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 __scalbnf = scalbnf 31 32 #include "libm.h" 33 #include <float.h> /* FLT_MAX, FLT_MIN */ 34 #include <stdlib.h> /* abs */ 35 36 static const float twom25f = 2.98023223876953125e-8F; 37 #if defined(__x86) 38 static const float two23f = 8388608.0F; 39 #else 40 /* 41 * v: a non-zero subnormal |x|; returns [-22, 0] 42 */ 43 static int 44 ilogbf_biased(unsigned v) { 45 int r = -22; 46 47 if (v & 0xffff0000) 48 r += 16, v >>= 16; 49 if (v & 0xff00) 50 r += 8, v >>= 8; 51 if (v & 0xf0) 52 r += 4, v >>= 4; 53 v <<= 1; 54 return (r + ((0xffffaa50 >> v) & 0x3)); 55 } 56 #endif /* defined(__x86) */ 57 58 float 59 scalbnf(float x, int n) { 60 int *px = (int *) &x, ix, k; 61 62 ix = *px & ~0x80000000; 63 k = ix >> 23; 64 if (k == 0xff) 65 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN) 66 return (ix > 0x7f800000 ? x * x : x); 67 #else 68 return (x + x); 69 #endif 70 if (ix == 0 || n == 0) 71 return (x); 72 if (k == 0) { 73 #if defined(__x86) 74 x *= two23f; 75 k = ((*px & ~0x80000000) >> 23) - 23; 76 #else 77 k = ilogbf_biased(ix); 78 *px = (*px & 0x80000000) | (ix << (-k + 1)); 79 #endif 80 } 81 if ((unsigned) abs(n) >= 131072) /* cast to unsigned for -2^31 */ 82 n >>= 1; /* avoid subsequent integer overflow */ 83 k += n; 84 if (k > 0xfe) 85 return (FLT_MAX * copysignf(FLT_MAX, x)); 86 if (k <= -25) 87 return (FLT_MIN * copysignf(FLT_MIN, x)); 88 if (k > 0) { 89 *px = (*px & ~0x7f800000) | (k << 23); 90 return (x); 91 } 92 k += 25; 93 *px = (*px & ~0x7f800000) | (k << 23); 94 return (x * twom25f); 95 } 96