Annotation of OpenXM_contrib/gmp/mpz/kronzu.c, Revision 1.1.1.2
1.1.1.2 ! ohara 1: /* mpz_kronecker_ui -- mpz+ulong Kronecker/Jacobi symbol.
1.1 maekawa 2:
1.1.1.2 ! ohara 3: Copyright 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
1.1 maekawa 4:
5: This file is part of the GNU MP Library.
6:
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 2.1 of the License, or (at your
10: option) any later version.
11:
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.
16:
17: You should have received a copy of the GNU Lesser General Public License
18: along with the GNU MP Library; see the file COPYING.LIB. If not, write to
19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
1.1.1.2 ! ohara 20: MA 02111-1307, USA. */
1.1 maekawa 21:
22: #include "gmp.h"
23: #include "gmp-impl.h"
24: #include "longlong.h"
25:
26:
1.1.1.2 ! ohara 27: /* This implementation depends on BITS_PER_MP_LIMB being even, so that
! 28: (a/2)^BITS_PER_MP_LIMB = 1 and so there's no need to pay attention to how
! 29: many low zero limbs are stripped. */
! 30: #if BITS_PER_MP_LIMB % 2 != 0
! 31: Error, error, unsupported BITS_PER_MP_LIMB
! 32: #endif
! 33:
1.1 maekawa 34:
35: int
36: mpz_kronecker_ui (mpz_srcptr a, unsigned long b)
37: {
1.1.1.2 ! ohara 38: mp_srcptr a_ptr = PTR(a);
! 39: mp_size_t a_size;
! 40: mp_limb_t a_rem;
! 41: int result_bit1;
! 42:
! 43: a_size = SIZ(a);
! 44: if (a_size == 0)
! 45: return JACOBI_0U (b);
1.1 maekawa 46:
1.1.1.2 ! ohara 47: if (b > GMP_NUMB_MAX)
1.1 maekawa 48: {
1.1.1.2 ! ohara 49: mp_limb_t blimbs[2];
! 50: mpz_t bz;
! 51: ALLOC(bz) = numberof (blimbs);
! 52: PTR(bz) = blimbs;
! 53: mpz_set_ui (bz, b);
! 54: return mpz_kronecker (a, bz);
1.1 maekawa 55: }
56:
1.1.1.2 ! ohara 57: if ((b & 1) != 0)
! 58: {
! 59: result_bit1 = JACOBI_ASGN_SU_BIT1 (a_size, b);
! 60: }
! 61: else
! 62: {
! 63: mp_limb_t a_low = a_ptr[0];
! 64: int twos;
! 65:
! 66: if (b == 0)
! 67: return JACOBI_LS0 (a_low, a_size); /* (a/0) */
! 68:
! 69: if (! (a_low & 1))
! 70: return 0; /* (even/even)=0 */
! 71:
! 72: /* (a/2)=(2/a) for a odd */
! 73: count_trailing_zeros (twos, b);
! 74: b >>= twos;
! 75: result_bit1 = (JACOBI_TWOS_U_BIT1 (twos, a_low)
! 76: ^ JACOBI_ASGN_SU_BIT1 (a_size, b));
! 77: }
1.1 maekawa 78:
79: if (b == 1)
1.1.1.2 ! ohara 80: return JACOBI_BIT1_TO_PN (result_bit1); /* (a/1)=1 for any a */
! 81:
! 82: a_size = ABS(a_size);
1.1 maekawa 83:
1.1.1.2 ! ohara 84: /* (a/b) = (a mod b / b) */
! 85: JACOBI_MOD_OR_MODEXACT_1_ODD (result_bit1, a_rem, a_ptr, a_size, b);
! 86: return mpn_jacobi_base (a_rem, (mp_limb_t) b, result_bit1);
1.1 maekawa 87: }
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