prbit.h (5274B)
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_X64) || defined(_M_ARM) || \ 18 defined(_M_ARM64)) 19 # include <intrin.h> 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 defined(__aarch64__)) 39 # define pr_bitscan_ctz32(val) __builtin_ctz(val) 40 # define pr_bitscan_clz32(val) __builtin_clz(val) 41 # define PR_HAVE_BUILTIN_BITSCAN32 42 #endif /* MSVC || GCC */ 43 44 /* 45 ** A prbitmap_t is a long integer that can be used for bitmaps 46 */ 47 typedef unsigned long prbitmap_t; 48 49 #define PR_TEST_BIT(_map,_bit) \ 50 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1)))) 51 #define PR_SET_BIT(_map,_bit) \ 52 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1)))) 53 #define PR_CLEAR_BIT(_map,_bit) \ 54 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1)))) 55 56 /* 57 ** Compute the log of the least power of 2 greater than or equal to n 58 */ 59 NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i); 60 61 /* 62 ** Compute the log of the greatest power of 2 less than or equal to n 63 */ 64 NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i); 65 66 /* 67 ** Macro version of PR_CeilingLog2: Compute the log of the least power of 68 ** 2 greater than or equal to _n. The result is returned in _log2. 69 */ 70 #ifdef PR_HAVE_BUILTIN_BITSCAN32 71 #define PR_CEILING_LOG2(_log2,_n) \ 72 PR_BEGIN_MACRO \ 73 PRUint32 j_ = (PRUint32)(_n); \ 74 (_log2) = (j_ <= 1 ? 0 : 32 - pr_bitscan_clz32(j_ - 1)); \ 75 PR_END_MACRO 76 #else 77 #define PR_CEILING_LOG2(_log2,_n) \ 78 PR_BEGIN_MACRO \ 79 PRUint32 j_ = (PRUint32)(_n); \ 80 (_log2) = 0; \ 81 if ((j_) & ((j_)-1)) \ 82 (_log2) += 1; \ 83 if ((j_) >> 16) \ 84 (_log2) += 16, (j_) >>= 16; \ 85 if ((j_) >> 8) \ 86 (_log2) += 8, (j_) >>= 8; \ 87 if ((j_) >> 4) \ 88 (_log2) += 4, (j_) >>= 4; \ 89 if ((j_) >> 2) \ 90 (_log2) += 2, (j_) >>= 2; \ 91 if ((j_) >> 1) \ 92 (_log2) += 1; \ 93 PR_END_MACRO 94 #endif /* PR_HAVE_BUILTIN_BITSCAN32 */ 95 96 /* 97 ** Macro version of PR_FloorLog2: Compute the log of the greatest power of 98 ** 2 less than or equal to _n. The result is returned in _log2. 99 ** 100 ** This is equivalent to finding the highest set bit in the word. 101 */ 102 #ifdef PR_HAVE_BUILTIN_BITSCAN32 103 #define PR_FLOOR_LOG2(_log2,_n) \ 104 PR_BEGIN_MACRO \ 105 PRUint32 j_ = (PRUint32)(_n); \ 106 (_log2) = 31 - pr_bitscan_clz32((j_) | 1); \ 107 PR_END_MACRO 108 #else 109 #define PR_FLOOR_LOG2(_log2,_n) \ 110 PR_BEGIN_MACRO \ 111 PRUint32 j_ = (PRUint32)(_n); \ 112 (_log2) = 0; \ 113 if ((j_) >> 16) \ 114 (_log2) += 16, (j_) >>= 16; \ 115 if ((j_) >> 8) \ 116 (_log2) += 8, (j_) >>= 8; \ 117 if ((j_) >> 4) \ 118 (_log2) += 4, (j_) >>= 4; \ 119 if ((j_) >> 2) \ 120 (_log2) += 2, (j_) >>= 2; \ 121 if ((j_) >> 1) \ 122 (_log2) += 1; \ 123 PR_END_MACRO 124 #endif /* PR_HAVE_BUILTIN_BITSCAN32 */ 125 126 /* 127 ** Macros for rotate left and right. The argument 'a' must be an unsigned 128 ** 32-bit integer type such as PRUint32. 129 ** 130 ** There is no rotate operation in the C Language, so the construct 131 ** (a << 4) | (a >> 28) is frequently used instead. Most compilers convert 132 ** this to a rotate instruction, but MSVC doesn't without a little help. 133 ** To get MSVC to generate a rotate instruction, we have to use the _rotl 134 ** or _rotr intrinsic and use a pragma to make it inline. 135 ** 136 ** Note: MSVC in VS2005 will do an inline rotate instruction on the above 137 ** construct. 138 */ 139 140 #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \ 141 defined(_M_X64) || defined(_M_ARM) || defined(_M_ARM64)) 142 #include <stdlib.h> 143 #pragma intrinsic(_rotl, _rotr) 144 #define PR_ROTATE_LEFT32(a, bits) _rotl(a, bits) 145 #define PR_ROTATE_RIGHT32(a, bits) _rotr(a, bits) 146 #else 147 #define PR_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits)))) 148 #define PR_ROTATE_RIGHT32(a, bits) (((a) >> (bits)) | ((a) << (32 - (bits)))) 149 #endif 150 151 PR_END_EXTERN_C 152 #endif /* prbit_h___ */