1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #pragma weak __scalblnf = scalblnf 31 32 #include "libm.h" 33 #include <float.h> /* FLT_MAX, FLT_MIN */ 34 35 static const float twom25f = 2.98023223876953125e-8F; 36 #if defined(__x86) 37 static const float two23f = 8388608.0F; 38 #else 39 /* 40 * v: a non-zero subnormal |x|; returns [-22, 0] 41 */ 42 static int 43 ilogbf_biased(unsigned v) { 44 int r = -22; 45 46 if (v & 0xffff0000) 47 r += 16, v >>= 16; 48 if (v & 0xff00) 49 r += 8, v >>= 8; 50 if (v & 0xf0) 51 r += 4, v >>= 4; 52 v <<= 1; 53 return (r + ((0xffffaa50 >> v) & 0x3)); 54 } 55 #endif /* defined(__x86) */ 56 57 float 58 scalblnf(float x, long n) { 59 int *px = (int *) &x, ix, k; 60 61 ix = *px & ~0x80000000; 62 k = ix >> 23; 63 if (k == 0xff) 64 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN) 65 return (ix > 0x7f800000 ? x * x : x); 66 #else 67 return (x + x); 68 #endif 69 if (ix == 0 || n == 0) 70 return (x); 71 if (k == 0) { 72 #if defined(__x86) 73 x *= two23f; 74 k = ((*px & ~0x80000000) >> 23) - 23; 75 #else 76 k = ilogbf_biased(ix); 77 *px = (*px & 0x80000000) | (ix << (-k + 1)); 78 #endif 79 } 80 k += (int) n; 81 if (n > 5000 || k > 0xfe) 82 return (FLT_MAX * copysignf(FLT_MAX, x)); 83 if (n < -5000 || k <= -25) 84 return (FLT_MIN * copysignf(FLT_MIN, x)); 85 if (k > 0) { 86 *px = (*px & ~0x7f800000) | (k << 23); 87 return (x); 88 } 89 k += 25; 90 *px = (*px & ~0x7f800000) | (k << 23); 91 return (x * twom25f); 92 } 93