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/*
(C) 2009-2011 Mika Ilmaranta <ilmis@nullnet.fi>
License: GPLv2
*/
#include "cksum.h"
int in_cksum(u_short *p, int n)
{
register u_short answer;
register long sum = 0;
u_short odd_byte = 0;
while(n > 1) {
sum += *p++;
n -= 2;
}
/* mop up an odd byte, if necessary */
if(n == 1){
*(u_char*)(&odd_byte) = *(u_char*)p;
sum += odd_byte;
}
sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
sum += (sum >> 16); /* add carry */
answer = ~sum; /* ones-complement, truncate */
return(answer);
}
/* EOF */
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