xref: /titanic_50/usr/src/lib/libm/common/m9x/truncl.c (revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8)
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 truncl = __truncl
32 #endif
33 
34 #include "libm.h"
35 
36 #if defined(__sparc)
37 long double
38 truncl(long double x) {
39 	union {
40 		unsigned i[4];
41 		long double q;
42 	} xx;
43 	unsigned hx, sx;
44 	int j;
45 
46 	xx.q = x;
47 	sx = xx.i[0] & 0x80000000;
48 	hx = xx.i[0] & ~0x80000000;
49 
50 	/* handle trivial cases */
51 	if (hx >= 0x406f0000) /* |x| >= 2^112 + ... or x is nan */
52 		return (hx >= 0x7fff0000 ? x + x : x);
53 
54 	/* handle |x| < 1 */
55 	if (hx < 0x3fff0000)
56 		return (sx ? -0.0L : 0.0L);
57 
58 	j = 0x406f - (hx >> 16);		/* 1 <= j <= 112 */
59 	xx.i[0] = hx;
60 	if (j >= 96) {				/* 96 <= j <= 112 */
61 		xx.i[0] &= ~((1 << (j - 96)) - 1);
62 		xx.i[1] = xx.i[2] = xx.i[3] = 0;
63 	} else if (j >= 64) {			/* 64 <= j <= 95 */
64 		xx.i[1] &= ~((1 << (j - 64)) - 1);
65 		xx.i[2] = xx.i[3] = 0;
66 	} else if (j >= 32) {			/* 32 <= j <= 63 */
67 		xx.i[2] &= ~((1 << (j - 32)) - 1);
68 		xx.i[3] = 0;
69 	} else					/* 1 <= j <= 31 */
70 		xx.i[3] &= ~((1 << j) - 1);
71 
72 	/* negate result if need be */
73 	if (sx)
74 		xx.i[0] |= 0x80000000;
75 	return (xx.q);
76 }
77 #elif defined(__x86)
78 long double
79 truncl(long double x) {
80 	union {
81 		unsigned i[3];
82 		long double e;
83 	} xx;
84 	int ex, sx, i;
85 
86 	xx.e = x;
87 	ex = xx.i[2] & 0x7fff;
88 	sx = xx.i[2] & 0x8000;
89 	if (ex < 0x403e) {	/* |x| < 2^63 */
90 		if (ex < 0x3fff)	/* |x| < 1 */
91 			return (sx ? -0.0L : 0.0L);
92 
93 		/* chop x at the integer bit */
94 		if (ex < 0x401e) {
95 			i = 1 << (0x401d - ex);
96 			xx.i[1] &= ~(i | (i - 1));
97 			xx.i[0] = 0;
98 		} else {
99 			i = 1 << (0x403d - ex);
100 			xx.i[0] &= ~(i | (i - 1));
101 		}
102 		return (xx.e);
103 	} else if (ex < 0x7fff)	/* x is integral */
104 		return (x);
105 	else			/* inf or nan */
106 		return (x + x);
107 }
108 #else
109 #error Unknown architecture
110 #endif	/* defined(__sparc) || defined(__x86) */
111