mirror of
https://github.com/9fans/plan9port.git
synced 2025-01-15 11:20:03 +00:00
69 lines
1.1 KiB
C
69 lines
1.1 KiB
C
|
#include <u.h>
|
||
|
|
#include <libc.h>
|
||
|
|
#include <ip.h>
|
||
|
|
|
||
|
|
static short endian = 1;
|
||
|
|
static uchar* aendian = (uchar*)&endian;
|
||
|
|
#define LITTLE *aendian
|
||
|
|
|
||
|
|
ushort
|
||
|
|
ptclbsum(uchar *addr, int len)
|
||
|
|
{
|
||
|
|
ulong losum, hisum, mdsum, x;
|
||
|
|
ulong t1, t2;
|
||
|
|
|
||
|
|
losum = 0;
|
||
|
|
hisum = 0;
|
||
|
|
mdsum = 0;
|
||
|
|
|
||
|
|
x = 0;
|
||
|
|
if((ulong)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;
|
||
|
|
}
|