1 /* IEEE754 floating point arithmetic
2 * double precision: common utilities
3 */
4 /*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
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
ieee754dp_tlong(ieee754dp x)29 s64 ieee754dp_tlong(ieee754dp x)
30 {
31 COMPXDP;
32
33 CLEARCX;
34
35 EXPLODEXDP;
36 FLUSHXDP;
37
38 switch (xc) {
39 case IEEE754_CLASS_SNAN:
40 case IEEE754_CLASS_QNAN:
41 case IEEE754_CLASS_INF:
42 SETCX(IEEE754_INVALID_OPERATION);
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 */
56 SETCX(IEEE754_INVALID_OPERATION);
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;
73 } else {
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 */
102 SETCX(IEEE754_INVALID_OPERATION);
103 return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x);
104 }
105 if (round || sticky)
106 SETCX(IEEE754_INEXACT);
107 }
108 if (xs)
109 return -xm;
110 else
111 return xm;
112 }
113
114
ieee754dp_tulong(ieee754dp x)115 u64 ieee754dp_tulong(ieee754dp x)
116 {
117 ieee754dp hb = ieee754dp_1e63();
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 }
126