#include "os.h"#include <mp.h> #define iseven(a)	(((a)->p[0] & 1) == 0) // use extended gcd to find the multiplicative inverse// res = b**-1 mod mvoidmpinvert(mpint *b, mpint *m, mpint *res){	mpint *dc1, *dc2;	// don't care 	dc1 = mpnew(0);	dc2 = mpnew(0);	mpextendedgcd(b, m, dc1, res, dc2);	if(mpcmp(dc1, mpone) != 0)		abort();	mpmod(res, m, res);	mpfree(dc1);	mpfree(dc2);}