mirror of https://github.com/macssh/macssh.git
67 lines
1.7 KiB
C
Executable File
67 lines
1.7 KiB
C
Executable File
/* mpz_kronecker_ui -- Kronecker/Jacobi symbol. */
|
|
|
|
/*
|
|
Copyright (C) 1999, 2000 Free Software Foundation, Inc.
|
|
|
|
This file is part of the GNU MP Library.
|
|
|
|
The GNU MP Library is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as published by
|
|
the Free Software Foundation; either version 2.1 of the License, or (at your
|
|
option) any later version.
|
|
|
|
The GNU MP Library is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
|
|
License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
|
|
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
|
|
MA 02111-1307, USA.
|
|
*/
|
|
|
|
#include "gmp.h"
|
|
#include "gmp-impl.h"
|
|
#include "longlong.h"
|
|
|
|
|
|
/* This function is expected to be often used with b an odd prime, so the
|
|
code for odd b is nice and short. */
|
|
|
|
int
|
|
#if __STDC__
|
|
mpz_kronecker_ui (mpz_srcptr a, unsigned long b)
|
|
#else
|
|
mpz_kronecker_ui (a, b)
|
|
mpz_srcptr a;
|
|
unsigned long b;
|
|
#endif
|
|
{
|
|
int twos;
|
|
|
|
if (b & 1)
|
|
{
|
|
if (b != 1)
|
|
return mpn_jacobi_base (mpz_fdiv_ui (a, b), b, 0);
|
|
else
|
|
return 1; /* (a/1)=1 for any a */
|
|
}
|
|
|
|
if (b == 0)
|
|
return JACOBI_Z0 (a);
|
|
|
|
/* (a/2)=0 if a even */
|
|
if (mpz_even_p (a))
|
|
return 0;
|
|
|
|
/* (a/2)=(2/a) when a odd */
|
|
count_trailing_zeros (twos, b);
|
|
b >>= twos;
|
|
if (b == 1)
|
|
return JACOBI_TWOS_U (twos, PTR(a)[0]);
|
|
|
|
return mpn_jacobi_base (mpz_fdiv_ui (a, b), b,
|
|
JACOBI_TWOS_U_BIT1(twos, PTR(a)[0]));
|
|
}
|