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/* mpf_add -- Add two floats.
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Copyright 1993, 1994, 1996, 2000, 2001, 2005 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 either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any
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later version.
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or both in parallel, as here.
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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 General Public License
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for more details.
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You should have received copies of the GNU General Public License and the
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GNU Lesser General Public License along with the GNU MP Library. If not,
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see https://www.gnu.org/licenses/. */
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#include "gmp.h"
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#include "gmp-impl.h"
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void
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mpf_add (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
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{
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mp_srcptr up, vp;
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mp_ptr rp, tp;
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mp_size_t usize, vsize, rsize;
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mp_size_t prec;
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mp_exp_t uexp;
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mp_size_t ediff;
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mp_limb_t cy;
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int negate;
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TMP_DECL;
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usize = u->_mp_size;
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vsize = v->_mp_size;
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/* Handle special cases that don't work in generic code below. */
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if (usize == 0)
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{
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set_r_v_maybe:
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if (r != v)
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mpf_set (r, v);
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return;
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}
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if (vsize == 0)
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{
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v = u;
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goto set_r_v_maybe;
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}
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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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{
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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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return;
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}
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TMP_MARK;
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/* Signs are now known to be the same. */
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negate = usize < 0;
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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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{
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mpf_srcptr t;
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t = u; u = v; v = t;
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usize = u->_mp_size;
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vsize = v->_mp_size;
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}
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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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rp = r->_mp_d;
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prec = r->_mp_prec;
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uexp = u->_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 (usize > prec)
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{
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up += usize - prec;
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usize = prec;
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}
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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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{
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vp += vsize + ediff - prec;
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vsize = prec - ediff;
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}
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#if 0
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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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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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/* Allocate temp space for the result. Allocate
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just vsize + ediff later??? */
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tp = TMP_ALLOC_LIMBS (prec);
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if (ediff >= prec)
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{
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/* V completely cancelled. */
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if (rp != up)
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MPN_COPY_INCR (rp, up, usize);
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rsize = usize;
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}
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else
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{
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/* uuuu | uuuu | uuuu | uuuu | uuuu */
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/* vvvvvvv | vv | vvvvv | v | vv */
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if (usize > ediff)
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{
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/* U and V partially overlaps. */
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if (vsize + ediff <= usize)
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{
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/* uuuu */
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/* v */
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mp_size_t size;
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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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rsize = usize;
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}
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else
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{
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/* uuuu */
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/* vvvvv */
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mp_size_t size;
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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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}
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}
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else
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{
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/* uuuu */
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/* vv */
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mp_size_t size;
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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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cy = 0;
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rsize = size + usize;
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}
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MPN_COPY (rp, tp, rsize);
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rp[rsize] = cy;
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rsize += cy;
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uexp += cy;
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}
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r->_mp_size = negate ? -rsize : rsize;
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r->_mp_exp = uexp;
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TMP_FREE;
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}
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