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1da177e4 LT |
1 | /* IEEE754 floating point arithmetic |
2 | * single precision | |
3 | */ | |
4 | /* | |
5 | * MIPS floating point support | |
6 | * Copyright (C) 1994-2000 Algorithmics Ltd. | |
1da177e4 LT |
7 | * |
8 | * ######################################################################## | |
9 | * | |
10 | * This program is free software; you can distribute it and/or modify it | |
11 | * under the terms of the GNU General Public License (Version 2) as | |
12 | * published by the Free Software Foundation. | |
13 | * | |
14 | * This program is distributed in the hope it will be useful, but WITHOUT | |
15 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
16 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
17 | * for more details. | |
18 | * | |
19 | * You should have received a copy of the GNU General Public License along | |
20 | * with this program; if not, write to the Free Software Foundation, Inc., | |
21 | * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. | |
22 | * | |
23 | * ######################################################################## | |
24 | */ | |
25 | ||
26 | ||
27 | #include "ieee754sp.h" | |
28 | ||
29 | /* modf function is always exact for a finite number | |
30 | */ | |
24da36cd | 31 | ieee754sp ieee754sp_modf(ieee754sp x, ieee754sp *ip) |
1da177e4 LT |
32 | { |
33 | COMPXSP; | |
34 | ||
35 | CLEARCX; | |
36 | ||
37 | EXPLODEXSP; | |
38 | ||
39 | switch (xc) { | |
40 | case IEEE754_CLASS_SNAN: | |
41 | case IEEE754_CLASS_QNAN: | |
42 | case IEEE754_CLASS_INF: | |
43 | case IEEE754_CLASS_ZERO: | |
44 | *ip = x; | |
45 | return x; | |
46 | case IEEE754_CLASS_DNORM: | |
47 | /* far to small */ | |
48 | *ip = ieee754sp_zero(xs); | |
49 | return x; | |
50 | case IEEE754_CLASS_NORM: | |
51 | break; | |
52 | } | |
53 | if (xe < 0) { | |
54 | *ip = ieee754sp_zero(xs); | |
55 | return x; | |
56 | } | |
57 | if (xe >= SP_MBITS) { | |
58 | *ip = x; | |
59 | return ieee754sp_zero(xs); | |
60 | } | |
61 | /* generate ipart mantissa by clearing bottom bits | |
62 | */ | |
63 | *ip = buildsp(xs, xe + SP_EBIAS, | |
64 | ((xm >> (SP_MBITS - xe)) << (SP_MBITS - xe)) & | |
65 | ~SP_HIDDEN_BIT); | |
66 | ||
67 | /* generate fpart mantissa by clearing top bits | |
68 | * and normalizing (must be able to normalize) | |
69 | */ | |
70 | xm = (xm << (32 - (SP_MBITS - xe))) >> (32 - (SP_MBITS - xe)); | |
71 | if (xm == 0) | |
72 | return ieee754sp_zero(xs); | |
73 | ||
74 | while ((xm >> SP_MBITS) == 0) { | |
75 | xm <<= 1; | |
76 | xe--; | |
77 | } | |
78 | return buildsp(xs, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT); | |
79 | } |