EMILE/libemile/emile_checksum.c

static __attribute__((used)) char* rcsid = "$CVSHeader$";
/*
 *
 * (c) 2004 Laurent Vivier <Laurent@lvivier.info>
 *
 */

#include "libemile.h"

unsigned short emile_checksum(unsigned char *addr, unsigned int 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;
}

unsigned short emile_checksum_ATA(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;
}