xref: /titanic_52/usr/src/lib/libm/common/Q/rintl.c (revision ddc0e0b53c661f6e439e3b7072b3ef353eadb4af)
125c28e83SPiotr Jasiukajtis /*
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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 __rintl = rintl
3125c28e83SPiotr Jasiukajtis 
3225c28e83SPiotr Jasiukajtis /*
3325c28e83SPiotr Jasiukajtis  * rintl(long double x) return x rounded to integral according to
3425c28e83SPiotr Jasiukajtis  * the prevailing rounding direction
3525c28e83SPiotr Jasiukajtis  *
3625c28e83SPiotr Jasiukajtis  * NOTE: aintl(x), anintl(x), ceill(x), floorl(x), and rintl(x) return result
3725c28e83SPiotr Jasiukajtis  * with the same sign as x's, including 0.0L.
3825c28e83SPiotr Jasiukajtis  */
3925c28e83SPiotr Jasiukajtis 
4025c28e83SPiotr Jasiukajtis #include "libm.h"
4125c28e83SPiotr Jasiukajtis #include "longdouble.h"
4225c28e83SPiotr Jasiukajtis 
4325c28e83SPiotr Jasiukajtis extern enum fp_precision_type __swapRP(enum fp_precision_type);
4425c28e83SPiotr Jasiukajtis 
4525c28e83SPiotr Jasiukajtis static const double one = 1.0;
4625c28e83SPiotr Jasiukajtis static const long double qzero = 0.0L;
4725c28e83SPiotr Jasiukajtis 
4825c28e83SPiotr Jasiukajtis long double
4925c28e83SPiotr Jasiukajtis rintl(long double x) {
5025c28e83SPiotr Jasiukajtis 	enum fp_precision_type rp;
5125c28e83SPiotr Jasiukajtis 	long double t, w, two112;
5225c28e83SPiotr Jasiukajtis 	int *pt = (int *) &two112;
5325c28e83SPiotr Jasiukajtis 
5425c28e83SPiotr Jasiukajtis 	if (!finitel(x))
5525c28e83SPiotr Jasiukajtis 		return (x + x);
5625c28e83SPiotr Jasiukajtis 
5725c28e83SPiotr Jasiukajtis 	if (*(int *) &one != 0) {	/* set two112 = 2^112 */
5825c28e83SPiotr Jasiukajtis 		pt[0] = 0x406f0000;
5925c28e83SPiotr Jasiukajtis 		pt[1] = pt[2] = pt[3] = 0;
6025c28e83SPiotr Jasiukajtis 	} else {
6125c28e83SPiotr Jasiukajtis 		pt[3] = 0x406f0000;
6225c28e83SPiotr Jasiukajtis 		pt[0] = pt[1] = pt[2] = 0;
6325c28e83SPiotr Jasiukajtis 	}
6425c28e83SPiotr Jasiukajtis 
6525c28e83SPiotr Jasiukajtis 	if (fabsl(x) >= two112)
6625c28e83SPiotr Jasiukajtis 		return (x);	/* already an integer */
6725c28e83SPiotr Jasiukajtis 	t = copysignl(two112, x);
6825c28e83SPiotr Jasiukajtis 	rp = __swapRP(fp_extended);	/* make sure precision is long double */
6925c28e83SPiotr Jasiukajtis 	w = x + t;			/* x+sign(x)*2^112 rounded to integer */
7025c28e83SPiotr Jasiukajtis 	(void) __swapRP(rp);		/* restore precision mode */
7125c28e83SPiotr Jasiukajtis 	if (w == t)
7225c28e83SPiotr Jasiukajtis 		return (copysignl(qzero, x));	/* x rounded to zero */
7325c28e83SPiotr Jasiukajtis 	else
7425c28e83SPiotr Jasiukajtis 		return (w - t);
7525c28e83SPiotr Jasiukajtis }
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