/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * http://www.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is Mozilla Communicator client code, released * March 31, 1998. * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1998 * the Initial Developer. All Rights Reserved. * * Contributor(s): * * Alternatively, the contents of this file may be used under the terms of * either of the GNU General Public License Version 2 or later (the "GPL"), * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ #ifndef jsbit_h___ #define jsbit_h___ #include "jstypes.h" #include "jsutil.h" JS_BEGIN_EXTERN_C /* ** A jsbitmap_t is a long integer that can be used for bitmaps */ typedef JSUword jsbitmap_t; /* NSPR name, a la Unix system types */ typedef jsbitmap_t jsbitmap; /* JS-style scalar typedef name */ #define JS_TEST_BIT(_map,_bit) \ ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] & (1L << ((_bit) & (JS_BITS_PER_WORD-1)))) #define JS_SET_BIT(_map,_bit) \ ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |= (1L << ((_bit) & (JS_BITS_PER_WORD-1)))) #define JS_CLEAR_BIT(_map,_bit) \ ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &= ~(1L << ((_bit) & (JS_BITS_PER_WORD-1)))) /* ** Compute the log of the least power of 2 greater than or equal to n */ extern JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 i); /* ** Compute the log of the greatest power of 2 less than or equal to n */ extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i); /* * Check if __builtin_clz is available which apeared first in GCC 3.4. * The built-in allows to speedup calculations of ceiling/floor log2, * see bug 327129. */ #if __GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) # define JS_HAS_GCC_BUILTIN_CLZ #endif /* ** Macro version of JS_CeilingLog2: Compute the log of the least power of ** 2 greater than or equal to _n. The result is returned in _log2. */ #ifdef JS_HAS_GCC_BUILTIN_CLZ /* * Use __builtin_clz or count-leading-zeros to calculate ceil(log2(_n)). * The macro checks for "n <= 1" and not "n != 0" as __builtin_clz(0) is * undefined. */ # define JS_CEILING_LOG2(_log2,_n) \ JS_BEGIN_MACRO \ JS_STATIC_ASSERT(sizeof(unsigned int) == sizeof(JSUint32)); \ unsigned int j_ = (unsigned int)(_n); \ (_log2) = (j_ <= 1 ? 0 : 32 - __builtin_clz(j_ - 1)); \ JS_END_MACRO #else # define JS_CEILING_LOG2(_log2,_n) \ JS_BEGIN_MACRO \ JSUint32 j_ = (JSUint32)(_n); \ (_log2) = 0; \ if ((j_) & ((j_)-1)) \ (_log2) += 1; \ if ((j_) >> 16) \ (_log2) += 16, (j_) >>= 16; \ if ((j_) >> 8) \ (_log2) += 8, (j_) >>= 8; \ if ((j_) >> 4) \ (_log2) += 4, (j_) >>= 4; \ if ((j_) >> 2) \ (_log2) += 2, (j_) >>= 2; \ if ((j_) >> 1) \ (_log2) += 1; \ JS_END_MACRO #endif /* ** Macro version of JS_FloorLog2: Compute the log of the greatest power of ** 2 less than or equal to _n. The result is returned in _log2. ** ** This is equivalent to finding the highest set bit in the word. */ #if JS_GCC_HAS_BUILTIN_CLZ /* * Use __builtin_clz or count-leading-zeros to calculate floor(log2(_n)). * Since __builtin_clz(0) is undefined, the macro set the loweset bit to 1 * to ensure 0 result when _n == 0. */ # define JS_FLOOR_LOG2(_log2,_n) \ JS_BEGIN_MACRO \ JS_STATIC_ASSERT(sizeof(unsigned int) == sizeof(JSUint32)); \ (_log2) = 31 - __builtin_clz(((unsigned int)(_n)) | 1); \ JS_END_MACRO #else # define JS_FLOOR_LOG2(_log2,_n) \ JS_BEGIN_MACRO \ JSUint32 j_ = (JSUint32)(_n); \ (_log2) = 0; \ if ((j_) >> 16) \ (_log2) += 16, (j_) >>= 16; \ if ((j_) >> 8) \ (_log2) += 8, (j_) >>= 8; \ if ((j_) >> 4) \ (_log2) += 4, (j_) >>= 4; \ if ((j_) >> 2) \ (_log2) += 2, (j_) >>= 2; \ if ((j_) >> 1) \ (_log2) += 1; \ JS_END_MACRO #endif /* * Internal function. * Compute the log of the least power of 2 greater than or equal to n. * This is a version of JS_CeilingLog2 that operates on jsuword with * CPU-dependant size. */ #define JS_CEILING_LOG2W(n) ((n) <= 1 ? 0 : 1 + JS_FLOOR_LOG2W((n) - 1)) /* * Internal function. * Compute the log of the greatest power of 2 less than or equal to n. * This is a version of JS_FloorLog2 that operates on jsuword with * CPU-dependant size and requires that n != 0. */ #define JS_FLOOR_LOG2W(n) (JS_ASSERT((n) != 0), js_FloorLog2wImpl(n)) #ifdef JS_HAS_GCC_BUILTIN_CLZ # if JS_BYTES_PER_WORD == 4 JS_STATIC_ASSERT(sizeof(unsigned) == sizeof(JSUword)); # define js_FloorLog2wImpl(n) \ ((JSUword)(JS_BITS_PER_WORD - 1 - __builtin_clz(n))) # elif JS_BYTES_PER_WORD == 8 JS_STATIC_ASSERT(sizeof(unsigned long long) == sizeof(JSUword)); # define js_FloorLog2wImpl(n) \ ((JSUword)(JS_BITS_PER_WORD - 1 - __builtin_clzll(n))) # else # error "NOT SUPPORTED" # endif #else # if JS_BYTES_PER_WORD == 4 # define js_FloorLog2wImpl(n) ((JSUword)JS_FloorLog2(n)) # elif JS_BYTES_PER_WORD == 8 extern JSUword js_FloorLog2wImpl(JSUword n); # else # error "NOT SUPPORTED" # endif #endif JS_END_EXTERN_C #endif /* jsbit_h___ */