GNU Linux-libre 4.19.286-gnu1
[releases.git] / arch / mips / math-emu / sp_tint.c
1 /* IEEE754 floating point arithmetic
2  * single precision
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 "ieee754sp.h"
23
24 int ieee754sp_tint(union ieee754sp x)
25 {
26         u32 residue;
27         int round;
28         int sticky;
29         int odd;
30
31         COMPXSP;
32
33         ieee754_clearcx();
34
35         EXPLODEXSP;
36         FLUSHXSP;
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                 /* look for valid corner case */
57                 if (xe == 31 && xs && xm == SP_HIDDEN_BIT)
58                         return -0x80000000;
59                 /* Set invalid. We will only use overflow for floating
60                    point overflow */
61                 ieee754_setcx(IEEE754_INVALID_OPERATION);
62                 return ieee754si_overflow(xs);
63         }
64         /* oh gawd */
65         if (xe > SP_FBITS) {
66                 xm <<= xe - SP_FBITS;
67         } else {
68                 if (xe < -1) {
69                         residue = xm;
70                         round = 0;
71                         sticky = residue != 0;
72                         xm = 0;
73                 } else {
74                         /* Shifting a u32 32 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 <<= 31 - SP_FBITS;
79                         round = (residue >> 31) != 0;
80                         sticky = (residue << 1) != 0;
81                         xm >>= SP_FBITS - xe;
82                 }
83                 odd = (xm & 0x1) != 0x0;
84                 switch (ieee754_csr.rm) {
85                 case FPU_CSR_RN:
86                         if (round && (sticky || odd))
87                                 xm++;
88                         break;
89                 case FPU_CSR_RZ:
90                         break;
91                 case FPU_CSR_RU:        /* toward +Infinity */
92                         if ((round || sticky) && !xs)
93                                 xm++;
94                         break;
95                 case FPU_CSR_RD:        /* toward -Infinity */
96                         if ((round || sticky) && xs)
97                                 xm++;
98                         break;
99                 }
100                 if ((xm >> 31) != 0) {
101                         /* This can happen after rounding */
102                         ieee754_setcx(IEEE754_INVALID_OPERATION);
103                         return ieee754si_overflow(xs);
104                 }
105                 if (round || sticky)
106                         ieee754_setcx(IEEE754_INEXACT);
107         }
108         if (xs)
109                 return -xm;
110         else
111                 return xm;
112 }