/*  * 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>#include <auth.h>#include "ppp.h" static	ushort	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;} ushortptclcsum(Block *bp, int offset, int len){	uchar *addr;	ulong losum, hisum;	ushort csum;	int odd, blen, x; 	/* Correct to front of data area */	while(bp != nil && offset && offset >= BLEN(bp)) {		offset -= BLEN(bp);		bp = bp->next;	}	if(bp == nil)		return 0; 	addr = bp->rptr + offset;	blen = BLEN(bp) - offset; 	if(bp->next == nil) {		if(blen < len)			len = blen;		return ~ptclbsum(addr, len) & 0xffff;	} 	losum = 0;	hisum = 0; 	odd = 0;	while(len) {		x = blen;		if(len < x)			x = len; 		csum = ptclbsum(addr, x);		if(odd)			hisum += csum;		else			losum += csum;		odd = (odd+x) & 1;		len -= x; 		bp = bp->next;		if(bp == nil)			break;		blen = BLEN(bp);		addr = bp->rptr;	} 	losum += hisum>>8;	losum += (hisum&0xff)<<8;	while((csum = losum>>16) != 0)		losum = csum + (losum & 0xffff); 	return ~losum & 0xffff;} ushortipcsum(uchar *addr){	int len;	ulong sum; 	sum = 0;	len = (addr[0]&0xf)<<2; 	while(len > 0) {		sum += (addr[0]<<8) | addr[1] ;		len -= 2;		addr += 2;	} 	sum = (sum & 0xffff) + (sum >> 16);	sum = (sum & 0xffff) + (sum >> 16); 	return (sum^0xffff);}