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 ilogbf = __ilogbf 32 #endif 33 34 #include "libm.h" 35 #include "xpg6.h" /* __xpg6 */ 36 37 #if defined(USE_FPSCALE) || defined(__x86) 38 static const float two25 = 33554432.0F; 39 #else 40 /* 41 * v: a non-zero subnormal |x| 42 */ 43 static int 44 ilogbf_subnormal(unsigned v) { 45 int r = -126 - 23; 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(USE_FPSCALE) */ 57 58 static int 59 raise_invalid(int v) { /* SUSv3 requires ilogbf(0,+/-Inf,NaN) raise invalid */ 60 #ifndef lint 61 if ((__xpg6 & _C99SUSv3_ilogb_0InfNaN_raises_invalid) != 0) { 62 static const double zero = 0.0; 63 volatile double dummy; 64 65 dummy = zero / zero; 66 } 67 #endif 68 return (v); 69 } 70 71 int 72 ilogbf(float x) { 73 int k = *((int *) &x) & ~0x80000000; 74 75 if (k < 0x00800000) { 76 if (k == 0) 77 return (raise_invalid(0x80000001)); 78 else { 79 #if defined(USE_FPSCALE) || defined(__x86) 80 x *= two25; 81 return (((*((int *) &x) & 0x7f800000) >> 23) - 152); 82 #else 83 return (ilogbf_subnormal(k)); 84 #endif 85 } 86 } else if (k < 0x7f800000) 87 return ((k >> 23) - 127); 88 else 89 return (raise_invalid(0x7fffffff)); 90 } 91