xref: /titanic_52/usr/src/lib/libm/common/m9x/truncl.c (revision ddc0e0b53c661f6e439e3b7072b3ef353eadb4af)
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 #pragma weak __truncl = truncl
31 
32 #include "libm.h"
33 
34 #if defined(__sparc)
35 long double
36 truncl(long double x) {
37 	union {
38 		unsigned i[4];
39 		long double q;
40 	} xx;
41 	unsigned hx, sx;
42 	int j;
43 
44 	xx.q = x;
45 	sx = xx.i[0] & 0x80000000;
46 	hx = xx.i[0] & ~0x80000000;
47 
48 	/* handle trivial cases */
49 	if (hx >= 0x406f0000) /* |x| >= 2^112 + ... or x is nan */
50 		return (hx >= 0x7fff0000 ? x + x : x);
51 
52 	/* handle |x| < 1 */
53 	if (hx < 0x3fff0000)
54 		return (sx ? -0.0L : 0.0L);
55 
56 	j = 0x406f - (hx >> 16);		/* 1 <= j <= 112 */
57 	xx.i[0] = hx;
58 	if (j >= 96) {				/* 96 <= j <= 112 */
59 		xx.i[0] &= ~((1 << (j - 96)) - 1);
60 		xx.i[1] = xx.i[2] = xx.i[3] = 0;
61 	} else if (j >= 64) {			/* 64 <= j <= 95 */
62 		xx.i[1] &= ~((1 << (j - 64)) - 1);
63 		xx.i[2] = xx.i[3] = 0;
64 	} else if (j >= 32) {			/* 32 <= j <= 63 */
65 		xx.i[2] &= ~((1 << (j - 32)) - 1);
66 		xx.i[3] = 0;
67 	} else					/* 1 <= j <= 31 */
68 		xx.i[3] &= ~((1 << j) - 1);
69 
70 	/* negate result if need be */
71 	if (sx)
72 		xx.i[0] |= 0x80000000;
73 	return (xx.q);
74 }
75 #elif defined(__x86)
76 long double
77 truncl(long double x) {
78 	union {
79 		unsigned i[3];
80 		long double e;
81 	} xx;
82 	int ex, sx, i;
83 
84 	xx.e = x;
85 	ex = xx.i[2] & 0x7fff;
86 	sx = xx.i[2] & 0x8000;
87 	if (ex < 0x403e) {	/* |x| < 2^63 */
88 		if (ex < 0x3fff)	/* |x| < 1 */
89 			return (sx ? -0.0L : 0.0L);
90 
91 		/* chop x at the integer bit */
92 		if (ex < 0x401e) {
93 			i = 1 << (0x401d - ex);
94 			xx.i[1] &= ~(i | (i - 1));
95 			xx.i[0] = 0;
96 		} else {
97 			i = 1 << (0x403d - ex);
98 			xx.i[0] &= ~(i | (i - 1));
99 		}
100 		return (xx.e);
101 	} else if (ex < 0x7fff)	/* x is integral */
102 		return (x);
103 	else			/* inf or nan */
104 		return (x + x);
105 }
106 #else
107 #error Unknown architecture
108 #endif	/* defined(__sparc) || defined(__x86) */
109