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/*
* 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 scalbnf = __scalbnf
#include "libm.h"
#include <float.h> /* FLT_MAX, FLT_MIN */
#include <stdlib.h> /* abs */
static const float twom25f = 2.98023223876953125e-8F;
#if defined(__x86)
static const float two23f = 8388608.0F;
#else
/*
* v: a non-zero subnormal |x|; returns [-22, 0]
*/
static int
ilogbf_biased(unsigned v) {
int r = -22;
if (v & 0xffff0000)
r += 16, v >>= 16;
if (v & 0xff00)
r += 8, v >>= 8;
if (v & 0xf0)
r += 4, v >>= 4;
v <<= 1;
return (r + ((0xffffaa50 >> v) & 0x3));
}
#endif /* defined(__x86) */
float
scalbnf(float x, int n) {
int *px = (int *) &x, ix, k;
ix = *px & ~0x80000000;
k = ix >> 23;
if (k == 0xff)
#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
return (ix > 0x7f800000 ? x * x : x);
#else
return (x + x);
#endif
if (ix == 0 || n == 0)
return (x);
if (k == 0) {
#if defined(__x86)
x *= two23f;
k = ((*px & ~0x80000000) >> 23) - 23;
#else
k = ilogbf_biased(ix);
*px = (*px & 0x80000000) | (ix << (-k + 1));
#endif
}
if ((unsigned) abs(n) >= 131072) /* cast to unsigned for -2^31 */
n >>= 1; /* avoid subsequent integer overflow */
k += n;
if (k > 0xfe)
return (FLT_MAX * copysignf(FLT_MAX, x));
if (k <= -25)
return (FLT_MIN * copysignf(FLT_MIN, x));
if (k > 0) {
*px = (*px & ~0x7f800000) | (k << 23);
return (x);
}
k += 25;
*px = (*px & ~0x7f800000) | (k << 23);
return (x * twom25f);
}
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