/gecko_api/include/prbit.h

  1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  2/* ***** BEGIN LICENSE BLOCK *****
  3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  4 *
  5 * The contents of this file are subject to the Mozilla Public License Version
  6 * 1.1 (the "License"); you may not use this file except in compliance with
  7 * the License. You may obtain a copy of the License at
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 10 * Software distributed under the License is distributed on an "AS IS" basis,
 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 12 * for the specific language governing rights and limitations under the
 13 * License.
 14 *
 15 * The Original Code is the Netscape Portable Runtime (NSPR).
 16 *
 17 * The Initial Developer of the Original Code is
 18 * Netscape Communications Corporation.
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 20 * the Initial Developer. All Rights Reserved.
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 22 * Contributor(s):
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 36 * ***** END LICENSE BLOCK ***** */
 37
 38#ifndef prbit_h___
 39#define prbit_h___
 40
 41#include "prtypes.h"
 42PR_BEGIN_EXTERN_C
 43
 44/*
 45** A prbitmap_t is a long integer that can be used for bitmaps
 46*/
 47typedef unsigned long prbitmap_t;
 48
 49#define PR_TEST_BIT(_map,_bit) \
 50    ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
 51#define PR_SET_BIT(_map,_bit) \
 52    ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
 53#define PR_CLEAR_BIT(_map,_bit) \
 54    ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1))))
 55
 56/*
 57** Compute the log of the least power of 2 greater than or equal to n
 58*/
 59NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i); 
 60
 61/*
 62** Compute the log of the greatest power of 2 less than or equal to n
 63*/
 64NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i); 
 65
 66/*
 67** Macro version of PR_CeilingLog2: Compute the log of the least power of
 68** 2 greater than or equal to _n. The result is returned in _log2.
 69*/
 70#define PR_CEILING_LOG2(_log2,_n)   \
 71  PR_BEGIN_MACRO                    \
 72    PRUint32 j_ = (PRUint32)(_n); 	\
 73    (_log2) = 0;                    \
 74    if ((j_) & ((j_)-1))            \
 75	(_log2) += 1;               \
 76    if ((j_) >> 16)                 \
 77	(_log2) += 16, (j_) >>= 16; \
 78    if ((j_) >> 8)                  \
 79	(_log2) += 8, (j_) >>= 8;   \
 80    if ((j_) >> 4)                  \
 81	(_log2) += 4, (j_) >>= 4;   \
 82    if ((j_) >> 2)                  \
 83	(_log2) += 2, (j_) >>= 2;   \
 84    if ((j_) >> 1)                  \
 85	(_log2) += 1;               \
 86  PR_END_MACRO
 87
 88/*
 89** Macro version of PR_FloorLog2: Compute the log of the greatest power of
 90** 2 less than or equal to _n. The result is returned in _log2.
 91**
 92** This is equivalent to finding the highest set bit in the word.
 93*/
 94#define PR_FLOOR_LOG2(_log2,_n)   \
 95  PR_BEGIN_MACRO                    \
 96    PRUint32 j_ = (PRUint32)(_n); 	\
 97    (_log2) = 0;                    \
 98    if ((j_) >> 16)                 \
 99	(_log2) += 16, (j_) >>= 16; \
100    if ((j_) >> 8)                  \
101	(_log2) += 8, (j_) >>= 8;   \
102    if ((j_) >> 4)                  \
103	(_log2) += 4, (j_) >>= 4;   \
104    if ((j_) >> 2)                  \
105	(_log2) += 2, (j_) >>= 2;   \
106    if ((j_) >> 1)                  \
107	(_log2) += 1;               \
108  PR_END_MACRO
109
110/*
111** Macros for rotate left and right. The argument 'a' must be an unsigned
112** 32-bit integer type such as PRUint32.
113**
114** There is no rotate operation in the C Language, so the construct
115** (a << 4) | (a >> 28) is frequently used instead. Most compilers convert
116** this to a rotate instruction, but MSVC doesn't without a little help.
117** To get MSVC to generate a rotate instruction, we have to use the _rotl
118** or _rotr intrinsic and use a pragma to make it inline.
119**
120** Note: MSVC in VS2005 will do an inline rotate instruction on the above
121** construct.
122*/
123
124#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
125    defined(_M_X64))
126#include <stdlib.h>
127#pragma intrinsic(_rotl, _rotr)
128#define PR_ROTATE_LEFT32(a, bits) _rotl(a, bits)
129#define PR_ROTATE_RIGHT32(a, bits) _rotr(a, bits)
130#else
131#define PR_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
132#define PR_ROTATE_RIGHT32(a, bits) (((a) >> (bits)) | ((a) << (32 - (bits))))
133#endif
134
135PR_END_EXTERN_C
136#endif /* prbit_h___ */