xref: /titanic_41/usr/src/lib/libm/common/m9x/llroundl.c (revision a9d3dcd5820128b4f34bf38f447e47aa95c004e8)
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 __llroundl = llroundl
31 #if defined(__sparcv9) || defined(__amd64)
32 #pragma weak lroundl = llroundl
33 #pragma weak __lroundl = llroundl
34 #endif
35 
36 #include "libm.h"
37 
38 #if defined(__sparc)
39 long long
llroundl(long double x)40 llroundl(long double x) {
41 	union {
42 		unsigned i[4];
43 		long double q;
44 	} xx;
45 	union {
46 		unsigned i[2];
47 		long long l;
48 	} zz;
49 	union {
50 		unsigned i;
51 		float f;
52 	} tt;
53 	unsigned hx, sx, frac;
54 	int j;
55 
56 	xx.q = x;
57 	sx = xx.i[0] & 0x80000000;
58 	hx = xx.i[0] & ~0x80000000;
59 
60 	/* handle trivial cases */
61 	if (hx > 0x403e0000) { /* |x| > 2^63 + ... or x is nan */
62 		/* convert an out-of-range float */
63 		tt.i = sx | 0x7f000000;
64 		return ((long long) tt.f);
65 	}
66 
67 	/* handle |x| < 1 */
68 	if (hx < 0x3fff0000) {
69 		if (hx >= 0x3ffe0000)
70 			return (sx ? -1LL : 1LL);
71 		return (0LL);
72 	}
73 
74 	/* extract the integer and fractional parts of x */
75 	j = 0x406f - (hx >> 16);
76 	xx.i[0] = 0x10000 | (xx.i[0] & 0xffff);
77 	if (j >= 96) {
78 		zz.i[0] = 0;
79 		zz.i[1] = xx.i[0] >> (j - 96);
80 		frac = ((xx.i[0] << 1) << (127 - j)) | (xx.i[1] >> (j - 96));
81 		if (((xx.i[1] << 1) << (127 - j)) | xx.i[2] | xx.i[3])
82 			frac |= 1;
83 	} else if (j >= 64) {
84 		zz.i[0] = xx.i[0] >> (j - 64);
85 		zz.i[1] = ((xx.i[0] << 1) << (95 - j)) | (xx.i[1] >> (j - 64));
86 		frac = ((xx.i[1] << 1) << (95 - j)) | (xx.i[2] >> (j - 64));
87 		if (((xx.i[2] << 1) << (95 - j)) | xx.i[3])
88 			frac |= 1;
89 	} else {
90 		zz.i[0] = ((xx.i[0] << 1) << (63 - j)) | (xx.i[1] >> (j - 32));
91 		zz.i[1] = ((xx.i[1] << 1) << (63 - j)) | (xx.i[2] >> (j - 32));
92 		frac = ((xx.i[2] << 1) << (63 - j)) | (xx.i[3] >> (j - 32));
93 		if ((xx.i[3] << 1) << (63 - j))
94 			frac |= 1;
95 	}
96 
97 	/* round */
98 	if (frac >= 0x80000000u) {
99 		if (++zz.i[1] == 0)
100 			zz.i[0]++;
101 	}
102 
103 	/* check for result out of range (note that z is |x| at this point) */
104 	if (zz.i[0] > 0x80000000u || (zz.i[0] == 0x80000000 && (zz.i[1] ||
105 		!sx))) {
106 		tt.i = sx | 0x7f000000;
107 		return ((long long) tt.f);
108 	}
109 
110 	/* negate result if need be */
111 	if (sx) {
112 		zz.i[0] = ~zz.i[0];
113 		zz.i[1] = -zz.i[1];
114 		if (zz.i[1] == 0)
115 			zz.i[0]++;
116 	}
117 
118 	return (zz.l);
119 }
120 #elif defined(__x86)
121 long long
llroundl(long double x)122 llroundl(long double x) {
123 	union {
124 		unsigned i[3];
125 		long double e;
126 	} xx;
127 	int ex, sx, i;
128 
129 	xx.e = x;
130 	ex = xx.i[2] & 0x7fff;
131 	sx = xx.i[2] & 0x8000;
132 
133 	if (ex < 0x403e) { /* |x| < 2^63 */
134 		/* handle |x| < 1 */
135 		if (ex < 0x3fff) {
136 			if (ex >= 0x3ffe)
137 				return (sx ? -1LL : 1LL);
138 			return (0LL);
139 		}
140 
141 		/* round x at the integer bit */
142 		if (ex < 0x401e) {
143 			i = 1 << (0x401d - ex);
144 			xx.i[1] = (xx.i[1] + i) & ~(i | (i - 1));
145 			xx.i[0] = 0;
146 		} else {
147 			i = 1 << (0x403d - ex);
148 			xx.i[0] += i;
149 			if (xx.i[0] < i)
150 				xx.i[1]++;
151 			xx.i[0] &= ~(i | (i - 1));
152 		}
153 		if (xx.i[1] == 0) {
154 			xx.i[2] = sx | ++ex;
155 			xx.i[1] = 0x80000000U;
156 		}
157 	}
158 
159 	/* now x is nan, inf, or integral */
160 	return ((long long) xx.e);
161 }
162 #else
163 #error Unknown architecture
164 #endif
165