100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
/* mpf_eq -- Compare two floats up to a specified bit #.
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Copyright 1993, 1995, 1996, 2001, 2002 Free Software Foundation, Inc.
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Copyright 2009 Jason Moxham
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This file is part of the MPIR Library.
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The MPIR 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
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by the Free Software Foundation; either version 2.1 of the License, or (at
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your option) any later version.
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The MPIR 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 MPIR Library; see the file COPYING.LIB. If not, write
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to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA.
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*/
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#include "mpir.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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int
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mpf_eq (mpf_srcptr u, mpf_srcptr v, unsigned long int n_bits)
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{
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mp_srcptr up, vp;
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mp_size_t usize, vsize, size, i, cu, cv, n, k;
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mp_limb_t uval, vval;
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mp_exp_t uexp, vexp;
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uexp = u->_mp_exp;
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vexp = v->_mp_exp;
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usize = u->_mp_size;
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vsize = v->_mp_size;
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/* 1. Are the signs different? */
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if ((usize ^ vsize) >= 0)
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{
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/* U and V are both non-negative or both negative. */
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if (usize == 0)
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return vsize == 0;
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if (vsize == 0)
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return 0;
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/* Fall out. */
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}
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else
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{
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/* Either U or V is negative, but not both. */
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return 0;
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}
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/* U and V have the same sign and are both non-zero. */
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/* 2. Are the exponents different? */
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if (uexp > vexp)
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return 0; /* ??? handle (uexp = vexp + 1) */
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if (vexp > uexp)
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return 0; /* ??? handle (vexp = uexp + 1) */
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usize = ABS (usize);
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vsize = ABS (vsize);
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up = u->_mp_d;
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vp = v->_mp_d;
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count_leading_zeros (cu, up[usize - 1]);
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count_leading_zeros (cv, vp[vsize - 1]);
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if (cu != cv)
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return 0;
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n = BITS_TO_LIMBS (n_bits + cu);
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//compair bottom limb
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k = n * GMP_NUMB_BITS - n_bits - cu;
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uval = vval = 0;
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if (usize - n >= 0)
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uval = up[usize - n];
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if (vsize - n >= 0)
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vval = vp[vsize - n];
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if ((uval >> k) != (vval >> k))
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return 0;
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// compair rest of limbs
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for (i = usize - n + 1; i < usize ; i++)
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{
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uval = vval = 0;
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if (i >= 0)
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uval = up[i];
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if (i - usize + vsize >= 0)
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vval = vp[i - usize + vsize];
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if (uval != vval)
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return 0;
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}
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return 1;
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}
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