xref: /illumos-gate/usr/src/lib/libc/port/fp/_base_sup.c (revision d3b5f563)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*
28  * Copyright 2019 Joyent, Inc.
29  */
30 
31 #include "lint.h"
32 #include <sys/types.h>
33 #include "base_conversion.h"
34 #include <sys/isa_defs.h>
35 
36 /*
37  * Miscellaneous support routines used in base conversion
38  */
39 
40 static const union {
41 	unsigned int	u[2];
42 	double		d;
43 } C[] = {
44 #ifdef _LITTLE_ENDIAN
45 	{ 0x00000000u, 0x00100000u },
46 	{ 0x00000001u, 0x7ff00000u }
47 #else
48 	{ 0x00100000u, 0x00000000u },
49 	{ 0x7ff00000u, 0x00000001u }
50 #endif
51 };
52 
53 #define	minnormal	C[0].d
54 #define	signalingnan	C[1].d
55 
56 /* raise the floating point exceptions indicated by ef */
57 void
__base_conversion_set_exception(fp_exception_field_type ef)58 __base_conversion_set_exception(fp_exception_field_type ef)
59 {
60 	double	t;
61 	volatile double tstored __unused;
62 
63 	if (ef == (1 << fp_inexact)) {
64 		t = 9.999999962747097015E-1;
65 		/*
66 		 * 28 sig bits so product isn't inexact in extended
67 		 * accumulator, causing two inexact traps.
68 		 */
69 	} else if ((ef & (1 << fp_invalid)) != 0) {
70 		t = signalingnan;
71 	} else if ((ef & (1 << fp_overflow)) != 0) {
72 		t = 4.149515553422842866E+180;
73 		/*
74 		 * 28 sig bits so product isn't inexact in extended
75 		 * accumulator, causing inexact trap prior to overflow trap
76 		 * on store.
77 		 */
78 	} else if ((ef & (1 << fp_underflow)) != 0) {
79 		t = minnormal;
80 	} else
81 		return;
82 
83 	/* Storage forces exception */
84 	tstored = t * t;
85 #if defined(__lint)
86 	tstored = tstored;
87 #endif
88 }
89 
90 /*
91  * The following routine is no longer used in libc, but we have
92  * to leave it for now because it's still used by Sun's old Fortran
93  * runtime libraries.  Today this is a bug; in the days of SunOS 4.x,
94  * when the relevant design decisions were made, it was a feature.
95  *
96  * Regardless, on 32-bit, 'quadruple' under GCC is not 128 bits, so it
97  * uses uninitialized memory...
98  */
99 #pragma GCC diagnostic ignored "-Wuninitialized"
100 enum fp_class_type
__class_quadruple(quadruple * x)101 __class_quadruple(quadruple *x)
102 {
103 	quadruple_equivalence kluge;
104 
105 	kluge.x = *x;
106 	if (kluge.f.msw.exponent == 0) {	/* 0 or sub */
107 		if ((kluge.f.msw.significand == 0) &&
108 		    (kluge.f.significand2 == 0) &&
109 		    (kluge.f.significand3 == 0) &&
110 		    (kluge.f.significand4 == 0))
111 			return (fp_zero);
112 		else
113 			return (fp_subnormal);
114 	} else if (kluge.f.msw.exponent == 0x7fff) {	/* inf or nan */
115 		if ((kluge.f.msw.significand == 0) &&
116 		    (kluge.f.significand2 == 0) &&
117 		    (kluge.f.significand3 == 0) &&
118 		    (kluge.f.significand4 == 0))
119 			return (fp_infinity);
120 		else if ((kluge.f.msw.significand & 0xffff) >=
121 		    (unsigned int)0x8000)
122 			return (fp_quiet);
123 		else
124 			return (fp_signaling);
125 	} else
126 		return (fp_normal);
127 }
128