add in the inferno stack.
[akaros.git] / kern / src / net / ptclbsum.c
1 #include        "u.h"
2 #include        "../port/lib.h"
3 #include        "mem.h"
4 #include        "dat.h"
5 #include        "fns.h"
6 #include        "../port/error.h"
7 #include        "ip.h"
8
9 static  short   endian  = 1;
10 static  uchar*  aendian = (uchar*)&endian;
11 #define LITTLE  *aendian
12
13 ushort
14 ptclbsum(uchar *addr, int len)
15 {
16         ulong losum, hisum, mdsum, x;
17         ulong t1, t2;
18
19         losum = 0;
20         hisum = 0;
21         mdsum = 0;
22
23         x = 0;
24         if((ulong)addr & 1) {
25                 if(len) {
26                         hisum += addr[0];
27                         len--;
28                         addr++;
29                 }
30                 x = 1;
31         }
32         while(len >= 16) {
33                 t1 = *(ushort*)(addr+0);
34                 t2 = *(ushort*)(addr+2);        mdsum += t1;
35                 t1 = *(ushort*)(addr+4);        mdsum += t2;
36                 t2 = *(ushort*)(addr+6);        mdsum += t1;
37                 t1 = *(ushort*)(addr+8);        mdsum += t2;
38                 t2 = *(ushort*)(addr+10);       mdsum += t1;
39                 t1 = *(ushort*)(addr+12);       mdsum += t2;
40                 t2 = *(ushort*)(addr+14);       mdsum += t1;
41                 mdsum += t2;
42                 len -= 16;
43                 addr += 16;
44         }
45         while(len >= 2) {
46                 mdsum += *(ushort*)addr;
47                 len -= 2;
48                 addr += 2;
49         }
50         if(x) {
51                 if(len)
52                         losum += addr[0];
53                 if(LITTLE)
54                         losum += mdsum;
55                 else
56                         hisum += mdsum;
57         } else {
58                 if(len)
59                         hisum += addr[0];
60                 if(LITTLE)
61                         hisum += mdsum;
62                 else
63                         losum += mdsum;
64         }
65
66         losum += hisum >> 8;
67         losum += (hisum & 0xff) << 8;
68         while(hisum = losum>>16)
69                 losum = hisum + (losum & 0xffff);
70
71         return losum & 0xffff;
72 }