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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
140 lines
3.3 KiB
C
140 lines
3.3 KiB
C
/* mpf_eq -- Compare two floats up to a specified bit #.
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Copyright 1993, 1995, 1996, 2001, 2002, 2008, 2009 Free Software Foundation,
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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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int
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mpf_eq (mpf_srcptr u, mpf_srcptr v, mp_bitcnt_t n_bits)
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{
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mp_srcptr up, vp, p;
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mp_size_t usize, vsize, minsize, maxsize, n_limbs, i, size;
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mp_exp_t uexp, vexp;
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mp_limb_t diff;
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int cnt;
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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;
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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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up += usize; /* point just above most significant limb */
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vp += vsize; /* point just above most significant limb */
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count_leading_zeros (cnt, up[-1]);
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if ((vp[-1] >> (GMP_LIMB_BITS - 1 - cnt)) != 1)
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return 0; /* msb positions different */
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n_bits += cnt - GMP_NAIL_BITS;
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n_limbs = (n_bits + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS;
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usize = MIN (usize, n_limbs);
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vsize = MIN (vsize, n_limbs);
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#if 0
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/* Ignore zeros at the low end of U and V. */
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while (up[0] == 0)
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up++, usize--;
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while (vp[0] == 0)
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vp++, vsize--;
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#endif
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minsize = MIN (usize, vsize);
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maxsize = usize + vsize - minsize;
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up -= minsize; /* point at most significant common limb */
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vp -= minsize; /* point at most significant common limb */
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/* Compare the most significant part which has explicit limbs for U and V. */
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for (i = minsize - 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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n_bits -= (maxsize - 1) * GMP_NUMB_BITS;
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size = maxsize - minsize;
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if (size != 0)
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{
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if (up[0] != vp[0])
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return 0;
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/* Now either U or V has its limbs consumed, i.e, continues with an
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infinite number of implicit zero limbs. Check that the other operand
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has just zeros in the corresponding, relevant part. */
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if (usize > vsize)
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p = up - size;
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else
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p = vp - size;
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for (i = size - 1; i > 0; i--)
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{
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if (p[i] != 0)
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return 0;
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}
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diff = p[0];
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}
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else
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{
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/* Both U or V has its limbs consumed. */
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diff = up[0] ^ vp[0];
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}
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if (n_bits < GMP_NUMB_BITS)
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diff >>= GMP_NUMB_BITS - n_bits;
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return diff == 0;
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}
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