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1 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 : /* This Source Code Form is subject to the terms of the Mozilla Public
3 : * License, v. 2.0. If a copy of the MPL was not distributed with this
4 : * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
5 :
6 : #ifndef prbit_h___
7 : #define prbit_h___
8 :
9 : #include "prtypes.h"
10 : PR_BEGIN_EXTERN_C
11 :
12 : /*
13 : ** Replace compare/jump/add/shift sequence with compiler built-in/intrinsic
14 : ** functions.
15 : */
16 : #if defined(_WIN32) && (_MSC_VER >= 1300) && \
17 : (defined(_M_IX86) || defined(_M_AMD64) || defined(_M_ARM))
18 : # include <intrin.h>
19 : # pragma intrinsic(_BitScanForward,_BitScanReverse)
20 : __forceinline static int __prBitScanForward32(unsigned int val)
21 : {
22 : unsigned long idx;
23 : _BitScanForward(&idx, (unsigned long)val);
24 : return( (int)idx );
25 : }
26 : __forceinline static int __prBitScanReverse32(unsigned int val)
27 : {
28 : unsigned long idx;
29 : _BitScanReverse(&idx, (unsigned long)val);
30 : return( (int)(31-idx) );
31 : }
32 : # define pr_bitscan_ctz32(val) __prBitScanForward32(val)
33 : # define pr_bitscan_clz32(val) __prBitScanReverse32(val)
34 : # define PR_HAVE_BUILTIN_BITSCAN32
35 : #elif ((__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) && \
36 : (defined(__i386__) || defined(__x86_64__) || defined(__arm__))
37 : # define pr_bitscan_ctz32(val) __builtin_ctz(val)
38 : # define pr_bitscan_clz32(val) __builtin_clz(val)
39 : # define PR_HAVE_BUILTIN_BITSCAN32
40 : #endif /* MSVC || GCC */
41 :
42 : /*
43 : ** A prbitmap_t is a long integer that can be used for bitmaps
44 : */
45 : typedef unsigned long prbitmap_t;
46 :
47 : #define PR_TEST_BIT(_map,_bit) \
48 : ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
49 : #define PR_SET_BIT(_map,_bit) \
50 : ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
51 : #define PR_CLEAR_BIT(_map,_bit) \
52 : ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1))))
53 :
54 : /*
55 : ** Compute the log of the least power of 2 greater than or equal to n
56 : */
57 91 : NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i);
58 :
59 : /*
60 : ** Compute the log of the greatest power of 2 less than or equal to n
61 : */
62 0 : NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i);
63 :
64 : /*
65 : ** Macro version of PR_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 : #ifdef PR_HAVE_BUILTIN_BITSCAN32
69 : #define PR_CEILING_LOG2(_log2,_n) \
70 : PR_BEGIN_MACRO \
71 : PRUint32 j_ = (PRUint32)(_n); \
72 : (_log2) = (j_ <= 1 ? 0 : 32 - pr_bitscan_clz32(j_ - 1)); \
73 : PR_END_MACRO
74 : #else
75 : #define PR_CEILING_LOG2(_log2,_n) \
76 : PR_BEGIN_MACRO \
77 : PRUint32 j_ = (PRUint32)(_n); \
78 : (_log2) = 0; \
79 : if ((j_) & ((j_)-1)) \
80 : (_log2) += 1; \
81 : if ((j_) >> 16) \
82 : (_log2) += 16, (j_) >>= 16; \
83 : if ((j_) >> 8) \
84 : (_log2) += 8, (j_) >>= 8; \
85 : if ((j_) >> 4) \
86 : (_log2) += 4, (j_) >>= 4; \
87 : if ((j_) >> 2) \
88 : (_log2) += 2, (j_) >>= 2; \
89 : if ((j_) >> 1) \
90 : (_log2) += 1; \
91 : PR_END_MACRO
92 : #endif /* PR_HAVE_BUILTIN_BITSCAN32 */
93 :
94 : /*
95 : ** Macro version of PR_FloorLog2: Compute the log of the greatest power of
96 : ** 2 less than or equal to _n. The result is returned in _log2.
97 : **
98 : ** This is equivalent to finding the highest set bit in the word.
99 : */
100 : #ifdef PR_HAVE_BUILTIN_BITSCAN32
101 : #define PR_FLOOR_LOG2(_log2,_n) \
102 : PR_BEGIN_MACRO \
103 : PRUint32 j_ = (PRUint32)(_n); \
104 : (_log2) = 31 - pr_bitscan_clz32((j_) | 1); \
105 : PR_END_MACRO
106 : #else
107 : #define PR_FLOOR_LOG2(_log2,_n) \
108 : PR_BEGIN_MACRO \
109 : PRUint32 j_ = (PRUint32)(_n); \
110 : (_log2) = 0; \
111 : if ((j_) >> 16) \
112 : (_log2) += 16, (j_) >>= 16; \
113 : if ((j_) >> 8) \
114 : (_log2) += 8, (j_) >>= 8; \
115 : if ((j_) >> 4) \
116 : (_log2) += 4, (j_) >>= 4; \
117 : if ((j_) >> 2) \
118 : (_log2) += 2, (j_) >>= 2; \
119 : if ((j_) >> 1) \
120 : (_log2) += 1; \
121 : PR_END_MACRO
122 : #endif /* PR_HAVE_BUILTIN_BITSCAN32 */
123 :
124 : /*
125 : ** Macros for rotate left and right. The argument 'a' must be an unsigned
126 : ** 32-bit integer type such as PRUint32.
127 : **
128 : ** There is no rotate operation in the C Language, so the construct
129 : ** (a << 4) | (a >> 28) is frequently used instead. Most compilers convert
130 : ** this to a rotate instruction, but MSVC doesn't without a little help.
131 : ** To get MSVC to generate a rotate instruction, we have to use the _rotl
132 : ** or _rotr intrinsic and use a pragma to make it inline.
133 : **
134 : ** Note: MSVC in VS2005 will do an inline rotate instruction on the above
135 : ** construct.
136 : */
137 :
138 : #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
139 : defined(_M_X64) || defined(_M_ARM))
140 : #include <stdlib.h>
141 : #pragma intrinsic(_rotl, _rotr)
142 : #define PR_ROTATE_LEFT32(a, bits) _rotl(a, bits)
143 : #define PR_ROTATE_RIGHT32(a, bits) _rotr(a, bits)
144 : #else
145 : #define PR_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
146 : #define PR_ROTATE_RIGHT32(a, bits) (((a) >> (bits)) | ((a) << (32 - (bits))))
147 : #endif
148 :
149 : PR_END_EXTERN_C
150 : #endif /* prbit_h___ */
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