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b58ddff026
* merged mpfr 3.0.0 and gmp 5.0.1 in buildtools trunk git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@37378 a95241bf-73f2-0310-859d-f6bbb57e9c96
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/* mpz_kronecker_si -- mpz+long Kronecker/Jacobi symbol.
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Copyright 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
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#include "gmp.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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/* After the absolute value of b is established it's treated as an unsigned
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long, because 0x80..00 doesn't fit in a signed long. */
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int
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mpz_kronecker_si (mpz_srcptr a, long b)
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{
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mp_srcptr a_ptr;
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mp_size_t a_size;
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mp_limb_t a_rem, b_limb;
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int result_bit1;
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a_size = SIZ(a);
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if (a_size == 0)
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return JACOBI_0S (b);
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#if GMP_NUMB_BITS < BITS_PER_ULONG
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if (b > GMP_NUMB_MAX || b < -GMP_NUMB_MAX)
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{
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mp_limb_t blimbs[2];
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mpz_t bz;
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ALLOC(bz) = numberof (blimbs);
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PTR(bz) = blimbs;
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mpz_set_si (bz, b);
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return mpz_kronecker (a, bz);
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}
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#endif
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result_bit1 = JACOBI_BSGN_SS_BIT1 (a_size, b);
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b_limb = (unsigned long) ABS (b);
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a_ptr = PTR(a);
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if ((b_limb & 1) == 0)
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{
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mp_limb_t a_low = a_ptr[0];
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int twos;
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if (b_limb == 0)
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return JACOBI_LS0 (a_low, a_size); /* (a/0) */
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if (! (a_low & 1))
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return 0; /* (even/even)=0 */
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/* (a/2)=(2/a) for a odd */
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count_trailing_zeros (twos, b_limb);
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b_limb >>= twos;
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result_bit1 ^= JACOBI_TWOS_U_BIT1 (twos, a_low);
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}
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if (b_limb == 1)
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return JACOBI_BIT1_TO_PN (result_bit1); /* (a/1)=1 for any a */
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result_bit1 ^= JACOBI_ASGN_SU_BIT1 (a_size, b_limb);
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a_size = ABS(a_size);
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/* (a/b) = (a mod b / b) */
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JACOBI_MOD_OR_MODEXACT_1_ODD (result_bit1, a_rem, a_ptr, a_size, b_limb);
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return mpn_jacobi_base (a_rem, b_limb, result_bit1);
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}
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