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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 Netscape 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/NPL/
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 Mozilla Communicator client code, released
14: * March 31, 1998.
15: *
16: * The Initial Developer of the Original Code is Netscape
17: * Communications Corporation. Portions created by Netscape are
18: * Copyright (C) 1998 Netscape Communications Corporation. All
19: * Rights Reserved.
20: *
21: * Contributor(s):
22: *
23: * Alternatively, the contents of this file may be used under the
24: * terms of the GNU Public License (the "GPL"), in which case the
25: * provisions of the GPL are applicable instead of those above.
26: * If you wish to allow use of your version of this file only
27: * under the terms of the GPL and not to allow others to use your
28: * version of this file under the NPL, indicate your decision by
29: * deleting the provisions above and replace them with the notice
30: * and other provisions required by the GPL. If you do not delete
31: * the provisions above, a recipient may use your version of this
32: * file under either the NPL or the GPL.
33: */
34:
35: #ifndef jsbit_h___
36: #define jsbit_h___
37:
38: #include "jstypes.h"
39: JS_BEGIN_EXTERN_C
40:
41: /*
42: ** A jsbitmap_t is a long integer that can be used for bitmaps
43: */
44: typedef JSUword jsbitmap_t; /* NSPR name, a la Unix system types */
45: typedef jsbitmap_t jsbitmap; /* JS-style scalar typedef name */
46:
47: #define JS_TEST_BIT(_map,_bit) \
48: ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] & (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
49: #define JS_SET_BIT(_map,_bit) \
50: ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |= (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
51: #define JS_CLEAR_BIT(_map,_bit) \
52: ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &= ~(1L << ((_bit) & (JS_BITS_PER_WORD-1))))
53:
54: /*
55: ** Compute the log of the least power of 2 greater than or equal to n
56: */
57: extern JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 i);
58:
59: /*
60: ** Compute the log of the greatest power of 2 less than or equal to n
61: */
62: extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i);
63:
64: /*
65: ** Macro version of JS_CeilingLog2: Compute the log of the least power of
66: ** 2 greater than or equal to _n. The result is returned in _log2.
67: */
68: #define JS_CEILING_LOG2(_log2,_n) \
69: JS_BEGIN_MACRO \
70: JSUint32 j_ = (JSUint32)(_n); \
71: (_log2) = 0; \
72: if ((j_) & ((j_)-1)) \
73: (_log2) += 1; \
74: if ((j_) >> 16) \
75: (_log2) += 16, (j_) >>= 16; \
76: if ((j_) >> 8) \
77: (_log2) += 8, (j_) >>= 8; \
78: if ((j_) >> 4) \
79: (_log2) += 4, (j_) >>= 4; \
80: if ((j_) >> 2) \
81: (_log2) += 2, (j_) >>= 2; \
82: if ((j_) >> 1) \
83: (_log2) += 1; \
84: JS_END_MACRO
85:
86: /*
87: ** Macro version of JS_FloorLog2: Compute the log of the greatest power of
88: ** 2 less than or equal to _n. The result is returned in _log2.
89: **
90: ** This is equivalent to finding the highest set bit in the word.
91: */
92: #define JS_FLOOR_LOG2(_log2,_n) \
93: JS_BEGIN_MACRO \
94: JSUint32 j_ = (JSUint32)(_n); \
95: (_log2) = 0; \
96: if ((j_) >> 16) \
97: (_log2) += 16, (j_) >>= 16; \
98: if ((j_) >> 8) \
99: (_log2) += 8, (j_) >>= 8; \
100: if ((j_) >> 4) \
101: (_log2) += 4, (j_) >>= 4; \
102: if ((j_) >> 2) \
103: (_log2) += 2, (j_) >>= 2; \
104: if ((j_) >> 1) \
105: (_log2) += 1; \
106: JS_END_MACRO
107:
108: JS_END_EXTERN_C
109: #endif /* jsbit_h___ */
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