#include <stdio.h>
int compConstant(const unsigned char *x,const unsigned char *y)
{
  unsigned int differentbits = 0;
#define F(i) differentbits |= x[i] ^ y[i];
  F(0)
  F(1)
  F(2)
  F(3)
  F(4)
  F(5)
  F(6)
  F(7)
  return (1 & ((differentbits - 1) >> 8)) - 1; // returns 0 if equal, 0xFF..FF otherwise
}

int main(void) {
	int comp=1;
	char pw[]="secret";
	char in[7];
	int result;

	result = compConstant(pw, in);
	printf ("%d", result);

}