#### /js/lib/Socket.IO-node/support/expresso/deps/jscoverage/js/jslog2.cpp

C++ | 94 lines | 36 code | 11 blank | 47 comment | 13 complexity | 7d9741b11f97c6ef5cf1caeab2bdd399 MD5 | raw file

Possible License(s): GPL-2.0, LGPL-2.1, MPL-2.0-no-copyleft-exception, BSD-3-Clause

1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ 2/* ***** BEGIN LICENSE BLOCK ***** 3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1 4 * 5 * The contents of this file are subject to the Mozilla Public License Version 6 * 1.1 (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * http://www.mozilla.org/MPL/ 9 * 10 * Software distributed under the License is distributed on an "AS IS" basis, 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 12 * for the specific language governing rights and limitations under the 13 * License. 14 * 15 * The Original Code is Mozilla Communicator client code, released 16 * March 31, 1998. 17 * 18 * The Initial Developer of the Original Code is 19 * Netscape Communications Corporation. 20 * Portions created by the Initial Developer are Copyright (C) 1998 21 * the Initial Developer. All Rights Reserved. 22 * 23 * Contributor(s): 24 * 25 * Alternatively, the contents of this file may be used under the terms of 26 * either of the GNU General Public License Version 2 or later (the "GPL"), 27 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), 28 * in which case the provisions of the GPL or the LGPL are applicable instead 29 * of those above. If you wish to allow use of your version of this file only 30 * under the terms of either the GPL or the LGPL, and not to allow others to 31 * use your version of this file under the terms of the MPL, indicate your 32 * decision by deleting the provisions above and replace them with the notice 33 * and other provisions required by the GPL or the LGPL. If you do not delete 34 * the provisions above, a recipient may use your version of this file under 35 * the terms of any one of the MPL, the GPL or the LGPL. 36 * 37 * ***** END LICENSE BLOCK ***** */ 38 39#include "jsstddef.h" 40#include "jsbit.h" 41#include "jsutil.h" 42 43/* 44** Compute the log of the least power of 2 greater than or equal to n 45*/ 46JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 n) 47{ 48 JSIntn log2; 49 50 JS_CEILING_LOG2(log2, n); 51 return log2; 52} 53 54/* 55** Compute the log of the greatest power of 2 less than or equal to n. 56** This really just finds the highest set bit in the word. 57*/ 58JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 n) 59{ 60 JSIntn log2; 61 62 JS_FLOOR_LOG2(log2, n); 63 return log2; 64} 65 66/* 67 * js_FloorLog2wImpl has to be defined only for 64-bit non-GCC case. 68 */ 69#if !defined(JS_HAS_BUILTIN_BITSCAN64) && JS_BYTES_PER_WORD == 8 70 71JSUword 72js_FloorLog2wImpl(JSUword n) 73{ 74 JSUword log2, m; 75 76 JS_ASSERT(n != 0); 77 78 log2 = 0; 79 m = n >> 32; 80 if (m != 0) { n = m; log2 = 32; } 81 m = n >> 16; 82 if (m != 0) { n = m; log2 |= 16; } 83 m = n >> 8; 84 if (m != 0) { n = m; log2 |= 8; } 85 m = n >> 4; 86 if (m != 0) { n = m; log2 |= 4; } 87 m = n >> 2; 88 if (m != 0) { n = m; log2 |= 2; } 89 log2 |= (n >> 1); 90 91 return log2; 92} 93 94#endif