EMILE/libemile/emile_checksum.c
2005-02-02 14:25:30 +00:00

42 lines
657 B
C

static __attribute__((used)) char* rcsid = "$CVSHeader$";
/*
*
* (c) 2004 Laurent Vivier <LaurentVivier@wanadoo.fr>
*
*/
#include "libemile.h"
#ifdef USE_16BIT_CHECKSUM
int emile_checksum(unsigned char *addr, unsigned short length)
{
int j;
unsigned short sum = 0;
for (j = 0; j < length; j++)
{
sum += addr[j];
sum = (sum << 1) | (sum >> 15);
}
if (sum == 0)
sum = 0xFFFF;
return sum;
}
#else
unsigned short emile_checksum(unsigned char *addr, unsigned int length)
{
unsigned int sum = 0;
unsigned int i;
for (i = 0; i < length; i++)
{
sum += addr[i];
sum <<= 1;
sum |= (sum & 0x00010000) ? 1 : 0;
}
return sum;
}
#endif