xref: /titanic_51/usr/src/lib/libm/common/m9x/lround.c (revision ddc0e0b53c661f6e439e3b7072b3ef353eadb4af)
125c28e83SPiotr Jasiukajtis /*
225c28e83SPiotr Jasiukajtis  * CDDL HEADER START
325c28e83SPiotr Jasiukajtis  *
425c28e83SPiotr Jasiukajtis  * The contents of this file are subject to the terms of the
525c28e83SPiotr Jasiukajtis  * Common Development and Distribution License (the "License").
625c28e83SPiotr Jasiukajtis  * You may not use this file except in compliance with the License.
725c28e83SPiotr Jasiukajtis  *
825c28e83SPiotr Jasiukajtis  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
925c28e83SPiotr Jasiukajtis  * or http://www.opensolaris.org/os/licensing.
1025c28e83SPiotr Jasiukajtis  * See the License for the specific language governing permissions
1125c28e83SPiotr Jasiukajtis  * and limitations under the License.
1225c28e83SPiotr Jasiukajtis  *
1325c28e83SPiotr Jasiukajtis  * When distributing Covered Code, include this CDDL HEADER in each
1425c28e83SPiotr Jasiukajtis  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
1525c28e83SPiotr Jasiukajtis  * If applicable, add the following below this CDDL HEADER, with the
1625c28e83SPiotr Jasiukajtis  * fields enclosed by brackets "[]" replaced with your own identifying
1725c28e83SPiotr Jasiukajtis  * information: Portions Copyright [yyyy] [name of copyright owner]
1825c28e83SPiotr Jasiukajtis  *
1925c28e83SPiotr Jasiukajtis  * CDDL HEADER END
2025c28e83SPiotr Jasiukajtis  */
2125c28e83SPiotr Jasiukajtis 
2225c28e83SPiotr Jasiukajtis /*
2325c28e83SPiotr Jasiukajtis  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
2425c28e83SPiotr Jasiukajtis  */
2525c28e83SPiotr Jasiukajtis /*
2625c28e83SPiotr Jasiukajtis  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
2725c28e83SPiotr Jasiukajtis  * Use is subject to license terms.
2825c28e83SPiotr Jasiukajtis  */
2925c28e83SPiotr Jasiukajtis 
30*ddc0e0b5SRichard Lowe #pragma weak __lround = lround
3125c28e83SPiotr Jasiukajtis 
3225c28e83SPiotr Jasiukajtis /*
3325c28e83SPiotr Jasiukajtis  * lround(x) rounds its argument to the nearest integer, rounding ties
3425c28e83SPiotr Jasiukajtis  * away from zero, and converts the result to a 32 bit signed integer.
3525c28e83SPiotr Jasiukajtis  *
3625c28e83SPiotr Jasiukajtis  * If x is NaN, infinite, or so large that the nearest integer
3725c28e83SPiotr Jasiukajtis  * would exceed 32 bits, the invalid operation exception is raised.
3825c28e83SPiotr Jasiukajtis  */
3925c28e83SPiotr Jasiukajtis 
4025c28e83SPiotr Jasiukajtis #include <sys/isa_defs.h>	/* _ILP32 */
4125c28e83SPiotr Jasiukajtis #include "libm.h"
4225c28e83SPiotr Jasiukajtis 
4325c28e83SPiotr Jasiukajtis #if defined(_ILP32)
4425c28e83SPiotr Jasiukajtis long
4525c28e83SPiotr Jasiukajtis lround(double x) {
4625c28e83SPiotr Jasiukajtis 	union {
4725c28e83SPiotr Jasiukajtis 		unsigned i[2];
4825c28e83SPiotr Jasiukajtis 		double d;
4925c28e83SPiotr Jasiukajtis 	} xx;
5025c28e83SPiotr Jasiukajtis 	unsigned hx, sx, i;
5125c28e83SPiotr Jasiukajtis 
5225c28e83SPiotr Jasiukajtis 	xx.d = x;
5325c28e83SPiotr Jasiukajtis 	hx = xx.i[HIWORD] & ~0x80000000;
5425c28e83SPiotr Jasiukajtis 	sx = xx.i[HIWORD] & 0x80000000;
5525c28e83SPiotr Jasiukajtis 	if (hx < 0x43300000) {	/* |x| < 2^52 */
5625c28e83SPiotr Jasiukajtis 		if (hx < 0x3ff00000) {	/* |x| < 1 */
5725c28e83SPiotr Jasiukajtis 			if (hx >= 0x3fe00000)
5825c28e83SPiotr Jasiukajtis 				return (sx ? -1L : 1L);
5925c28e83SPiotr Jasiukajtis 			return (0L);
6025c28e83SPiotr Jasiukajtis 		}
6125c28e83SPiotr Jasiukajtis 
6225c28e83SPiotr Jasiukajtis 		/* round x at the integer bit */
6325c28e83SPiotr Jasiukajtis 		if (hx < 0x41300000) {
6425c28e83SPiotr Jasiukajtis 			i = 1 << (0x412 - (hx >> 20));
6525c28e83SPiotr Jasiukajtis 			xx.i[HIWORD] = (xx.i[HIWORD] + i) & ~(i | (i - 1));
6625c28e83SPiotr Jasiukajtis 			xx.i[LOWORD] = 0;
6725c28e83SPiotr Jasiukajtis 		} else {
6825c28e83SPiotr Jasiukajtis 			i = 1 << (0x432 - (hx >> 20));
6925c28e83SPiotr Jasiukajtis 			xx.i[LOWORD] += i;
7025c28e83SPiotr Jasiukajtis 			if (xx.i[LOWORD] < i)
7125c28e83SPiotr Jasiukajtis 				xx.i[HIWORD]++;
7225c28e83SPiotr Jasiukajtis 			xx.i[LOWORD] &= ~(i | (i - 1));
7325c28e83SPiotr Jasiukajtis 		}
7425c28e83SPiotr Jasiukajtis 	}
7525c28e83SPiotr Jasiukajtis 
7625c28e83SPiotr Jasiukajtis 	/* now x is nan, inf, or integral */
7725c28e83SPiotr Jasiukajtis 	return ((long) xx.d);
7825c28e83SPiotr Jasiukajtis }
7925c28e83SPiotr Jasiukajtis #else
8025c28e83SPiotr Jasiukajtis #error Unsupported architecture
8125c28e83SPiotr Jasiukajtis #endif	/* defined(_ILP32) */
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