| /* |
| * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* ilogb(double x) |
| * return the binary exponent of non-zero x |
| * ilogb(0) = 0x80000001 |
| * ilogb(inf/NaN) = 0x7fffffff (no signal is raised) |
| */ |
| |
| #include "fdlibm.h" |
| |
| #ifdef __STDC__ |
| int ilogb(double x) |
| #else |
| int ilogb(x) |
| double x; |
| #endif |
| { |
| int hx,lx,ix; |
| |
| hx = (__HI(x))&0x7fffffff; /* high word of x */ |
| if(hx<0x00100000) { |
| lx = __LO(x); |
| if((hx|lx)==0) |
| return 0x80000001; /* ilogb(0) = 0x80000001 */ |
| else /* subnormal x */ |
| if(hx==0) { |
| for (ix = -1043; lx>0; lx<<=1) ix -=1; |
| } else { |
| for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1; |
| } |
| return ix; |
| } |
| else if (hx<0x7ff00000) return (hx>>20)-1023; |
| else return 0x7fffffff; |
| } |
