зеркало из https://github.com/mozilla/gecko-dev.git
180 строки
6.6 KiB
C
180 строки
6.6 KiB
C
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is the Netscape Portable Runtime (NSPR).
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998-2000
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef prbit_h___
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#define prbit_h___
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#include "prtypes.h"
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PR_BEGIN_EXTERN_C
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/* replace compare/jump/add/shift sequence with x86 BSF/BSR instruction */
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#if defined(_WIN32) && (_MSC_VER >= 1300) && (defined(_M_IX86) || defined(_M_AMD64))
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unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask);
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unsigned char _BitScanReverse(unsigned long * Index, unsigned long Mask);
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# pragma intrinsic(_BitScanForward,_BitScanReverse)
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__forceinline static int __prBitScanForward32(unsigned int val)
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{
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unsigned long idx;
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_BitScanForward(&idx, (unsigned long)val);
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return( (int)idx );
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}
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__forceinline static int __prBitScanReverse32(unsigned int val)
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{
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unsigned long idx;
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_BitScanReverse(&idx, (unsigned long)val);
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return( (int)(31-idx) );
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}
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# define pr_bitscan_ctz32(val) __prBitScanForward32(val)
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# define pr_bitscan_clz32(val) __prBitScanReverse32(val)
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# define PR_HAVE_BUILTIN_BITSCAN32
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#elif ((__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) && \
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(defined(__i386__) || defined(__x86_64__))
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# define pr_bitscan_ctz32(val) __builtin_ctz(val)
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# define pr_bitscan_clz32(val) __builtin_clz(val)
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# define PR_HAVE_BUILTIN_BITSCAN32
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#endif /* MSVC || GCC */
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/*
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** A prbitmap_t is a long integer that can be used for bitmaps
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*/
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typedef unsigned long prbitmap_t;
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#define PR_TEST_BIT(_map,_bit) \
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((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
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#define PR_SET_BIT(_map,_bit) \
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((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
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#define PR_CLEAR_BIT(_map,_bit) \
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((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1))))
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/*
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** Compute the log of the least power of 2 greater than or equal to n
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*/
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NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i);
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/*
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** Compute the log of the greatest power of 2 less than or equal to n
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*/
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NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i);
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/*
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** Macro version of PR_CeilingLog2: Compute the log of the least power of
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** 2 greater than or equal to _n. The result is returned in _log2.
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*/
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#ifdef PR_HAVE_BUILTIN_BITSCAN32
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#define PR_CEILING_LOG2(_log2,_n) \
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PR_BEGIN_MACRO \
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PRUint32 j_ = (PRUint32)(_n); \
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(_log2) = (j_ <= 1 ? 0 : 32 - pr_bitscan_clz32(j_ - 1)); \
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PR_END_MACRO
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#else
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#define PR_CEILING_LOG2(_log2,_n) \
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PR_BEGIN_MACRO \
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PRUint32 j_ = (PRUint32)(_n); \
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(_log2) = 0; \
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if ((j_) & ((j_)-1)) \
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(_log2) += 1; \
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if ((j_) >> 16) \
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(_log2) += 16, (j_) >>= 16; \
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if ((j_) >> 8) \
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(_log2) += 8, (j_) >>= 8; \
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if ((j_) >> 4) \
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(_log2) += 4, (j_) >>= 4; \
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if ((j_) >> 2) \
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(_log2) += 2, (j_) >>= 2; \
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if ((j_) >> 1) \
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(_log2) += 1; \
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PR_END_MACRO
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#endif /* PR_HAVE_BUILTIN_BITSCAN32 */
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/*
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** Macro version of PR_FloorLog2: Compute the log of the greatest power of
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** 2 less than or equal to _n. The result is returned in _log2.
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**
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** This is equivalent to finding the highest set bit in the word.
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*/
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#ifdef PR_HAVE_BUILTIN_BITSCAN32
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#define PR_FLOOR_LOG2(_log2,_n) \
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PR_BEGIN_MACRO \
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PRUint32 j_ = (PRUint32)(_n); \
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(_log2) = 31 - pr_bitscan_clz32((j_) | 1); \
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PR_END_MACRO
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#else
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#define PR_FLOOR_LOG2(_log2,_n) \
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PR_BEGIN_MACRO \
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PRUint32 j_ = (PRUint32)(_n); \
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(_log2) = 0; \
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if ((j_) >> 16) \
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(_log2) += 16, (j_) >>= 16; \
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if ((j_) >> 8) \
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(_log2) += 8, (j_) >>= 8; \
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if ((j_) >> 4) \
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(_log2) += 4, (j_) >>= 4; \
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if ((j_) >> 2) \
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(_log2) += 2, (j_) >>= 2; \
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if ((j_) >> 1) \
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(_log2) += 1; \
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PR_END_MACRO
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#endif /* PR_HAVE_BUILTIN_BITSCAN32 */
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/*
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** Macros for rotate left and right. The argument 'a' must be an unsigned
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** 32-bit integer type such as PRUint32.
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**
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** There is no rotate operation in the C Language, so the construct
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** (a << 4) | (a >> 28) is frequently used instead. Most compilers convert
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** this to a rotate instruction, but MSVC doesn't without a little help.
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** To get MSVC to generate a rotate instruction, we have to use the _rotl
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** or _rotr intrinsic and use a pragma to make it inline.
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**
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** Note: MSVC in VS2005 will do an inline rotate instruction on the above
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** construct.
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*/
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#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
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defined(_M_X64))
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#include <stdlib.h>
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#pragma intrinsic(_rotl, _rotr)
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#define PR_ROTATE_LEFT32(a, bits) _rotl(a, bits)
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#define PR_ROTATE_RIGHT32(a, bits) _rotr(a, bits)
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#else
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#define PR_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
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#define PR_ROTATE_RIGHT32(a, bits) (((a) >> (bits)) | ((a) << (32 - (bits))))
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#endif
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PR_END_EXTERN_C
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#endif /* prbit_h___ */
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