1 d7094239 2003-11-23 devnull #include	<u.h>
 2 d7094239 2003-11-23 devnull #include	<libc.h>
 3 d7094239 2003-11-23 devnull #include	<ip.h>
 4 d7094239 2003-11-23 devnull 
 5 d7094239 2003-11-23 devnull static	short	endian	= 1;
 6 d7094239 2003-11-23 devnull static	uchar*	aendian	= (uchar*)&endian;
 7 d7094239 2003-11-23 devnull #define	LITTLE	*aendian
 8 d7094239 2003-11-23 devnull 
 9 d7094239 2003-11-23 devnull ushort
10 d7094239 2003-11-23 devnull ptclbsum(uchar *addr, int len)
11 d7094239 2003-11-23 devnull {
12 d7094239 2003-11-23 devnull 	ulong losum, hisum, mdsum, x;
13 d7094239 2003-11-23 devnull 	ulong t1, t2;
14 d7094239 2003-11-23 devnull 
15 d7094239 2003-11-23 devnull 	losum = 0;
16 d7094239 2003-11-23 devnull 	hisum = 0;
17 d7094239 2003-11-23 devnull 	mdsum = 0;
18 d7094239 2003-11-23 devnull 
19 d7094239 2003-11-23 devnull 	x = 0;
20 d7094239 2003-11-23 devnull 	if((ulong)addr & 1) {
21 d7094239 2003-11-23 devnull 		if(len) {
22 d7094239 2003-11-23 devnull 			hisum += addr[0];
23 d7094239 2003-11-23 devnull 			len--;
24 d7094239 2003-11-23 devnull 			addr++;
25 d7094239 2003-11-23 devnull 		}
26 d7094239 2003-11-23 devnull 		x = 1;
27 d7094239 2003-11-23 devnull 	}
28 d7094239 2003-11-23 devnull 	while(len >= 16) {
29 d7094239 2003-11-23 devnull 		t1 = *(ushort*)(addr+0);
30 d7094239 2003-11-23 devnull 		t2 = *(ushort*)(addr+2);	mdsum += t1;
31 d7094239 2003-11-23 devnull 		t1 = *(ushort*)(addr+4);	mdsum += t2;
32 d7094239 2003-11-23 devnull 		t2 = *(ushort*)(addr+6);	mdsum += t1;
33 d7094239 2003-11-23 devnull 		t1 = *(ushort*)(addr+8);	mdsum += t2;
34 d7094239 2003-11-23 devnull 		t2 = *(ushort*)(addr+10);	mdsum += t1;
35 d7094239 2003-11-23 devnull 		t1 = *(ushort*)(addr+12);	mdsum += t2;
36 d7094239 2003-11-23 devnull 		t2 = *(ushort*)(addr+14);	mdsum += t1;
37 d7094239 2003-11-23 devnull 		mdsum += t2;
38 d7094239 2003-11-23 devnull 		len -= 16;
39 d7094239 2003-11-23 devnull 		addr += 16;
40 d7094239 2003-11-23 devnull 	}
41 d7094239 2003-11-23 devnull 	while(len >= 2) {
42 d7094239 2003-11-23 devnull 		mdsum += *(ushort*)addr;
43 d7094239 2003-11-23 devnull 		len -= 2;
44 d7094239 2003-11-23 devnull 		addr += 2;
45 d7094239 2003-11-23 devnull 	}
46 d7094239 2003-11-23 devnull 	if(x) {
47 d7094239 2003-11-23 devnull 		if(len)
48 d7094239 2003-11-23 devnull 			losum += addr[0];
49 d7094239 2003-11-23 devnull 		if(LITTLE)
50 d7094239 2003-11-23 devnull 			losum += mdsum;
51 d7094239 2003-11-23 devnull 		else
52 d7094239 2003-11-23 devnull 			hisum += mdsum;
53 d7094239 2003-11-23 devnull 	} else {
54 d7094239 2003-11-23 devnull 		if(len)
55 d7094239 2003-11-23 devnull 			hisum += addr[0];
56 d7094239 2003-11-23 devnull 		if(LITTLE)
57 d7094239 2003-11-23 devnull 			hisum += mdsum;
58 d7094239 2003-11-23 devnull 		else
59 d7094239 2003-11-23 devnull 			losum += mdsum;
60 d7094239 2003-11-23 devnull 	}
61 d7094239 2003-11-23 devnull 
62 d7094239 2003-11-23 devnull 	losum += hisum >> 8;
63 d7094239 2003-11-23 devnull 	losum += (hisum & 0xff) << 8;
64 d7094239 2003-11-23 devnull 	while(hisum = losum>>16)
65 d7094239 2003-11-23 devnull 		losum = hisum + (losum & 0xffff);
66 d7094239 2003-11-23 devnull 
67 d7094239 2003-11-23 devnull 	return losum & 0xffff;
68 d7094239 2003-11-23 devnull }