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/* -*- 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___ */
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