainder << 1) ^ polynomial;
} else {
remainder = (remainder << 1);
}
}
}
return remainder;
}
uint16_t crc16_ccitt(uint8_t const *message, int length) {
return crc16(message, length, 0xffff, 0x1021);
}