1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/*
3 * The contents of this file are subject to the Mozilla Public
4 * License Version 1.1 (the "License"); you may not use this file
5 * except in compliance with the License. You may obtain a copy of
6 * the License at http://www.mozilla.org/MPL/
7 *
8 * Software distributed under the License is distributed on an "AS
9 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
10 * implied. See the License for the specific language governing
11 * rights and limitations under the License.
12 *
13 * The Original Code is the Netscape Portable Runtime (NSPR).
14 *
15 * The Initial Developer of the Original Code is Netscape
16 * Communications Corporation.  Portions created by Netscape are
17 * Copyright (C) 1998-2000 Netscape Communications Corporation.  All
18 * Rights Reserved.
19 *
20 * Contributor(s):
21 *
22 * Alternatively, the contents of this file may be used under the
23 * terms of the GNU General Public License Version 2 or later (the
24 * "GPL"), in which case the provisions of the GPL are applicable
25 * instead of those above.  If you wish to allow use of your
26 * version of this file only under the terms of the GPL and not to
27 * allow others to use your version of this file under the MPL,
28 * indicate your decision by deleting the provisions above and
29 * replace them with the notice and other provisions required by
30 * the GPL.  If you do not delete the provisions above, a recipient
31 * may use your version of this file under either the MPL or the
32 * GPL.
33 */
34
35#ifndef prbit_h___
36#define prbit_h___
37
38#include "prtypes.h"
39PR_BEGIN_EXTERN_C
40
41/*
42** A prbitmap_t is a long integer that can be used for bitmaps
43*/
44typedef unsigned long prbitmap_t;
45
46#define PR_TEST_BIT(_map,_bit) \
47    ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
48#define PR_SET_BIT(_map,_bit) \
49    ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
50#define PR_CLEAR_BIT(_map,_bit) \
51    ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1))))
52
53/*
54** Compute the log of the least power of 2 greater than or equal to n
55*/
56NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i);
57
58/*
59** Compute the log of the greatest power of 2 less than or equal to n
60*/
61NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i);
62
63/*
64** Macro version of PR_CeilingLog2: Compute the log of the least power of
65** 2 greater than or equal to _n. The result is returned in _log2.
66*/
67#define PR_CEILING_LOG2(_log2,_n)   \
68  PR_BEGIN_MACRO                    \
69    PRUint32 j_ = (PRUint32)(_n); 	\
70    (_log2) = 0;                    \
71    if ((j_) & ((j_)-1))            \
72	(_log2) += 1;               \
73    if ((j_) >> 16)                 \
74	(_log2) += 16, (j_) >>= 16; \
75    if ((j_) >> 8)                  \
76	(_log2) += 8, (j_) >>= 8;   \
77    if ((j_) >> 4)                  \
78	(_log2) += 4, (j_) >>= 4;   \
79    if ((j_) >> 2)                  \
80	(_log2) += 2, (j_) >>= 2;   \
81    if ((j_) >> 1)                  \
82	(_log2) += 1;               \
83  PR_END_MACRO
84
85/*
86** Macro version of PR_FloorLog2: Compute the log of the greatest power of
87** 2 less than or equal to _n. The result is returned in _log2.
88**
89** This is equivalent to finding the highest set bit in the word.
90*/
91#define PR_FLOOR_LOG2(_log2,_n)   \
92  PR_BEGIN_MACRO                    \
93    PRUint32 j_ = (PRUint32)(_n); 	\
94    (_log2) = 0;                    \
95    if ((j_) >> 16)                 \
96	(_log2) += 16, (j_) >>= 16; \
97    if ((j_) >> 8)                  \
98	(_log2) += 8, (j_) >>= 8;   \
99    if ((j_) >> 4)                  \
100	(_log2) += 4, (j_) >>= 4;   \
101    if ((j_) >> 2)                  \
102	(_log2) += 2, (j_) >>= 2;   \
103    if ((j_) >> 1)                  \
104	(_log2) += 1;               \
105  PR_END_MACRO
106
107PR_END_EXTERN_C
108#endif /* prbit_h___ */
109