blob: 28181c821c2fca880cb1a81245c5cbff717d89f6 [file] [log] [blame]
/*
* Copyright (c) 2017 Intel Corporation.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <sys/crc.h>
u16_t crc16(const u8_t *src, size_t len, u16_t polynomial,
u16_t initial_value, bool pad)
{
u16_t crc = initial_value;
size_t padding = pad ? sizeof(crc) : 0;
size_t i, b;
/* src length + padding (if required) */
for (i = 0; i < len + padding; i++) {
for (b = 0; b < 8; b++) {
u16_t divide = crc & 0x8000UL;
crc = (crc << 1U);
/* choose input bytes or implicit trailing zeros */
if (i < len) {
crc |= !!(src[i] & (0x80U >> b));
}
if (divide != 0U) {
crc = crc ^ polynomial;
}
}
}
return crc;
}
u16_t crc16_ccitt(u16_t seed, const u8_t *src, size_t len)
{
for (; len > 0; len--) {
u8_t e, f;
e = seed ^ *src++;
f = e ^ (e << 4);
seed = (seed >> 8) ^ (f << 8) ^ (f << 3) ^ (f >> 4);
}
return seed;
}
u16_t crc16_itu_t(u16_t seed, const u8_t *src, size_t len)
{
for (; len > 0; len--) {
seed = (seed >> 8U) | (seed << 8U);
seed ^= *src++;
seed ^= (seed & 0xffU) >> 4U;
seed ^= seed << 12U;
seed ^= (seed & 0xffU) << 5U;
}
return seed;
}