/usr/include/js/jsbit.h is in libmozjs185-dev 1.8.5-1.0.0+dfsg-4.3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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/* ***** 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 "jscompat.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_BITMAP_SIZE(bits) (JS_HOWMANY(bits, JS_BITS_PER_WORD) * \
sizeof(jsbitmap))
#define JS_TEST_BIT(_map,_bit) ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] & \
((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1))))
#define JS_SET_BIT(_map,_bit) ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |= \
((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1))))
#define JS_CLEAR_BIT(_map,_bit) ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &= \
~((jsbitmap)1<<((_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);
/*
* Replace bit-scanning code sequences with CPU-specific instructions to
* speedup calculations of ceiling/floor log2.
*
* With GCC 3.4 or later we can use __builtin_clz for that, see bug 327129.
*
* SWS: Added MSVC intrinsic bitscan support. See bugs 349364 and 356856.
*/
#if defined(_WIN32) && (_MSC_VER >= 1300) && (defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64))
unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask);
unsigned char _BitScanReverse(unsigned long * Index, unsigned long Mask);
# pragma intrinsic(_BitScanForward,_BitScanReverse)
__forceinline static int
__BitScanForward32(unsigned int val)
{
unsigned long idx;
_BitScanForward(&idx, (unsigned long)val);
return (int)idx;
}
__forceinline static int
__BitScanReverse32(unsigned int val)
{
unsigned long idx;
_BitScanReverse(&idx, (unsigned long)val);
return (int)(31-idx);
}
# define js_bitscan_ctz32(val) __BitScanForward32(val)
# define js_bitscan_clz32(val) __BitScanReverse32(val)
# define JS_HAS_BUILTIN_BITSCAN32
#if defined(_M_AMD64) || defined(_M_X64)
unsigned char _BitScanForward64(unsigned long * Index, unsigned __int64 Mask);
unsigned char _BitScanReverse64(unsigned long * Index, unsigned __int64 Mask);
# pragma intrinsic(_BitScanForward64,_BitScanReverse64)
__forceinline static int
__BitScanForward64(unsigned __int64 val)
{
unsigned long idx;
_BitScanForward64(&idx, val);
return (int)idx;
}
__forceinline static int
__BitScanReverse64(unsigned __int64 val)
{
unsigned long idx;
_BitScanReverse64(&idx, val);
return (int)(63-idx);
}
# define js_bitscan_ctz64(val) __BitScanForward64(val)
# define js_bitscan_clz64(val) __BitScanReverse64(val)
# define JS_HAS_BUILTIN_BITSCAN64
#endif
#elif (__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
# define js_bitscan_ctz32(val) __builtin_ctz(val)
# define js_bitscan_clz32(val) __builtin_clz(val)
# define JS_HAS_BUILTIN_BITSCAN32
# if (JS_BYTES_PER_WORD == 8)
# define js_bitscan_ctz64(val) __builtin_ctzll(val)
# define js_bitscan_clz64(val) __builtin_clzll(val)
# define JS_HAS_BUILTIN_BITSCAN64
# endif
#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_BUILTIN_BITSCAN32
/*
* Use intrinsic function or count-leading-zeros to calculate ceil(log2(_n)).
* The macro checks for "n <= 1" and not "n != 0" as js_bitscan_clz32(0) is
* undefined.
*/
# define JS_CEILING_LOG2(_log2,_n) \
JS_BEGIN_MACRO \
unsigned int j_ = (unsigned int)(_n); \
(_log2) = (j_ <= 1 ? 0 : 32 - js_bitscan_clz32(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.
*/
#ifdef JS_HAS_BUILTIN_BITSCAN32
/*
* Use js_bitscan_clz32 or count-leading-zeros to calculate floor(log2(_n)).
* Since js_bitscan_clz32(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 \
(_log2) = 31 - js_bitscan_clz32(((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 unsigned integers 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 unsigned integers with
* CPU-dependant size and requires that n != 0.
*/
#define JS_FLOOR_LOG2W(n) (JS_ASSERT((n) != 0), js_FloorLog2wImpl(n))
#if JS_BYTES_PER_WORD == 4
# ifdef JS_HAS_BUILTIN_BITSCAN32
# define js_FloorLog2wImpl(n) \
((size_t)(JS_BITS_PER_WORD - 1 - js_bitscan_clz32(n)))
# else
# define js_FloorLog2wImpl(n) ((size_t)JS_FloorLog2(n))
#endif
#elif JS_BYTES_PER_WORD == 8
# ifdef JS_HAS_BUILTIN_BITSCAN64
# define js_FloorLog2wImpl(n) \
((size_t)(JS_BITS_PER_WORD - 1 - js_bitscan_clz64(n)))
# else
extern size_t js_FloorLog2wImpl(size_t n);
# endif
#else
# error "NOT SUPPORTED"
#endif
namespace js {
inline size_t
CountTrailingZeros(size_t n)
{
JS_ASSERT(n != 0);
#if JS_BYTES_PER_WORD != 4 && JS_BYTES_PER_WORD != 8
# error "NOT SUPPORTED"
#endif
#if JS_BYTES_PER_WORD == 4 && defined JS_HAS_BUILTIN_BITSCAN32
return js_bitscan_ctz32(n);
#elif JS_BYTES_PER_WORD == 8 && defined JS_HAS_BUILTIN_BITSCAN64
return js_bitscan_ctz64(n);
#else
size_t count = 0;
# if JS_BYTES_PER_WORD == 8
if (!(n & size_t(0xFFFFFFFFU))) { count += 32; n >>= 32; }
# endif
if (!(n & 0xFFFF)) { count += 16; n >>= 16; }
if (!(n & 0xFF)) { count += 8; n >>= 8; }
if (!(n & 0xF)) { count += 4; n >>= 4; }
if (!(n & 0x3)) { count += 2; n >>= 2; }
if (!(n & 0x1)) { count += 1; n >>= 1; }
return count + 1 - (n & 0x1);
#endif
}
}
/*
* Macros for rotate left. There is no rotate operation in the C Language so
* the construct (a << 4) | (a >> 28) is used instead. Most compilers convert
* this to a rotate instruction but some versions of MSVC don't without a
* little help. To get MSVC to generate a rotate instruction, we have to use
* the _rotl intrinsic and use a pragma to make _rotl inline.
*
* MSVC in VS2005 will do an inline rotate instruction on the above construct.
*/
#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
defined(_M_X64))
#include <stdlib.h>
#pragma intrinsic(_rotl)
#define JS_ROTATE_LEFT32(a, bits) _rotl(a, bits)
#else
#define JS_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
#endif
JS_END_EXTERN_C
#endif /* jsbit_h___ */
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