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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 * This program is free software; you can distribute it and/or modify it
9 * under the terms of the GNU General Public License (Version 2) as
10 * published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * for more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 */
21
22#include "ieee754dp.h"
23
24int ieee754dp_tint(union ieee754dp x)
25{
26 u64 residue;
27 int round;
28 int sticky;
29 int odd;
30
31 COMPXDP;
32
33 ieee754_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 ieee754_setcx(IEEE754_INVALID_OPERATION);
43 return ieee754si_indef();
44
45 case IEEE754_CLASS_ZERO:
46 return 0;
47
48 case IEEE754_CLASS_DNORM:
49 case IEEE754_CLASS_NORM:
50 break;
51 }
52 if (xe > 31) {
53 /* Set invalid. We will only use overflow for floating
54 point overflow */
55 ieee754_setcx(IEEE754_INVALID_OPERATION);
56 return ieee754si_indef();
57 }
58 /* oh gawd */
59 if (xe > DP_FBITS) {
60 xm <<= xe - DP_FBITS;
61 } else if (xe < DP_FBITS) {
62 if (xe < -1) {
63 residue = xm;
64 round = 0;
65 sticky = residue != 0;
66 xm = 0;
67 } else {
68 residue = xm << (64 - DP_FBITS + xe);
69 round = (residue >> 63) != 0;
70 sticky = (residue << 1) != 0;
71 xm >>= DP_FBITS - xe;
72 }
73 /* Note: At this point upper 32 bits of xm are guaranteed
74 to be zero */
75 odd = (xm & 0x1) != 0x0;
76 switch (ieee754_csr.rm) {
77 case FPU_CSR_RN:
78 if (round && (sticky || odd))
79 xm++;
80 break;
81 case FPU_CSR_RZ:
82 break;
83 case FPU_CSR_RU: /* toward +Infinity */
84 if ((round || sticky) && !xs)
85 xm++;
86 break;
87 case FPU_CSR_RD: /* toward -Infinity */
88 if ((round || sticky) && xs)
89 xm++;
90 break;
91 }
92 /* look for valid corner case 0x80000000 */
93 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
94 /* This can happen after rounding */
95 ieee754_setcx(IEEE754_INVALID_OPERATION);
96 return ieee754si_indef();
97 }
98 if (round || sticky)
99 ieee754_setcx(IEEE754_INEXACT);
100 }
101 if (xs)
102 return -xm;
103 else
104 return xm;
105}