1 /* IEEE754 floating point arithmetic
2 * single precision
3 */
4 /*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
7 * http://www.algor.co.uk
8 *
9 * ########################################################################
10 *
11 * This program is free software; you can distribute it and/or modify it
12 * under the terms of the GNU General Public License (Version 2) as
13 * published by the Free Software Foundation.
14 *
15 * This program is distributed in the hope it will be useful, but WITHOUT
16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
17 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 * for more details.
19 *
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
23 *
24 * ########################################################################
25 */
26
27
28 #include "ieee754sp.h"
29
30 /* modf function is always exact for a finite number
31 */
ieee754sp_modf(ieee754sp x,ieee754sp * ip)32 ieee754sp ieee754sp_modf(ieee754sp x, ieee754sp * ip)
33 {
34 COMPXSP;
35
36 CLEARCX;
37
38 EXPLODEXSP;
39
40 switch (xc) {
41 case IEEE754_CLASS_SNAN:
42 case IEEE754_CLASS_QNAN:
43 case IEEE754_CLASS_INF:
44 case IEEE754_CLASS_ZERO:
45 *ip = x;
46 return x;
47 case IEEE754_CLASS_DNORM:
48 /* far to small */
49 *ip = ieee754sp_zero(xs);
50 return x;
51 case IEEE754_CLASS_NORM:
52 break;
53 }
54 if (xe < 0) {
55 *ip = ieee754sp_zero(xs);
56 return x;
57 }
58 if (xe >= SP_MBITS) {
59 *ip = x;
60 return ieee754sp_zero(xs);
61 }
62 /* generate ipart mantissa by clearing bottom bits
63 */
64 *ip = buildsp(xs, xe + SP_EBIAS,
65 ((xm >> (SP_MBITS - xe)) << (SP_MBITS - xe)) &
66 ~SP_HIDDEN_BIT);
67
68 /* generate fpart mantissa by clearing top bits
69 * and normalizing (must be able to normalize)
70 */
71 xm = (xm << (32 - (SP_MBITS - xe))) >> (32 - (SP_MBITS - xe));
72 if (xm == 0)
73 return ieee754sp_zero(xs);
74
75 while ((xm >> SP_MBITS) == 0) {
76 xm <<= 1;
77 xe--;
78 }
79 return buildsp(xs, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT);
80 }
81