nsprpub/pr/include/prbit.h@6474c204b198
nsprpub/pr/include/prbit.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
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/. */
6 #ifndef prbit_h___
7 #define prbit_h___
9 #include "prtypes.h"
10 PR_BEGIN_EXTERN_C
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 unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask);
19 unsigned char _BitScanReverse(unsigned long * Index, unsigned long Mask);
20 # pragma intrinsic(_BitScanForward,_BitScanReverse)
21 __forceinline static int __prBitScanForward32(unsigned int val)
22 {
23 unsigned long idx;
24 _BitScanForward(&idx, (unsigned long)val);
25 return( (int)idx );
26 }
27 __forceinline static int __prBitScanReverse32(unsigned int val)
28 {
29 unsigned long idx;
30 _BitScanReverse(&idx, (unsigned long)val);
31 return( (int)(31-idx) );
32 }
33 # define pr_bitscan_ctz32(val) __prBitScanForward32(val)
34 # define pr_bitscan_clz32(val) __prBitScanReverse32(val)
35 # define PR_HAVE_BUILTIN_BITSCAN32
36 #elif ((__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) && \
37 (defined(__i386__) || defined(__x86_64__) || defined(__arm__))
38 # define pr_bitscan_ctz32(val) __builtin_ctz(val)
39 # define pr_bitscan_clz32(val) __builtin_clz(val)
40 # define PR_HAVE_BUILTIN_BITSCAN32
41 #endif /* MSVC || GCC */
43 /*
44 ** A prbitmap_t is a long integer that can be used for bitmaps
45 */
46 typedef unsigned long prbitmap_t;
48 #define PR_TEST_BIT(_map,_bit) \
49 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
50 #define PR_SET_BIT(_map,_bit) \
51 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
52 #define PR_CLEAR_BIT(_map,_bit) \
53 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1))))
55 /*
56 ** Compute the log of the least power of 2 greater than or equal to n
57 */
58 NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i);
60 /*
61 ** Compute the log of the greatest power of 2 less than or equal to n
62 */
63 NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i);
65 /*
66 ** Macro version of PR_CeilingLog2: Compute the log of the least power of
67 ** 2 greater than or equal to _n. The result is returned in _log2.
68 */
69 #ifdef PR_HAVE_BUILTIN_BITSCAN32
70 #define PR_CEILING_LOG2(_log2,_n) \
71 PR_BEGIN_MACRO \
72 PRUint32 j_ = (PRUint32)(_n); \
73 (_log2) = (j_ <= 1 ? 0 : 32 - pr_bitscan_clz32(j_ - 1)); \
74 PR_END_MACRO
75 #else
76 #define PR_CEILING_LOG2(_log2,_n) \
77 PR_BEGIN_MACRO \
78 PRUint32 j_ = (PRUint32)(_n); \
79 (_log2) = 0; \
80 if ((j_) & ((j_)-1)) \
81 (_log2) += 1; \
82 if ((j_) >> 16) \
83 (_log2) += 16, (j_) >>= 16; \
84 if ((j_) >> 8) \
85 (_log2) += 8, (j_) >>= 8; \
86 if ((j_) >> 4) \
87 (_log2) += 4, (j_) >>= 4; \
88 if ((j_) >> 2) \
89 (_log2) += 2, (j_) >>= 2; \
90 if ((j_) >> 1) \
91 (_log2) += 1; \
92 PR_END_MACRO
93 #endif /* PR_HAVE_BUILTIN_BITSCAN32 */
95 /*
96 ** Macro version of PR_FloorLog2: Compute the log of the greatest power of
97 ** 2 less than or equal to _n. The result is returned in _log2.
98 **
99 ** This is equivalent to finding the highest set bit in the word.
100 */
101 #ifdef PR_HAVE_BUILTIN_BITSCAN32
102 #define PR_FLOOR_LOG2(_log2,_n) \
103 PR_BEGIN_MACRO \
104 PRUint32 j_ = (PRUint32)(_n); \
105 (_log2) = 31 - pr_bitscan_clz32((j_) | 1); \
106 PR_END_MACRO
107 #else
108 #define PR_FLOOR_LOG2(_log2,_n) \
109 PR_BEGIN_MACRO \
110 PRUint32 j_ = (PRUint32)(_n); \
111 (_log2) = 0; \
112 if ((j_) >> 16) \
113 (_log2) += 16, (j_) >>= 16; \
114 if ((j_) >> 8) \
115 (_log2) += 8, (j_) >>= 8; \
116 if ((j_) >> 4) \
117 (_log2) += 4, (j_) >>= 4; \
118 if ((j_) >> 2) \
119 (_log2) += 2, (j_) >>= 2; \
120 if ((j_) >> 1) \
121 (_log2) += 1; \
122 PR_END_MACRO
123 #endif /* PR_HAVE_BUILTIN_BITSCAN32 */
125 /*
126 ** Macros for rotate left and right. The argument 'a' must be an unsigned
127 ** 32-bit integer type such as PRUint32.
128 **
129 ** There is no rotate operation in the C Language, so the construct
130 ** (a << 4) | (a >> 28) is frequently used instead. Most compilers convert
131 ** this to a rotate instruction, but MSVC doesn't without a little help.
132 ** To get MSVC to generate a rotate instruction, we have to use the _rotl
133 ** or _rotr intrinsic and use a pragma to make it inline.
134 **
135 ** Note: MSVC in VS2005 will do an inline rotate instruction on the above
136 ** construct.
137 */
139 #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
140 defined(_M_X64) || defined(_M_ARM))
141 #include <stdlib.h>
142 #pragma intrinsic(_rotl, _rotr)
143 #define PR_ROTATE_LEFT32(a, bits) _rotl(a, bits)
144 #define PR_ROTATE_RIGHT32(a, bits) _rotr(a, bits)
145 #else
146 #define PR_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
147 #define PR_ROTATE_RIGHT32(a, bits) (((a) >> (bits)) | ((a) << (32 - (bits))))
148 #endif
150 PR_END_EXTERN_C
151 #endif /* prbit_h___ */
