/*
Copyright (C) JAEHYUK CHO
All rights reserved.
Code by JaeHyuk Cho <mailto:minzkn@minzkn.com>
*/
#include <stdio.h>
#if 0
typedef unsigned int t_gcm_value;
#else
typedef int t_gcm_value;
#endif
static t_gcm_value _gcm_to_abs(t_gcm_value s_value)
{
static t_gcm_value sg_msb = (((t_gcm_value)1) << ((sizeof(t_gcm_value) << 3) - 1));
t_gcm_value s_temp;
s_temp = sg_msb >> ((sizeof(t_gcm_value) << 3) - 1);
if(s_temp != ((t_gcm_value)1))
{ /* t_gcm_value is signed type */
if((s_value & sg_msb) == sg_msb)
{ /* s_value < 0 */
s_value = -s_value;
}
}
return(s_value);
}
static t_gcm_value _gcm(t_gcm_value s_value1, t_gcm_value s_value2)
{
t_gcm_value s_temp;
if(s_value1 < s_value2)
{ /* swap */
s_temp = s_value1;
s_value1 = s_value2;
s_value2 = s_temp;
}
do
{
s_temp = s_value1 % s_value2;
if(s_temp == ((t_gcm_value)0))break;
s_value1 = s_value2;
s_value2 = s_temp;
}while(1);
return(_gcm_to_abs(s_value2));
}
void gcm(t_gcm_value s_value1, t_gcm_value s_value2)
{
t_gcm_value s_value;
s_value = _gcm(s_value1, s_value2);
(void)fprintf(stdout, "gcm(%ld, %ld) = %ld\n",
(long)s_value1, (long)s_value2, (long)s_value);
}
int main(void)
{
/* test suite */
gcm(8, 12);
gcm(12, 8);
gcm(12, 18);
gcm(3, 2);
gcm(100, 200);
gcm(300, 124);
(void)fprintf(stdout, "\n");
gcm(-8, -12);
gcm(-12, -8);
gcm(-12, -18);
gcm(-3, -2);
gcm(-100, -200);
gcm(-300, -124);
(void)fprintf(stdout, "\n");
gcm(-8, 12);
gcm(-12, 8);
gcm(-12, 18);
gcm(-3, 2);
gcm(-100, 200);
gcm(-300, 124);
(void)fprintf(stdout, "\n");
gcm(8, -12);
gcm(12, -8);
gcm(12, -18);
gcm(3, -2);
gcm(100, -200);
gcm(300, -124);
(void)fprintf(stdout, "\n");
gcm(0xffffffff, 0xffffffff);
return(0);
}
/* End of source */