Subversion Repositories planix.SVN

#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 m
void
mpinvert(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);
}