/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma weak trunc = __trunc

#include "libm.h"

double
trunc(double x) {
	union {
		unsigned i[2];
		double d;
	} xx;
	unsigned hx, sx, i;

	xx.d = x;
	hx = xx.i[HIWORD] & ~0x80000000;
	sx = xx.i[HIWORD] & 0x80000000;
	if (hx < 0x43300000) {	/* |x| < 2^52 */
		if (hx < 0x3ff00000)	/* |x| < 1 */
			return (sx ? -0.0 : 0.0);

		/* chop x at the integer bit */
		if (hx < 0x41300000) {
			i = 1 << (0x412 - (hx >> 20));
			xx.i[HIWORD] &= ~(i | (i - 1));
			xx.i[LOWORD] = 0;
		} else {
			i = 1 << (0x432 - (hx >> 20));
			xx.i[LOWORD] &= ~(i | (i - 1));
		}
		return (xx.d);
	} else if (hx < 0x7ff00000)
		return (x);
	else
#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
		return (hx >= 0x7ff80000 ? x : x + x);
		/* assumes sparc-like QNaN */
#else
		return (x + x);
#endif
}