/*
* arch/arm/include/asm/checksum.h
*
* IP checksum routines
*
* Copyright (C) Original authors of ../asm-i386/checksum.h
* Copyright (C) 1996-1999 Russell King
*/
#ifndef __ASM_ARM_CHECKSUM_H
#define __ASM_ARM_CHECKSUM_H

#include <linux/in6.h>

/*
* computes the checksum of a memory block at buff, length len,
* and adds in "sum" (32-bit)
*
* returns a 32-bit number suitable for feeding into itself
* or csum_tcpudp_magic
*
* this function must be called with even lengths, except
* for the last fragment, which may be odd
*
* it's best to have buff aligned on a 32-bit boundary
*/
__wsum csum_partial(const void *buff, int len, __wsum sum);

/*
* the same as csum_partial, but copies from src while it
* checksums, and handles user-space pointer exceptions correctly, when needed.
*
* here even more important to align src and dst on a 32-bit (or even
* better 64-bit) boundary
*/

__wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum);

__wsum
csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *err_ptr);

/*
* Fold a partial checksum without adding pseudo headers
*/
static inline __sum16 csum_fold(__wsum sum)
{
__asm__(
"add %0, %1, %1, ror #16 @ csum_fold"
: "=r" (sum)
: "r" (sum)
: "cc");
return (__force __sum16)(~(__force u32)sum >> 16);
}

/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*/
static inline __sum16
ip_fast_csum(const void *iph, unsigned int ihl)
{
unsigned int tmp1;
__wsum sum;

__asm__ __volatile__(
"ldr %0, [%1], #4 @ ip_fast_csum \n\
ldr %3, [%1], #4 \n\
sub %2, %2, #5 \n\
adds %0, %0, %3 \n\
ldr %3, [%1], #4 \n\
adcs %0, %0, %3 \n\
ldr %3, [%1], #4 \n\
1: adcs %0, %0, %3 \n\
ldr %3, [%1], #4 \n\
tst %2, #15 @ do this carefully \n\
subne %2, %2, #1 @ without destroying \n\
bne 1b @ the carry flag \n\
adcs %0, %0, %3 \n\
adc %0, %0, #0"
: "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
: "1" (iph), "2" (ihl)
: "cc", "memory");
return csum_fold(sum);
}

static inline __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
unsigned short proto, __wsum sum)
{
__asm__(
"adds %0, %1, %2 @ csum_tcpudp_nofold \n\
adcs %0, %0, %3 \n"
#ifdef __ARMEB__
"adcs %0, %0, %4 \n"
#else
"adcs %0, %0, %4, lsl #8 \n"
#endif
"adcs %0, %0, %5 \n\
adc %0, %0, #0"
: "=&r"(sum)
: "r" (sum), "r" (daddr), "r" (saddr), "r" (len), "Ir" (htons(proto))
: "cc");
return sum;
}
/*
* computes the checksum of the TCP/UDP pseudo-header
* returns a 16-bit checksum, already complemented
*/
static inline __sum16
csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
unsigned short proto, __wsum sum)
{
return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
}


/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
static inline __sum16
ip_compute_csum(const void *buff, int len)
{
return csum_fold(csum_partial(buff, len, 0));
}

#define _HAVE_ARCH_IPV6_CSUM
extern __wsum
__csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
__be32 proto, __wsum sum);

static inline __sum16
csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __u32 len,
unsigned short proto, __wsum sum)
{
return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
htonl(proto), sum));
}
#endif