1 // SPDX-License-Identifier: GPL-2.0-only
2 /* IEEE754 floating point arithmetic
3 * single precision
4 */
5 /*
6 * MIPS floating point support
7 * Copyright (C) 1994-2000 Algorithmics Ltd.
8 */
9
10 #include "ieee754sp.h"
11
12 int ieee754sp_tint(union ieee754sp x)
13 {
14 u32 residue;
15 int round;
16 int sticky;
17 int odd;
18
19 COMPXSP;
20
21 ieee754_clearcx();
22
23 EXPLODEXSP;
24 FLUSHXSP;
25
26 switch (xc) {
27 case IEEE754_CLASS_SNAN:
28 case IEEE754_CLASS_QNAN:
29 ieee754_setcx(IEEE754_INVALID_OPERATION);
30 return ieee754si_indef();
31
32 case IEEE754_CLASS_INF:
33 ieee754_setcx(IEEE754_INVALID_OPERATION);
34 return ieee754si_overflow(xs);
35
36 case IEEE754_CLASS_ZERO:
37 return 0;
38
39 case IEEE754_CLASS_DNORM:
40 case IEEE754_CLASS_NORM:
41 break;
42 }
43 if (xe >= 31) {
44 /* look for valid corner case */
45 if (xe == 31 && xs && xm == SP_HIDDEN_BIT)
46 return -0x80000000;
47 /* Set invalid. We will only use overflow for floating
48 point overflow */
49 ieee754_setcx(IEEE754_INVALID_OPERATION);
50 return ieee754si_overflow(xs);
51 }
52 /* oh gawd */
53 if (xe > SP_FBITS) {
54 xm <<= xe - SP_FBITS;
55 } else {
56 if (xe < -1) {
57 residue = xm;
58 round = 0;
59 sticky = residue != 0;
60 xm = 0;
61 } else {
62 /* Shifting a u32 32 times does not work,
63 * so we do it in two steps. Be aware that xe
64 * may be -1 */
65 residue = xm << (xe + 1);
66 residue <<= 31 - SP_FBITS;
67 round = (residue >> 31) != 0;
68 sticky = (residue << 1) != 0;
69 xm >>= SP_FBITS - xe;
70 }
71 odd = (xm & 0x1) != 0x0;
72 switch (ieee754_csr.rm) {
73 case FPU_CSR_RN:
74 if (round && (sticky || odd))
75 xm++;
76 break;
77 case FPU_CSR_RZ:
78 break;
79 case FPU_CSR_RU: /* toward +Infinity */
80 if ((round || sticky) && !xs)
81 xm++;
82 break;
83 case FPU_CSR_RD: /* toward -Infinity */
84 if ((round || sticky) && xs)
85 xm++;
86 break;
87 }
88 if ((xm >> 31) != 0) {
89 /* This can happen after rounding */
90 ieee754_setcx(IEEE754_INVALID_OPERATION);
91 return ieee754si_overflow(xs);
92 }
93 if (round || sticky)
94 ieee754_setcx(IEEE754_INEXACT);
95 }
96 if (xs)
97 return -xm;
98 else
99 return xm;
100 }
101
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.