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1.1 root 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"
39: PR_BEGIN_EXTERN_C
40:
41: /*
42: ** A prbitmap_t is a long integer that can be used for bitmaps
43: */
44: typedef 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: */
56: NSPR_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: */
61: NSPR_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:
107: PR_END_EXTERN_C
108: #endif /* prbit_h___ */
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