1 /* mpz_kronecker_si -- mpz+long Kronecker/Jacobi symbol.
3 Copyright 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
5 This file is part of the GNU MP Library.
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or (at your
10 option) any later version.
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
25 /* After the absolute value of b is established it's treated as an unsigned
26 long, because 0x80..00 doesn't fit in a signed long. */
29 mpz_kronecker_si (mpz_srcptr a, long b)
33 mp_limb_t a_rem, b_limb;
40 #if GMP_NUMB_BITS < BITS_PER_ULONG
41 if (b > GMP_NUMB_MAX || b < -GMP_NUMB_MAX)
45 ALLOC(bz) = numberof (blimbs);
48 return mpz_kronecker (a, bz);
52 result_bit1 = JACOBI_BSGN_SS_BIT1 (a_size, b);
53 b_limb = (unsigned long) ABS (b);
56 if ((b_limb & 1) == 0)
58 mp_limb_t a_low = a_ptr[0];
62 return JACOBI_LS0 (a_low, a_size); /* (a/0) */
65 return 0; /* (even/even)=0 */
67 /* (a/2)=(2/a) for a odd */
68 count_trailing_zeros (twos, b_limb);
70 result_bit1 ^= JACOBI_TWOS_U_BIT1 (twos, a_low);
74 return JACOBI_BIT1_TO_PN (result_bit1); /* (a/1)=1 for any a */
76 result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a_size, b_limb);
79 /* (a/b) = (a mod b / b) */
80 JACOBI_MOD_OR_MODEXACT_1_ODD (result_bit1, a_rem, a_ptr, a_size, b_limb);
81 return mpn_jacobi_base (a_rem, b_limb, result_bit1);