Annotation of OpenXM_contrib/gmp/mpf/add.c, Revision 1.1.1.3
1.1 maekawa 1: /* mpf_add -- Add two floats.
2:
1.1.1.3 ! ohara 3: Copyright 1993, 1994, 1996, 2000, 2001 Free Software Foundation, Inc.
1.1 maekawa 4:
5: This file is part of the GNU MP Library.
6:
7: The GNU MP Library is free software; you can redistribute it and/or modify
1.1.1.2 maekawa 8: it under the terms of the GNU Lesser General Public License as published by
9: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1 maekawa 10: option) any later version.
11:
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
1.1.1.2 maekawa 14: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
1.1 maekawa 15: License for more details.
16:
1.1.1.2 maekawa 17: You should have received a copy of the GNU Lesser General Public License
1.1 maekawa 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. */
21:
22: #include "gmp.h"
23: #include "gmp-impl.h"
24:
25: void
26: mpf_add (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
27: {
28: mp_srcptr up, vp;
29: mp_ptr rp, tp;
30: mp_size_t usize, vsize, rsize;
31: mp_size_t prec;
32: mp_exp_t uexp;
33: mp_size_t ediff;
34: mp_limb_t cy;
35: int negate;
36: TMP_DECL (marker);
37:
38: usize = u->_mp_size;
39: vsize = v->_mp_size;
40:
41: /* Handle special cases that don't work in generic code below. */
42: if (usize == 0)
43: {
1.1.1.3 ! ohara 44: set_r_v_maybe:
! 45: if (r != v)
! 46: mpf_set (r, v);
1.1 maekawa 47: return;
48: }
49: if (vsize == 0)
50: {
1.1.1.3 ! ohara 51: v = u;
! 52: goto set_r_v_maybe;
1.1 maekawa 53: }
54:
55: /* If signs of U and V are different, perform subtraction. */
56: if ((usize ^ vsize) < 0)
57: {
58: __mpf_struct v_negated;
59: v_negated._mp_size = -vsize;
60: v_negated._mp_exp = v->_mp_exp;
61: v_negated._mp_d = v->_mp_d;
62: mpf_sub (r, u, &v_negated);
63: return;
64: }
65:
66: TMP_MARK (marker);
67:
68: /* Signs are now known to be the same. */
69: negate = usize < 0;
70:
71: /* Make U be the operand with the largest exponent. */
72: if (u->_mp_exp < v->_mp_exp)
73: {
74: mpf_srcptr t;
75: t = u; u = v; v = t;
76: usize = u->_mp_size;
77: vsize = v->_mp_size;
78: }
79:
80: usize = ABS (usize);
81: vsize = ABS (vsize);
82: up = u->_mp_d;
83: vp = v->_mp_d;
84: rp = r->_mp_d;
85: prec = r->_mp_prec;
86: uexp = u->_mp_exp;
87: ediff = u->_mp_exp - v->_mp_exp;
88:
89: /* If U extends beyond PREC, ignore the part that does. */
90: if (usize > prec)
91: {
92: up += usize - prec;
93: usize = prec;
94: }
95:
96: /* If V extends beyond PREC, ignore the part that does.
97: Note that this may make vsize negative. */
98: if (vsize + ediff > prec)
99: {
100: vp += vsize + ediff - prec;
101: vsize = prec - ediff;
102: }
103:
104: #if 0
105: /* Locate the least significant non-zero limb in (the needed parts
106: of) U and V, to simplify the code below. */
107: while (up[0] == 0)
108: up++, usize--;
109: while (vp[0] == 0)
110: vp++, vsize--;
111: #endif
112:
113: /* Allocate temp space for the result. Allocate
114: just vsize + ediff later??? */
115: tp = (mp_ptr) TMP_ALLOC (prec * BYTES_PER_MP_LIMB);
116:
117: if (ediff >= prec)
118: {
119: /* V completely cancelled. */
1.1.1.3 ! ohara 120: if (rp != up)
! 121: MPN_COPY_INCR (rp, up, usize);
1.1 maekawa 122: rsize = usize;
123: }
124: else
125: {
126: /* uuuu | uuuu | uuuu | uuuu | uuuu */
127: /* vvvvvvv | vv | vvvvv | v | vv */
128:
129: if (usize > ediff)
130: {
131: /* U and V partially overlaps. */
132: if (vsize + ediff <= usize)
133: {
134: /* uuuu */
135: /* v */
136: mp_size_t size;
137: size = usize - ediff - vsize;
138: MPN_COPY (tp, up, size);
139: cy = mpn_add (tp + size, up + size, usize - size, vp, vsize);
140: rsize = usize;
141: }
142: else
143: {
144: /* uuuu */
145: /* vvvvv */
146: mp_size_t size;
147: size = vsize + ediff - usize;
148: MPN_COPY (tp, vp, size);
149: cy = mpn_add (tp + size, up, usize, vp + size, usize - ediff);
150: rsize = vsize + ediff;
151: }
152: }
153: else
154: {
155: /* uuuu */
156: /* vv */
157: mp_size_t size;
158: size = vsize + ediff - usize;
159: MPN_COPY (tp, vp, vsize);
160: MPN_ZERO (tp + vsize, ediff - usize);
161: MPN_COPY (tp + size, up, usize);
162: cy = 0;
163: rsize = size + usize;
164: }
165:
166: MPN_COPY (rp, tp, rsize);
167: rp[rsize] = cy;
168: rsize += cy;
169: uexp += cy;
170: }
171:
172: r->_mp_size = negate ? -rsize : rsize;
173: r->_mp_exp = uexp;
174: TMP_FREE (marker);
175: }
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