1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/nsprpub/pr/include/prbit.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,151 @@
1.4 +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef prbit_h___
1.10 +#define prbit_h___
1.11 +
1.12 +#include "prtypes.h"
1.13 +PR_BEGIN_EXTERN_C
1.14 +
1.15 +/*
1.16 +** Replace compare/jump/add/shift sequence with compiler built-in/intrinsic
1.17 +** functions.
1.18 +*/
1.19 +#if defined(_WIN32) && (_MSC_VER >= 1300) && \
1.20 + (defined(_M_IX86) || defined(_M_AMD64) || defined(_M_ARM))
1.21 + unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask);
1.22 + unsigned char _BitScanReverse(unsigned long * Index, unsigned long Mask);
1.23 +# pragma intrinsic(_BitScanForward,_BitScanReverse)
1.24 + __forceinline static int __prBitScanForward32(unsigned int val)
1.25 + {
1.26 + unsigned long idx;
1.27 + _BitScanForward(&idx, (unsigned long)val);
1.28 + return( (int)idx );
1.29 + }
1.30 + __forceinline static int __prBitScanReverse32(unsigned int val)
1.31 + {
1.32 + unsigned long idx;
1.33 + _BitScanReverse(&idx, (unsigned long)val);
1.34 + return( (int)(31-idx) );
1.35 + }
1.36 +# define pr_bitscan_ctz32(val) __prBitScanForward32(val)
1.37 +# define pr_bitscan_clz32(val) __prBitScanReverse32(val)
1.38 +# define PR_HAVE_BUILTIN_BITSCAN32
1.39 +#elif ((__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) && \
1.40 + (defined(__i386__) || defined(__x86_64__) || defined(__arm__))
1.41 +# define pr_bitscan_ctz32(val) __builtin_ctz(val)
1.42 +# define pr_bitscan_clz32(val) __builtin_clz(val)
1.43 +# define PR_HAVE_BUILTIN_BITSCAN32
1.44 +#endif /* MSVC || GCC */
1.45 +
1.46 +/*
1.47 +** A prbitmap_t is a long integer that can be used for bitmaps
1.48 +*/
1.49 +typedef unsigned long prbitmap_t;
1.50 +
1.51 +#define PR_TEST_BIT(_map,_bit) \
1.52 + ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
1.53 +#define PR_SET_BIT(_map,_bit) \
1.54 + ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
1.55 +#define PR_CLEAR_BIT(_map,_bit) \
1.56 + ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1))))
1.57 +
1.58 +/*
1.59 +** Compute the log of the least power of 2 greater than or equal to n
1.60 +*/
1.61 +NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i);
1.62 +
1.63 +/*
1.64 +** Compute the log of the greatest power of 2 less than or equal to n
1.65 +*/
1.66 +NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i);
1.67 +
1.68 +/*
1.69 +** Macro version of PR_CeilingLog2: Compute the log of the least power of
1.70 +** 2 greater than or equal to _n. The result is returned in _log2.
1.71 +*/
1.72 +#ifdef PR_HAVE_BUILTIN_BITSCAN32
1.73 +#define PR_CEILING_LOG2(_log2,_n) \
1.74 + PR_BEGIN_MACRO \
1.75 + PRUint32 j_ = (PRUint32)(_n); \
1.76 + (_log2) = (j_ <= 1 ? 0 : 32 - pr_bitscan_clz32(j_ - 1)); \
1.77 + PR_END_MACRO
1.78 +#else
1.79 +#define PR_CEILING_LOG2(_log2,_n) \
1.80 + PR_BEGIN_MACRO \
1.81 + PRUint32 j_ = (PRUint32)(_n); \
1.82 + (_log2) = 0; \
1.83 + if ((j_) & ((j_)-1)) \
1.84 + (_log2) += 1; \
1.85 + if ((j_) >> 16) \
1.86 + (_log2) += 16, (j_) >>= 16; \
1.87 + if ((j_) >> 8) \
1.88 + (_log2) += 8, (j_) >>= 8; \
1.89 + if ((j_) >> 4) \
1.90 + (_log2) += 4, (j_) >>= 4; \
1.91 + if ((j_) >> 2) \
1.92 + (_log2) += 2, (j_) >>= 2; \
1.93 + if ((j_) >> 1) \
1.94 + (_log2) += 1; \
1.95 + PR_END_MACRO
1.96 +#endif /* PR_HAVE_BUILTIN_BITSCAN32 */
1.97 +
1.98 +/*
1.99 +** Macro version of PR_FloorLog2: Compute the log of the greatest power of
1.100 +** 2 less than or equal to _n. The result is returned in _log2.
1.101 +**
1.102 +** This is equivalent to finding the highest set bit in the word.
1.103 +*/
1.104 +#ifdef PR_HAVE_BUILTIN_BITSCAN32
1.105 +#define PR_FLOOR_LOG2(_log2,_n) \
1.106 + PR_BEGIN_MACRO \
1.107 + PRUint32 j_ = (PRUint32)(_n); \
1.108 + (_log2) = 31 - pr_bitscan_clz32((j_) | 1); \
1.109 + PR_END_MACRO
1.110 +#else
1.111 +#define PR_FLOOR_LOG2(_log2,_n) \
1.112 + PR_BEGIN_MACRO \
1.113 + PRUint32 j_ = (PRUint32)(_n); \
1.114 + (_log2) = 0; \
1.115 + if ((j_) >> 16) \
1.116 + (_log2) += 16, (j_) >>= 16; \
1.117 + if ((j_) >> 8) \
1.118 + (_log2) += 8, (j_) >>= 8; \
1.119 + if ((j_) >> 4) \
1.120 + (_log2) += 4, (j_) >>= 4; \
1.121 + if ((j_) >> 2) \
1.122 + (_log2) += 2, (j_) >>= 2; \
1.123 + if ((j_) >> 1) \
1.124 + (_log2) += 1; \
1.125 + PR_END_MACRO
1.126 +#endif /* PR_HAVE_BUILTIN_BITSCAN32 */
1.127 +
1.128 +/*
1.129 +** Macros for rotate left and right. The argument 'a' must be an unsigned
1.130 +** 32-bit integer type such as PRUint32.
1.131 +**
1.132 +** There is no rotate operation in the C Language, so the construct
1.133 +** (a << 4) | (a >> 28) is frequently used instead. Most compilers convert
1.134 +** this to a rotate instruction, but MSVC doesn't without a little help.
1.135 +** To get MSVC to generate a rotate instruction, we have to use the _rotl
1.136 +** or _rotr intrinsic and use a pragma to make it inline.
1.137 +**
1.138 +** Note: MSVC in VS2005 will do an inline rotate instruction on the above
1.139 +** construct.
1.140 +*/
1.141 +
1.142 +#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
1.143 + defined(_M_X64) || defined(_M_ARM))
1.144 +#include <stdlib.h>
1.145 +#pragma intrinsic(_rotl, _rotr)
1.146 +#define PR_ROTATE_LEFT32(a, bits) _rotl(a, bits)
1.147 +#define PR_ROTATE_RIGHT32(a, bits) _rotr(a, bits)
1.148 +#else
1.149 +#define PR_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
1.150 +#define PR_ROTATE_RIGHT32(a, bits) (((a) >> (bits)) | ((a) << (32 - (bits))))
1.151 +#endif
1.152 +
1.153 +PR_END_EXTERN_C
1.154 +#endif /* prbit_h___ */
