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 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
2325c28e83SPiotr Jasiukajtis */
2425c28e83SPiotr Jasiukajtis /*
2525c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
2625c28e83SPiotr Jasiukajtis * Use is subject to license terms.
2725c28e83SPiotr Jasiukajtis */
2825c28e83SPiotr Jasiukajtis
29*ddc0e0b5SRichard Lowe #pragma weak __scalbn = scalbn
3025c28e83SPiotr Jasiukajtis
3125c28e83SPiotr Jasiukajtis #include "libm.h"
3225c28e83SPiotr Jasiukajtis
3325c28e83SPiotr Jasiukajtis static const double
3425c28e83SPiotr Jasiukajtis one = 1.0,
3525c28e83SPiotr Jasiukajtis huge = 1.0e300,
3625c28e83SPiotr Jasiukajtis tiny = 1.0e-300,
3725c28e83SPiotr Jasiukajtis twom54 = 5.5511151231257827021181583404541015625e-17;
3825c28e83SPiotr Jasiukajtis
391ec68d33SRichard Lowe #if defined(__x86)
4025c28e83SPiotr Jasiukajtis static const double two52 = 4503599627370496.0;
4125c28e83SPiotr Jasiukajtis #else
4225c28e83SPiotr Jasiukajtis /*
4325c28e83SPiotr Jasiukajtis * Normalize non-zero subnormal x and return biased exponent of x in [-51,0]
4425c28e83SPiotr Jasiukajtis */
4525c28e83SPiotr Jasiukajtis static int
ilogb_biased(unsigned * px)4625c28e83SPiotr Jasiukajtis ilogb_biased(unsigned *px) {
4725c28e83SPiotr Jasiukajtis int s = 52;
4825c28e83SPiotr Jasiukajtis unsigned v = px[HIWORD] & ~0x80000000, w = px[LOWORD], t = v;
4925c28e83SPiotr Jasiukajtis
5025c28e83SPiotr Jasiukajtis if (t)
5125c28e83SPiotr Jasiukajtis s -= 32;
5225c28e83SPiotr Jasiukajtis else
5325c28e83SPiotr Jasiukajtis t = w;
5425c28e83SPiotr Jasiukajtis if (t & 0xffff0000)
5525c28e83SPiotr Jasiukajtis s -= 16, t >>= 16;
5625c28e83SPiotr Jasiukajtis if (t & 0xff00)
5725c28e83SPiotr Jasiukajtis s -= 8, t >>= 8;
5825c28e83SPiotr Jasiukajtis if (t & 0xf0)
5925c28e83SPiotr Jasiukajtis s -= 4, t >>= 4;
6025c28e83SPiotr Jasiukajtis t <<= 1;
6125c28e83SPiotr Jasiukajtis s -= (0xffffaa50 >> t) & 0x3;
6225c28e83SPiotr Jasiukajtis if (s < 32) {
6325c28e83SPiotr Jasiukajtis v = (v << s) | w >> (32 - s);
6425c28e83SPiotr Jasiukajtis w <<= s;
6525c28e83SPiotr Jasiukajtis } else {
6625c28e83SPiotr Jasiukajtis v = w << (s - 32);
6725c28e83SPiotr Jasiukajtis w = 0;
6825c28e83SPiotr Jasiukajtis }
6925c28e83SPiotr Jasiukajtis px[HIWORD] = (px[HIWORD] & 0x80000000) | v;
7025c28e83SPiotr Jasiukajtis px[LOWORD] = w;
7125c28e83SPiotr Jasiukajtis return (1 - s);
7225c28e83SPiotr Jasiukajtis }
731ec68d33SRichard Lowe #endif /* defined(__x86) */
7425c28e83SPiotr Jasiukajtis
7525c28e83SPiotr Jasiukajtis double
scalbn(double x,int n)7625c28e83SPiotr Jasiukajtis scalbn(double x, int n) {
7725c28e83SPiotr Jasiukajtis int *px, ix, hx, k;
7825c28e83SPiotr Jasiukajtis
7925c28e83SPiotr Jasiukajtis px = (int *)&x;
8025c28e83SPiotr Jasiukajtis ix = px[HIWORD];
8125c28e83SPiotr Jasiukajtis hx = ix & ~0x80000000;
8225c28e83SPiotr Jasiukajtis k = hx >> 20;
8325c28e83SPiotr Jasiukajtis
8425c28e83SPiotr Jasiukajtis if (k == 0x7ff) /* x is inf or NaN */
8525c28e83SPiotr Jasiukajtis return (x * one);
8625c28e83SPiotr Jasiukajtis
8725c28e83SPiotr Jasiukajtis if (k == 0) {
8825c28e83SPiotr Jasiukajtis if ((hx | px[LOWORD]) == 0 || n == 0)
8925c28e83SPiotr Jasiukajtis return (x);
901ec68d33SRichard Lowe #if defined(__x86)
9125c28e83SPiotr Jasiukajtis x *= two52;
9225c28e83SPiotr Jasiukajtis ix = px[HIWORD];
9325c28e83SPiotr Jasiukajtis k = ((ix & ~0x80000000) >> 20) - 52;
9425c28e83SPiotr Jasiukajtis #else
9525c28e83SPiotr Jasiukajtis k = ilogb_biased((unsigned *)px);
9625c28e83SPiotr Jasiukajtis ix = px[HIWORD];
9725c28e83SPiotr Jasiukajtis #endif
9825c28e83SPiotr Jasiukajtis /* now k is in the range -51..0 */
9925c28e83SPiotr Jasiukajtis k += n;
10025c28e83SPiotr Jasiukajtis if (k > n) /* integer overflow occurred */
10125c28e83SPiotr Jasiukajtis k = -100;
10225c28e83SPiotr Jasiukajtis } else {
10325c28e83SPiotr Jasiukajtis /* k is in the range 1..1023 */
10425c28e83SPiotr Jasiukajtis k += n;
10525c28e83SPiotr Jasiukajtis if (k < n) /* integer overflow occurred */
10625c28e83SPiotr Jasiukajtis k = 0x7ff;
10725c28e83SPiotr Jasiukajtis }
10825c28e83SPiotr Jasiukajtis
10925c28e83SPiotr Jasiukajtis if (k > 0x7fe)
11025c28e83SPiotr Jasiukajtis return (huge * ((ix < 0)? -huge : huge));
11125c28e83SPiotr Jasiukajtis if (k < 1) {
11225c28e83SPiotr Jasiukajtis if (k <= -54)
11325c28e83SPiotr Jasiukajtis return (tiny * ((ix < 0)? -tiny : tiny));
11425c28e83SPiotr Jasiukajtis k += 54;
11525c28e83SPiotr Jasiukajtis px[HIWORD] = (ix & ~0x7ff00000) | (k << 20);
11625c28e83SPiotr Jasiukajtis return (x * twom54);
11725c28e83SPiotr Jasiukajtis }
11825c28e83SPiotr Jasiukajtis px[HIWORD] = (ix & ~0x7ff00000) | (k << 20);
11925c28e83SPiotr Jasiukajtis return (x);
12025c28e83SPiotr Jasiukajtis }
121