xref: /titanic_50/usr/src/lib/libm/common/m9x/lrintl.c (revision 89621fe174cf95ae903df6ceab605bf24d696ac3)
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 lrintl = __lrintl
32 #endif
33 
34 #include <sys/isa_defs.h>	/* _ILP32 */
35 #include "libm.h"
36 
37 #if defined(_ILP32)
38 #if defined(__sparc)
39 
40 #include "fma.h"
41 #include "fenv_inlines.h"
42 
43 long
44 lrintl(long double x) {
45 	union {
46 		unsigned int i[4];
47 		long double q;
48 	} xx;
49 	union {
50 		unsigned int i;
51 		float f;
52 	} tt;
53 	unsigned int hx, sx, frac, l, fsr;
54 	int rm, j;
55 	volatile float dummy;
56 
57 	xx.q = x;
58 	sx = xx.i[0] & 0x80000000;
59 	hx = xx.i[0] & ~0x80000000;
60 
61 	/* handle trivial cases */
62 	if (hx > 0x401e0000) { /* |x| > 2^31 + ... or x is nan */
63 		/* convert an out-of-range float */
64 		tt.i = sx | 0x7f000000;
65 		return ((long) tt.f);
66 	} else if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0) /* x is zero */
67 		return (0L);
68 
69 	/* get the rounding mode */
70 	__fenv_getfsr32(&fsr);
71 	rm = fsr >> 30;
72 
73 	/* flip the sense of directed roundings if x is negative */
74 	if (sx)
75 		rm ^= rm >> 1;
76 
77 	/* handle |x| < 1 */
78 	if (hx < 0x3fff0000) {
79 		dummy = 1.0e30F; /* x is nonzero, so raise inexact */
80 		dummy += 1.0e-30F;
81 		if (rm == FSR_RP || (rm == FSR_RN && (hx >= 0x3ffe0000 &&
82 			((hx & 0xffff) | xx.i[1] | xx.i[2] | xx.i[3]))))
83 			return (sx ? -1L : 1L);
84 		return (0L);
85 	}
86 
87 	/* extract the integer and fractional parts of x */
88 	j = 0x406f - (hx >> 16);		/* 91 <= j <= 112 */
89 	xx.i[0] = 0x10000 | (xx.i[0] & 0xffff);
90 	if (j >= 96) {				/* 96 <= j <= 112 */
91 		l = xx.i[0] >> (j - 96);
92 		frac = ((xx.i[0] << 1) << (127 - j)) | (xx.i[1] >> (j - 96));
93 		if (((xx.i[1] << 1) << (127 - j)) | xx.i[2] | xx.i[3])
94 			frac |= 1;
95 	} else {				/* 91 <= j <= 95 */
96 		l = (xx.i[0] << (96 - j)) | (xx.i[1] >> (j - 64));
97 		frac = (xx.i[1] << (96 - j)) | (xx.i[2] >> (j - 64));
98 		if ((xx.i[2] << (96 - j)) | xx.i[3])
99 			frac |= 1;
100 	}
101 
102 	/* round */
103 	if (frac && (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000U ||
104 		(frac == 0x80000000 && (l & 1))))))
105 		l++;
106 
107 	/* check for result out of range (note that z is |x| at this point) */
108 	if (l > 0x80000000U || (l == 0x80000000U && !sx)) {
109 		tt.i = sx | 0x7f000000;
110 		return ((long) tt.f);
111 	}
112 
113 	/* raise inexact if need be */
114 	if (frac) {
115 		dummy = 1.0e30F;
116 		dummy += 1.0e-30F;
117 	}
118 
119 	/* negate result if need be */
120 	if (sx)
121 		l = -l;
122 	return ((long) l);
123 }
124 #elif defined(__x86)
125 long
126 lrintl(long double x) {
127 	/*
128 	 * Note: The following code works on x86 (in the default rounding
129 	 * precision mode), but one ought to just use the fistpl instruction
130 	 * instead.
131 	 */
132 	union {
133 		unsigned i[3];
134 		long double e;
135 	} xx, yy;
136 	int ex;
137 
138 	xx.e = x;
139 	ex = xx.i[2] & 0x7fff;
140 	if (ex < 0x403e) {	/* |x| < 2^63 */
141 		/* add and subtract a power of two to round x to an integer */
142 		yy.i[2] = (xx.i[2] & 0x8000) | 0x403e;
143 		yy.i[1] = 0x80000000;
144 		yy.i[0] = 0;
145 		x = (x + yy.e) - yy.e;
146 	}
147 
148 	/* now x is nan, inf, or integral */
149 	return ((long) x);
150 }
151 #else
152 #error Unknown architecture
153 #endif	/* defined(__sparc) || defined(__x86) */
154 #else
155 #error Unsupported architecture
156 #endif	/* defined(_ILP32) */
157