xref: /titanic_51/usr/src/lib/libm/common/m9x/frexpl.c (revision 177d5b5f8c0e969013441207a0a705ae66b08cf7)
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 2011 Nexenta Systems, Inc.  All rights reserved.
24  */
25 /*
26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27  * Use is subject to license terms.
28  */
29 
30 #if defined(ELFOBJ)
31 #pragma weak frexpl = __frexpl
32 #endif
33 
34 #include "libm.h"
35 
36 #if defined(__sparc)
37 
38 long double
39 __frexpl(long double x, int *exp) {
40 	union {
41 		unsigned i[4];
42 		long double q;
43 	} xx;
44 	unsigned hx;
45 	int e, s;
46 
47 	xx.q = x;
48 	hx = xx.i[0] & ~0x80000000;
49 
50 	if (hx >= 0x7fff0000) {	/* x is infinite or NaN */
51 		*exp = 0;
52 		return (x);
53 	}
54 
55 	e = 0;
56 	if (hx < 0x00010000) {	/* x is subnormal or zero */
57 		if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0) {
58 			*exp = 0;
59 			return (x);
60 		}
61 
62 		/* normalize x */
63 		s = xx.i[0] & 0x80000000;
64 		while ((hx | (xx.i[1] & 0xffff0000)) == 0) {
65 			hx = xx.i[1];
66 			xx.i[1] = xx.i[2];
67 			xx.i[2] = xx.i[3];
68 			xx.i[3] = 0;
69 			e -= 32;
70 		}
71 		while (hx < 0x10000) {
72 			hx = (hx << 1) | (xx.i[1] >> 31);
73 			xx.i[1] = (xx.i[1] << 1) | (xx.i[2] >> 31);
74 			xx.i[2] = (xx.i[2] << 1) | (xx.i[3] >> 31);
75 			xx.i[3] <<= 1;
76 			e--;
77 		}
78 		xx.i[0] = s | hx;
79 	}
80 
81 	/* now xx.q is normal */
82 	xx.i[0] = (xx.i[0] & ~0x7fff0000) | 0x3ffe0000;
83 	*exp = e + (hx >> 16) - 0x3ffe;
84 	return (xx.q);
85 }
86 
87 #elif defined(__x86)
88 
89 long double
90 __frexpl(long double x, int *exp) {
91 	union {
92 		unsigned i[3];
93 		long double e;
94 	} xx;
95 	unsigned hx;
96 	int e;
97 
98 	xx.e = x;
99 	hx = xx.i[2] & 0x7fff;
100 
101 	if (hx >= 0x7fff) {	/* x is infinite or NaN */
102 		*exp = 0;
103 		return (x);
104 	}
105 
106 	e = 0;
107 	if (hx < 0x0001) {	/* x is subnormal or zero */
108 		if ((xx.i[0] | xx.i[1]) == 0) {
109 			*exp = 0;
110 			return (x);
111 		}
112 
113 		/* normalize x */
114 		xx.e *= 18446744073709551616.0L;	/* 2^64 */
115 		hx = xx.i[2] & 0x7fff;
116 		e = -64;
117 	}
118 
119 	/* now xx.e is normal */
120 	xx.i[2] = (xx.i[2] & 0x8000) | 0x3ffe;
121 	*exp = e + hx - 0x3ffe;
122 	return (xx.e);
123 }
124 
125 #else
126 #error Unknown architecture
127 #endif
128