GNU Linux-libre 4.19.286-gnu1
[releases.git] / arch / mips / math-emu / dp_tint.c
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
24 int 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                 ieee754_setcx(IEEE754_INVALID_OPERATION);
42                 return ieee754si_indef();
43
44         case IEEE754_CLASS_INF:
45                 ieee754_setcx(IEEE754_INVALID_OPERATION);
46                 return ieee754si_overflow(xs);
47
48         case IEEE754_CLASS_ZERO:
49                 return 0;
50
51         case IEEE754_CLASS_DNORM:
52         case IEEE754_CLASS_NORM:
53                 break;
54         }
55         if (xe > 31) {
56                 /* Set invalid. We will only use overflow for floating
57                    point overflow */
58                 ieee754_setcx(IEEE754_INVALID_OPERATION);
59                 return ieee754si_overflow(xs);
60         }
61         /* oh gawd */
62         if (xe > DP_FBITS) {
63                 xm <<= xe - DP_FBITS;
64         } else if (xe < DP_FBITS) {
65                 if (xe < -1) {
66                         residue = xm;
67                         round = 0;
68                         sticky = residue != 0;
69                         xm = 0;
70                 } else {
71                         residue = xm << (64 - DP_FBITS + xe);
72                         round = (residue >> 63) != 0;
73                         sticky = (residue << 1) != 0;
74                         xm >>= DP_FBITS - xe;
75                 }
76                 /* Note: At this point upper 32 bits of xm are guaranteed
77                    to be zero */
78                 odd = (xm & 0x1) != 0x0;
79                 switch (ieee754_csr.rm) {
80                 case FPU_CSR_RN:
81                         if (round && (sticky || odd))
82                                 xm++;
83                         break;
84                 case FPU_CSR_RZ:
85                         break;
86                 case FPU_CSR_RU:        /* toward +Infinity */
87                         if ((round || sticky) && !xs)
88                                 xm++;
89                         break;
90                 case FPU_CSR_RD:        /* toward -Infinity */
91                         if ((round || sticky) && xs)
92                                 xm++;
93                         break;
94                 }
95                 /* look for valid corner case 0x80000000 */
96                 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
97                         /* This can happen after rounding */
98                         ieee754_setcx(IEEE754_INVALID_OPERATION);
99                         return ieee754si_overflow(xs);
100                 }
101                 if (round || sticky)
102                         ieee754_setcx(IEEE754_INEXACT);
103         }
104         if (xs)
105                 return -xm;
106         else
107                 return xm;
108 }