/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include	<u.h>#include	<libc.h>#include	<ip.h> static	short	endian	= 1;static	uchar*	aendian	= (uchar*)&endian;#define	LITTLE	*aendian ushortptclbsum(uchar *addr, int len){	ulong losum, hisum, mdsum, x;	ulong t1, t2; 	losum = 0;	hisum = 0;	mdsum = 0; 	x = 0;	if((uintptr)addr & 1) {		if(len) {			hisum += addr[0];			len--;			addr++;		}		x = 1;	}	while(len >= 16) {		t1 = *(ushort*)(addr+0);		t2 = *(ushort*)(addr+2);	mdsum += t1;		t1 = *(ushort*)(addr+4);	mdsum += t2;		t2 = *(ushort*)(addr+6);	mdsum += t1;		t1 = *(ushort*)(addr+8);	mdsum += t2;		t2 = *(ushort*)(addr+10);	mdsum += t1;		t1 = *(ushort*)(addr+12);	mdsum += t2;		t2 = *(ushort*)(addr+14);	mdsum += t1;		mdsum += t2;		len -= 16;		addr += 16;	}	while(len >= 2) {		mdsum += *(ushort*)addr;		len -= 2;		addr += 2;	}	if(x) {		if(len)			losum += addr[0];		if(LITTLE)			losum += mdsum;		else			hisum += mdsum;	} else {		if(len)			hisum += addr[0];		if(LITTLE)			hisum += mdsum;		else			losum += mdsum;	} 	losum += hisum >> 8;	losum += (hisum & 0xff) << 8;	while(hisum = losum>>16)		losum = hisum + (losum & 0xffff); 	return losum & 0xffff;}