112 lines
2.6 KiB
C
112 lines
2.6 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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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 2.1 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; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "gmp.h"
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#include "gmp-impl.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;
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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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/* Ignore zeroes at the low end of U and V. */
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while (up[0] == 0)
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{
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up++;
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usize--;
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}
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while (vp[0] == 0)
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{
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vp++;
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vsize--;
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}
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if (usize > vsize)
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{
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if (vsize * GMP_NUMB_BITS < n_bits)
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return 0; /* surely too different */
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size = vsize;
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}
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else if (vsize > usize)
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{
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if (usize * GMP_NUMB_BITS < n_bits)
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return 0; /* surely too different */
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size = usize;
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}
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else
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{
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size = usize;
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}
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if (size > (n_bits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS)
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size = (n_bits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS;
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up += usize - size;
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vp += vsize - size;
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for (i = size - 1; i >= 0; i--)
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{
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if (up[i] != vp[i])
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return 0;
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}
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return 1;
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}
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