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#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
ushort
ptclbsum(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;
}
ushort
ptclcsum(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;
}
ushort
ipcsum(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);
}
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