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/*
* linux/include/asm-arm/checksum.h
*
* IP checksum routines
*
* Copyright (C) Original authors of ../asm-i386/checksum.h
* Copyright (C) 1996,1997,1998 Russell King
*/
#ifndef __ASM_ARM_CHECKSUM_H
#define __ASM_ARM_CHECKSUM_H
#ifndef __ASM_ARM_SEGMENT_H
#include <asm/segment.h>
#endif
/*
* 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
*/
unsigned int csum_partial(const unsigned char * buff, int len, unsigned int 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
*/
extern
unsigned int csum_partial_copy_from_user (const char *src, char *dst, int len, int sum, int *err_ptr);
/*
* This combination is currently not used, but possible:
*/
extern
unsigned int csum_partial_copy_to_user (const char *src, char *dst, int len, int sum, int *err_ptr);
/*
* These are the old (and unsafe) way of doing checksums, a warning message will be
* printed if they are used and an exception occurs.
*
* these functions should go away after some time.
*/
#define csum_partial_copy_fromuser csum_partial_copy
unsigned int csum_partial_copy(const char *src, char *dst, int len, int sum);
/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*
* Converted and optimised for ARM by R. M. King.
*
* Note: the order that the LDM registers are loaded with respect to
* the adc's doesn't matter.
*/
static inline unsigned short ip_fast_csum(unsigned char * iph,
unsigned int ihl) {
unsigned int sum, tmp1;
__asm__ __volatile__("
sub %2, %2, #5
ldr %0, [%1], #4
ldr %3, [%1], #4
adds %0, %0, %3
ldr %3, [%1], #4
adcs %0, %0, %3
ldr %3, [%1], #4
adcs %0, %0, %3
1: ldr %3, [%1], #4
adcs %0, %0, %3
tst %2, #15
subne %2, %2, #1
bne 1b
adc %0, %0, #0
adds %0, %0, %0, lsl #16
addcs %0, %0, #0x10000
mvn %0, %0
mov %0, %0, lsr #16
"
: "=&r" (sum), "=&r" (iph), "=&r" (ihl), "=&r" (tmp1)
: "1" (iph), "2" (ihl));
return(sum);
}
/*
* computes the checksum of the TCP/UDP pseudo-header
* returns a 16-bit checksum, already complemented
*/
static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
unsigned long daddr,
unsigned short len,
unsigned short proto,
unsigned int sum) {
__asm__ __volatile__("
adds %0, %0, %1
adcs %0, %0, %4
adcs %0, %0, %5
adc %0, %0, #0
adds %0, %0, %0, lsl #16
addcs %0, %0, #0x10000
mvn %0, %0
mov %0, %0, lsr #16
"
: "=&r" (sum), "=&r" (saddr)
: "0" (daddr), "1"(saddr), "r"((ntohs(len)<<16)+proto*256), "r"(sum));
return((unsigned short)sum);
}
/*
* Fold a partial checksum without adding pseudo headers
*/
static inline unsigned int csum_fold(unsigned int sum)
{
__asm__ __volatile__("
adds %0, %0, %0, lsl #16
addcs %0, %0, #0x10000
mvn %0, %0
mov %0, %0, lsr #16
"
: "=r" (sum)
: "0" (sum));
return sum;
}
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
static inline unsigned short ip_compute_csum(unsigned char * buff, int len) {
unsigned int sum;
__asm__ __volatile__("
adds %0, %0, %0, lsl #16
addcs %0, %0, #0x10000
mvn %0, %0
mov %0, %0, lsr #16
"
: "=r"(sum)
: "0" (csum_partial(buff, len, 0)));
return(sum);
}
#endif
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