xref: /illumos-gate/usr/src/lib/libm/common/m9x/truncl.c (revision ddc0e0b5)

/*
 * 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 __truncl = truncl

#include "libm.h"

#if defined(__sparc)
long double
truncl(long double x) {
	union {
		unsigned i[4];
		long double q;
	} xx;
	unsigned hx, sx;
	int j;

	xx.q = x;
	sx = xx.i[0] & 0x80000000;
	hx = xx.i[0] & ~0x80000000;

	/* handle trivial cases */
	if (hx >= 0x406f0000) /* |x| >= 2^112 + ... or x is nan */
		return (hx >= 0x7fff0000 ? x + x : x);

	/* handle |x| < 1 */
	if (hx < 0x3fff0000)
		return (sx ? -0.0L : 0.0L);

	j = 0x406f - (hx >> 16);		/* 1 <= j <= 112 */
	xx.i[0] = hx;
	if (j >= 96) {				/* 96 <= j <= 112 */
		xx.i[0] &= ~((1 << (j - 96)) - 1);
		xx.i[1] = xx.i[2] = xx.i[3] = 0;
	} else if (j >= 64) {			/* 64 <= j <= 95 */
		xx.i[1] &= ~((1 << (j - 64)) - 1);
		xx.i[2] = xx.i[3] = 0;
	} else if (j >= 32) {			/* 32 <= j <= 63 */
		xx.i[2] &= ~((1 << (j - 32)) - 1);
		xx.i[3] = 0;
	} else					/* 1 <= j <= 31 */
		xx.i[3] &= ~((1 << j) - 1);

	/* negate result if need be */
	if (sx)
		xx.i[0] |= 0x80000000;
	return (xx.q);
}
#elif defined(__x86)
long double
truncl(long double x) {
	union {
		unsigned i[3];
		long double e;
	} xx;
	int ex, sx, i;

	xx.e = x;
	ex = xx.i[2] & 0x7fff;
	sx = xx.i[2] & 0x8000;
	if (ex < 0x403e) {	/* |x| < 2^63 */
		if (ex < 0x3fff)	/* |x| < 1 */
			return (sx ? -0.0L : 0.0L);

		/* chop x at the integer bit */
		if (ex < 0x401e) {
			i = 1 << (0x401d - ex);
			xx.i[1] &= ~(i | (i - 1));
			xx.i[0] = 0;
		} else {
			i = 1 << (0x403d - ex);
			xx.i[0] &= ~(i | (i - 1));
		}
		return (xx.e);
	} else if (ex < 0x7fff)	/* x is integral */
		return (x);
	else			/* inf or nan */
		return (x + x);
}
#else
#error Unknown architecture
#endif	/* defined(__sparc) || defined(__x86) */