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/* mpf_add -- Add two floats.
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Copyright 1993, 1994, 1996, 2000, 2001 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., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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mpf_add (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
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mp_size_t usize, vsize, rsize;
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/* Handle special cases that don't work in generic code below. */
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/* If signs of U and V are different, perform subtraction. */
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if ((usize ^ vsize) < 0)
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__mpf_struct v_negated;
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v_negated._mp_size = -vsize;
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v_negated._mp_exp = v->_mp_exp;
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v_negated._mp_d = v->_mp_d;
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mpf_sub (r, u, &v_negated);
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/* Signs are now known to be the same. */
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/* Make U be the operand with the largest exponent. */
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if (u->_mp_exp < v->_mp_exp)
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ediff = u->_mp_exp - v->_mp_exp;
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/* If U extends beyond PREC, ignore the part that does. */
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/* If V extends beyond PREC, ignore the part that does.
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Note that this may make vsize negative. */
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if (vsize + ediff > prec)
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vp += vsize + ediff - prec;
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vsize = prec - ediff;
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/* Locate the least significant non-zero limb in (the needed parts
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of) U and V, to simplify the code below. */
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/* Allocate temp space for the result. Allocate
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just vsize + ediff later??? */
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tp = (mp_ptr) TMP_ALLOC (prec * BYTES_PER_MP_LIMB);
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/* V completely cancelled. */
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MPN_COPY_INCR (rp, up, usize);
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/* uuuu | uuuu | uuuu | uuuu | uuuu */
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/* vvvvvvv | vv | vvvvv | v | vv */
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/* U and V partially overlaps. */
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if (vsize + ediff <= usize)
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size = usize - ediff - vsize;
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MPN_COPY (tp, up, size);
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cy = mpn_add (tp + size, up + size, usize - size, vp, vsize);
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size = vsize + ediff - usize;
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MPN_COPY (tp, vp, size);
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cy = mpn_add (tp + size, up, usize, vp + size, usize - ediff);
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rsize = vsize + ediff;
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size = vsize + ediff - usize;
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MPN_COPY (tp, vp, vsize);
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MPN_ZERO (tp + vsize, ediff - usize);
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MPN_COPY (tp + size, up, usize);
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rsize = size + usize;
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MPN_COPY (rp, tp, rsize);
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r->_mp_size = negate ? -rsize : rsize;