diff options
Diffstat (limited to 'third_party/js-1.7/jsbit.h')
| -rw-r--r-- | third_party/js-1.7/jsbit.h | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/third_party/js-1.7/jsbit.h b/third_party/js-1.7/jsbit.h new file mode 100644 index 0000000..87bb047 --- /dev/null +++ b/third_party/js-1.7/jsbit.h @@ -0,0 +1,195 @@ +/* -*- 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___ */ |