xref: /onnv-gate/usr/src/lib/libc/sparc/fp/_Q_scl.c (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
24*0Sstevel@tonic-gate  * Use is subject to license terms.
25*0Sstevel@tonic-gate  */
26*0Sstevel@tonic-gate 
27*0Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate #if !defined(sparc) && !defined(__sparc)
30*0Sstevel@tonic-gate #error This code is for SPARC only
31*0Sstevel@tonic-gate #endif
32*0Sstevel@tonic-gate 
33*0Sstevel@tonic-gate /*
34*0Sstevel@tonic-gate  * _Q_scl(x, n) sets *x = *x * 2^n.
35*0Sstevel@tonic-gate  *
36*0Sstevel@tonic-gate  * This routine tacitly assumes the result will be either zero
37*0Sstevel@tonic-gate  * or normal, so there is no need to raise any exceptions.
38*0Sstevel@tonic-gate  */
39*0Sstevel@tonic-gate void
_Q_scl(long double * x,int n)40*0Sstevel@tonic-gate _Q_scl(long double *x, int n)
41*0Sstevel@tonic-gate {
42*0Sstevel@tonic-gate 	union {
43*0Sstevel@tonic-gate 		unsigned int	i[4];
44*0Sstevel@tonic-gate 		long double	q;
45*0Sstevel@tonic-gate 	} xx;
46*0Sstevel@tonic-gate 	int	hx;
47*0Sstevel@tonic-gate 
48*0Sstevel@tonic-gate 	xx.q = *x;
49*0Sstevel@tonic-gate 	hx = xx.i[0] & ~0x80000000;
50*0Sstevel@tonic-gate 
51*0Sstevel@tonic-gate 	if (hx < 0x10000) { /* x is zero or subnormal */
52*0Sstevel@tonic-gate 		if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0)
53*0Sstevel@tonic-gate 			return;
54*0Sstevel@tonic-gate 
55*0Sstevel@tonic-gate 		/* normalize x */
56*0Sstevel@tonic-gate 		while (hx == 0 && xx.i[1] < 0x10000) {
57*0Sstevel@tonic-gate 			hx = xx.i[1];
58*0Sstevel@tonic-gate 			xx.i[1] = xx.i[2];
59*0Sstevel@tonic-gate 			xx.i[2] = xx.i[3];
60*0Sstevel@tonic-gate 			xx.i[3] = 0;
61*0Sstevel@tonic-gate 			n -= 32;
62*0Sstevel@tonic-gate 		}
63*0Sstevel@tonic-gate 		while (hx < 0x10000) {
64*0Sstevel@tonic-gate 			hx = (hx << 1) | (xx.i[1] >> 31);
65*0Sstevel@tonic-gate 			xx.i[1] = (xx.i[1] << 1) | (xx.i[2] >> 31);
66*0Sstevel@tonic-gate 			xx.i[2] = (xx.i[2] << 1) | (xx.i[3] >> 31);
67*0Sstevel@tonic-gate 			xx.i[3] <<= 1;
68*0Sstevel@tonic-gate 			n--;
69*0Sstevel@tonic-gate 		}
70*0Sstevel@tonic-gate 		xx.i[0] = hx | (xx.i[0] & 0x80000000);
71*0Sstevel@tonic-gate 	}
72*0Sstevel@tonic-gate 
73*0Sstevel@tonic-gate 	if ((hx >> 16) + n < 1) {
74*0Sstevel@tonic-gate 		/* for subnormal result, just deliver zero */
75*0Sstevel@tonic-gate 		xx.i[0] = xx.i[0] & 0x80000000;
76*0Sstevel@tonic-gate 		xx.i[1] = xx.i[2] = xx.i[3] = 0;
77*0Sstevel@tonic-gate 	} else
78*0Sstevel@tonic-gate 		xx.i[0] += (n << 16);
79*0Sstevel@tonic-gate 	*x = xx.q;
80*0Sstevel@tonic-gate }
81*0Sstevel@tonic-gate 
82*0Sstevel@tonic-gate static const union {
83*0Sstevel@tonic-gate 	int		i[4];
84*0Sstevel@tonic-gate 	long double	q;
85*0Sstevel@tonic-gate } consts[2] = {
86*0Sstevel@tonic-gate 	{ 0x7ffe0000, 0, 0, 0 },
87*0Sstevel@tonic-gate 	{ 0x00010000, 0, 0, 0 }
88*0Sstevel@tonic-gate };
89*0Sstevel@tonic-gate 
90*0Sstevel@tonic-gate /*
91*0Sstevel@tonic-gate  * _Q_scle(x, n) sets *x = *x * 2^n, raising overflow or underflow
92*0Sstevel@tonic-gate  * as appropriate.
93*0Sstevel@tonic-gate  *
94*0Sstevel@tonic-gate  * This routine tacitly assumes the argument is either zero or normal.
95*0Sstevel@tonic-gate  */
96*0Sstevel@tonic-gate void
_Q_scle(long double * x,int n)97*0Sstevel@tonic-gate _Q_scle(long double *x, int n)
98*0Sstevel@tonic-gate {
99*0Sstevel@tonic-gate 	union {
100*0Sstevel@tonic-gate 		unsigned int	i[4];
101*0Sstevel@tonic-gate 		long double	q;
102*0Sstevel@tonic-gate 	} xx;
103*0Sstevel@tonic-gate 	int	hx;
104*0Sstevel@tonic-gate 
105*0Sstevel@tonic-gate 	xx.q = *x;
106*0Sstevel@tonic-gate 	hx = (xx.i[0] >> 16) & 0x7fff;
107*0Sstevel@tonic-gate 
108*0Sstevel@tonic-gate 	if (hx == 0) /* x must be zero */
109*0Sstevel@tonic-gate 		return;
110*0Sstevel@tonic-gate 
111*0Sstevel@tonic-gate 	hx += n;
112*0Sstevel@tonic-gate 	if (hx >= 0x7fff) { /* overflow */
113*0Sstevel@tonic-gate 		xx.i[0] = 0x7ffe0000 | (xx.i[0] & 0x80000000);
114*0Sstevel@tonic-gate 		xx.i[1] = xx.i[2] = xx.i[3] = 0;
115*0Sstevel@tonic-gate 		xx.q *= consts[0].q;
116*0Sstevel@tonic-gate 	} else if (hx < 1) { /* possible underflow */
117*0Sstevel@tonic-gate 		if (hx < -112) {
118*0Sstevel@tonic-gate 			xx.i[0] = 0x00010000 | (xx.i[0] & 0x80000000);
119*0Sstevel@tonic-gate 			xx.i[1] = xx.i[2] = xx.i[3] = 0;
120*0Sstevel@tonic-gate 		} else {
121*0Sstevel@tonic-gate 			xx.i[0] = (0x3ffe0000 + (hx << 16)) |
122*0Sstevel@tonic-gate 				(xx.i[0] & 0x8000ffff);
123*0Sstevel@tonic-gate 		}
124*0Sstevel@tonic-gate 		xx.q *= consts[1].q;
125*0Sstevel@tonic-gate 	} else
126*0Sstevel@tonic-gate 		xx.i[0] += (n << 16);
127*0Sstevel@tonic-gate 
128*0Sstevel@tonic-gate 	*x = xx.q;
129*0Sstevel@tonic-gate }
130