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1da177e4 LT |
1 | /* IEEE754 floating point arithmetic |
2 | * double precision: common utilities | |
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 "ieee754dp.h" | |
28 | ||
2209bcb1 | 29 | s64 ieee754dp_tlong(union ieee754dp x) |
1da177e4 LT |
30 | { |
31 | COMPXDP; | |
32 | ||
9e8bad1f | 33 | ieee754_clearcx(); |
1da177e4 LT |
34 | |
35 | EXPLODEXDP; | |
36 | FLUSHXDP; | |
37 | ||
38 | switch (xc) { | |
39 | case IEEE754_CLASS_SNAN: | |
40 | case IEEE754_CLASS_QNAN: | |
41 | case IEEE754_CLASS_INF: | |
9e8bad1f | 42 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
1da177e4 LT |
43 | return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x); |
44 | case IEEE754_CLASS_ZERO: | |
45 | return 0; | |
46 | case IEEE754_CLASS_DNORM: | |
47 | case IEEE754_CLASS_NORM: | |
48 | break; | |
49 | } | |
50 | if (xe >= 63) { | |
51 | /* look for valid corner case */ | |
52 | if (xe == 63 && xs && xm == DP_HIDDEN_BIT) | |
53 | return -0x8000000000000000LL; | |
54 | /* Set invalid. We will only use overflow for floating | |
55 | point overflow */ | |
9e8bad1f | 56 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
1da177e4 LT |
57 | return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x); |
58 | } | |
59 | /* oh gawd */ | |
60 | if (xe > DP_MBITS) { | |
61 | xm <<= xe - DP_MBITS; | |
62 | } else if (xe < DP_MBITS) { | |
63 | u64 residue; | |
64 | int round; | |
65 | int sticky; | |
66 | int odd; | |
67 | ||
68 | if (xe < -1) { | |
69 | residue = xm; | |
70 | round = 0; | |
71 | sticky = residue != 0; | |
72 | xm = 0; | |
c273625b | 73 | } else { |
1da177e4 LT |
74 | /* Shifting a u64 64 times does not work, |
75 | * so we do it in two steps. Be aware that xe | |
76 | * may be -1 */ | |
77 | residue = xm << (xe + 1); | |
78 | residue <<= 63 - DP_MBITS; | |
79 | round = (residue >> 63) != 0; | |
80 | sticky = (residue << 1) != 0; | |
81 | xm >>= DP_MBITS - xe; | |
82 | } | |
83 | odd = (xm & 0x1) != 0x0; | |
84 | switch (ieee754_csr.rm) { | |
85 | case IEEE754_RN: | |
86 | if (round && (sticky || odd)) | |
87 | xm++; | |
88 | break; | |
89 | case IEEE754_RZ: | |
90 | break; | |
91 | case IEEE754_RU: /* toward +Infinity */ | |
92 | if ((round || sticky) && !xs) | |
93 | xm++; | |
94 | break; | |
95 | case IEEE754_RD: /* toward -Infinity */ | |
96 | if ((round || sticky) && xs) | |
97 | xm++; | |
98 | break; | |
99 | } | |
100 | if ((xm >> 63) != 0) { | |
101 | /* This can happen after rounding */ | |
9e8bad1f | 102 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
1da177e4 LT |
103 | return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x); |
104 | } | |
105 | if (round || sticky) | |
9e8bad1f | 106 | ieee754_setcx(IEEE754_INEXACT); |
1da177e4 LT |
107 | } |
108 | if (xs) | |
109 | return -xm; | |
110 | else | |
111 | return xm; | |
112 | } | |
113 | ||
114 | ||
2209bcb1 | 115 | u64 ieee754dp_tulong(union ieee754dp x) |
1da177e4 | 116 | { |
2209bcb1 | 117 | union ieee754dp hb = ieee754dp_1e63(); |
1da177e4 LT |
118 | |
119 | /* what if x < 0 ?? */ | |
120 | if (ieee754dp_lt(x, hb)) | |
121 | return (u64) ieee754dp_tlong(x); | |
122 | ||
123 | return (u64) ieee754dp_tlong(ieee754dp_sub(x, hb)) | | |
124 | (1ULL << 63); | |
125 | } |