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 #if defined(ELFOBJ) 31 #pragma weak scalbnf = __scalbnf 32 #endif 33 34 #include "libm.h" 35 #include <float.h> /* FLT_MAX, FLT_MIN */ 36 #include <stdlib.h> /* abs */ 37 38 static const float twom25f = 2.98023223876953125e-8F; 39 #if defined(USE_FPSCALE) || defined(__x86) 40 static const float two23f = 8388608.0F; 41 #else 42 /* 43 * v: a non-zero subnormal |x|; returns [-22, 0] 44 */ 45 static int 46 ilogbf_biased(unsigned v) { 47 int r = -22; 48 49 if (v & 0xffff0000) 50 r += 16, v >>= 16; 51 if (v & 0xff00) 52 r += 8, v >>= 8; 53 if (v & 0xf0) 54 r += 4, v >>= 4; 55 v <<= 1; 56 return (r + ((0xffffaa50 >> v) & 0x3)); 57 } 58 #endif /* defined(USE_FPSCALE) */ 59 60 float 61 scalbnf(float x, int n) { 62 int *px = (int *) &x, ix, k; 63 64 ix = *px & ~0x80000000; 65 k = ix >> 23; 66 if (k == 0xff) 67 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN) 68 return (ix > 0x7f800000 ? x * x : x); 69 #else 70 return (x + x); 71 #endif 72 if (ix == 0 || n == 0) 73 return (x); 74 if (k == 0) { 75 #if defined(USE_FPSCALE) || defined(__x86) 76 x *= two23f; 77 k = ((*px & ~0x80000000) >> 23) - 23; 78 #else 79 k = ilogbf_biased(ix); 80 *px = (*px & 0x80000000) | (ix << (-k + 1)); 81 #endif 82 } 83 if ((unsigned) abs(n) >= 131072) /* cast to unsigned for -2^31 */ 84 n >>= 1; /* avoid subsequent integer overflow */ 85 k += n; 86 if (k > 0xfe) 87 return (FLT_MAX * copysignf(FLT_MAX, x)); 88 if (k <= -25) 89 return (FLT_MIN * copysignf(FLT_MIN, x)); 90 if (k > 0) { 91 *px = (*px & ~0x7f800000) | (k << 23); 92 return (x); 93 } 94 k += 25; 95 *px = (*px & ~0x7f800000) | (k << 23); 96 return (x * twom25f); 97 } 98