| ---
tptclbsum.c (1158B)
---
1 #include
2 #include
3 #include
4
5 static short endian = 1;
6 static uchar* aendian = (uchar*)&endian;
7 #define LITTLE *aendian
8
9 ushort
10 ptclbsum(uchar *addr, int len)
11 {
12 ulong losum, hisum, mdsum, x;
13 ulong t1, t2;
14
15 losum = 0;
16 hisum = 0;
17 mdsum = 0;
18
19 x = 0;
20 if((ulong)addr & 1) {
21 if(len) {
22 hisum += addr[0];
23 len--;
24 addr++;
25 }
26 x = 1;
27 }
28 while(len >= 16) {
29 t1 = *(ushort*)(addr+0);
30 t2 = *(ushort*)(addr+2); mdsum += t1;
31 t1 = *(ushort*)(addr+4); mdsum += t2;
32 t2 = *(ushort*)(addr+6); mdsum += t1;
33 t1 = *(ushort*)(addr+8); mdsum += t2;
34 t2 = *(ushort*)(addr+10); mdsum += t1;
35 t1 = *(ushort*)(addr+12); mdsum += t2;
36 t2 = *(ushort*)(addr+14); mdsum += t1;
37 mdsum += t2;
38 len -= 16;
39 addr += 16;
40 }
41 while(len >= 2) {
42 mdsum += *(ushort*)addr;
43 len -= 2;
44 addr += 2;
45 }
46 if(x) {
47 if(len)
48 losum += addr[0];
49 if(LITTLE)
50 losum += mdsum;
51 else
52 hisum += mdsum;
53 } else {
54 if(len)
55 hisum += addr[0];
56 if(LITTLE)
57 hisum += mdsum;
58 else
59 losum += mdsum;
60 }
61
62 losum += hisum >> 8;
63 losum += (hisum & 0xff) << 8;
64 while(hisum = losum>>16)
65 losum = hisum + (losum & 0xffff);
66
67 return losum & 0xffff;
68 } |