1 /* mpf_add -- Add two floats.
3 Copyright (C) 1993, 1994, 1996 Free Software Foundation, Inc.
5 This file is part of the GNU MP Library.
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of the GNU Library General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or (at your
10 option) any later version.
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
15 License for more details.
17 You should have received a copy of the GNU Library General Public License
18 along with the GNU MP Library; see the file COPYING.LIB. If not, write to
19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20 MA 02111-1307, USA. */
27 mpf_add (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
37 mp_size_t usize, vsize, rsize;
48 /* Handle special cases that don't work in generic code below. */
60 /* If signs of U and V are different, perform subtraction. */
61 if ((usize ^ vsize) < 0)
63 __mpf_struct v_negated;
64 v_negated._mp_size = -vsize;
65 v_negated._mp_exp = v->_mp_exp;
66 v_negated._mp_d = v->_mp_d;
67 mpf_sub (r, u, &v_negated);
73 /* Signs are now known to be the same. */
76 /* Make U be the operand with the largest exponent. */
77 if (u->_mp_exp < v->_mp_exp)
92 ediff = u->_mp_exp - v->_mp_exp;
94 /* If U extends beyond PREC, ignore the part that does. */
101 /* If V extends beyond PREC, ignore the part that does.
102 Note that this may make vsize negative. */
103 if (vsize + ediff > prec)
105 vp += vsize + ediff - prec;
106 vsize = prec - ediff;
110 /* Locate the least significant non-zero limb in (the needed parts
111 of) U and V, to simplify the code below. */
118 /* Allocate temp space for the result. Allocate
119 just vsize + ediff later??? */
120 tp = (mp_ptr) TMP_ALLOC (prec * BYTES_PER_MP_LIMB);
124 /* V completely cancelled. */
126 MPN_COPY (rp, up, usize);
131 /* uuuu | uuuu | uuuu | uuuu | uuuu */
132 /* vvvvvvv | vv | vvvvv | v | vv */
136 /* U and V partially overlaps. */
137 if (vsize + ediff <= usize)
142 size = usize - ediff - vsize;
143 MPN_COPY (tp, up, size);
144 cy = mpn_add (tp + size, up + size, usize - size, vp, vsize);
152 size = vsize + ediff - usize;
153 MPN_COPY (tp, vp, size);
154 cy = mpn_add (tp + size, up, usize, vp + size, usize - ediff);
155 rsize = vsize + ediff;
163 size = vsize + ediff - usize;
164 MPN_COPY (tp, vp, vsize);
165 MPN_ZERO (tp + vsize, ediff - usize);
166 MPN_COPY (tp + size, up, usize);
168 rsize = size + usize;
171 MPN_COPY (rp, tp, rsize);
177 r->_mp_size = negate ? -rsize : rsize;