зеркало из https://github.com/mozilla/gecko-dev.git
91 строка
2.9 KiB
C
91 строка
2.9 KiB
C
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.0 (the "NPL"); you may not use this file except in
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* compliance with the NPL. You may obtain a copy of the NPL at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the NPL is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
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* for the specific language governing rights and limitations under the
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* NPL.
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*
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* The Initial Developer of this code under the NPL is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All Rights
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* Reserved.
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*/
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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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/*
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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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PR_EXTERN(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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PR_EXTERN(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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#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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/*
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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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#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 /* prbit_h___ */
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