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/* Copyright (c) 2017, Linaro Limited
* All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <odp/api/chksum.h>
#include <odp/api/std_types.h>
/* Simple implementation of ones complement sum.
* Based on RFC1071 and its errata.
*/
uint16_t odp_chksum_ones_comp16(const void *p, uint32_t len)
{
uint32_t sum = 0;
const uint16_t *data = p;
while (len > 1) {
sum += *data++;
len -= 2;
}
/* Add left-over byte, if any */
if (len > 0) {
uint16_t left_over = 0;
*(uint8_t *)&left_over = *(const uint8_t *)data;
sum += left_over;
}
/* Fold 32-bit sum to 16 bits */
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
return sum;
}
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