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/*
* arch/s390/lib/checksum.c
* S390 fast network checksum routines
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Ulrich Hild (first version),
* Martin Schwidefsky (schwidefsky@de.ibm.com),
* Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
*
* This file contains network checksum routines
*/
#include <linux/string.h>
#include <linux/types.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>
#include <asm/checksum.h>
/*
* computes a partial checksum, e.g. for TCP/UDP fragments
*/
unsigned int
csum_partial (const unsigned char *buff, int len, unsigned int sum)
{
/*
* Experiments with ethernet and slip connections show that buff
* is aligned on either a 2-byte or 4-byte boundary.
*/
__asm__ __volatile__ (
" lr 2,%1\n" /* address in gpr 2 */
" lr 3,%2\n" /* length in gpr 3 */
"0: cksm %0,2\n" /* do checksum on longs */
" jo 0b\n"
: "+&d" (sum)
: "d" (buff), "d" (len)
: "cc", "2", "3" );
return sum;
}
/*
* Fold a partial checksum without adding pseudo headers
*/
unsigned short csum_fold(unsigned int sum)
{
__asm__ __volatile__ (
" sr 3,3\n" /* %0 = H*65536 + L */
" lr 2,%0\n" /* %0 = H L, R2/R3 = H L / 0 0 */
" srdl 2,16\n" /* %0 = H L, R2/R3 = 0 H / L 0 */
" alr 2,3\n" /* %0 = H L, R2/R3 = L H / L 0 */
" alr %0,2\n" /* %0 = H+L+C L+H */
" srl %0,16\n" /* %0 = H+L+C */
: "+d" (sum) : : "cc", "2", "3");
return ((unsigned short) ~sum);
}
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