1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * Copyright (C) 2016 ARM Ltd.
5 #ifndef __ASM_CHECKSUM_H
6 #define __ASM_CHECKSUM_H
8 #include <linux/types.h>
10 static inline __sum16 csum_fold(__wsum csum)
12 u32 sum = (__force u32)csum;
13 sum += (sum >> 16) | (sum << 16);
14 return ~(__force __sum16)(sum >> 16);
16 #define csum_fold csum_fold
18 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
22 int n = ihl; /* we want it signed */
24 tmp = *(const __uint128_t *)iph;
27 tmp += ((tmp >> 64) | (tmp << 64));
30 sum += *(const u32 *)iph;
34 sum += ((sum >> 32) | (sum << 32));
35 return csum_fold((__force u32)(sum >> 32));
37 #define ip_fast_csum ip_fast_csum
39 #include <asm-generic/checksum.h>
41 #endif /* __ASM_CHECKSUM_H */