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Diffstat (limited to 'nsprpub/pr/include/prbit.h')
| -rw-r--r-- | nsprpub/pr/include/prbit.h | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/nsprpub/pr/include/prbit.h b/nsprpub/pr/include/prbit.h new file mode 100644 index 000000000..0434fc683 --- /dev/null +++ b/nsprpub/pr/include/prbit.h @@ -0,0 +1,150 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef prbit_h___ +#define prbit_h___ + +#include "prtypes.h" +PR_BEGIN_EXTERN_C + +/* +** Replace compare/jump/add/shift sequence with compiler built-in/intrinsic +** functions. +*/ +#if defined(_WIN32) && (_MSC_VER >= 1300) && \ + (defined(_M_IX86) || defined(_M_AMD64) || defined(_M_ARM)) +# include <intrin.h> +# pragma intrinsic(_BitScanForward,_BitScanReverse) + __forceinline static int __prBitScanForward32(unsigned int val) + { + unsigned long idx; + _BitScanForward(&idx, (unsigned long)val); + return( (int)idx ); + } + __forceinline static int __prBitScanReverse32(unsigned int val) + { + unsigned long idx; + _BitScanReverse(&idx, (unsigned long)val); + return( (int)(31-idx) ); + } +# define pr_bitscan_ctz32(val) __prBitScanForward32(val) +# define pr_bitscan_clz32(val) __prBitScanReverse32(val) +# define PR_HAVE_BUILTIN_BITSCAN32 +#elif ((__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) && \ + (defined(__i386__) || defined(__x86_64__) || defined(__arm__)) +# define pr_bitscan_ctz32(val) __builtin_ctz(val) +# define pr_bitscan_clz32(val) __builtin_clz(val) +# define PR_HAVE_BUILTIN_BITSCAN32 +#endif /* MSVC || GCC */ + +/* +** A prbitmap_t is a long integer that can be used for bitmaps +*/ +typedef unsigned long prbitmap_t; + +#define PR_TEST_BIT(_map,_bit) \ + ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1)))) +#define PR_SET_BIT(_map,_bit) \ + ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1)))) +#define PR_CLEAR_BIT(_map,_bit) \ + ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1)))) + +/* +** Compute the log of the least power of 2 greater than or equal to n +*/ +NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i); + +/* +** Compute the log of the greatest power of 2 less than or equal to n +*/ +NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i); + +/* +** Macro version of PR_CeilingLog2: Compute the log of the least power of +** 2 greater than or equal to _n. The result is returned in _log2. +*/ +#ifdef PR_HAVE_BUILTIN_BITSCAN32 +#define PR_CEILING_LOG2(_log2,_n) \ + PR_BEGIN_MACRO \ + PRUint32 j_ = (PRUint32)(_n); \ + (_log2) = (j_ <= 1 ? 0 : 32 - pr_bitscan_clz32(j_ - 1)); \ + PR_END_MACRO +#else +#define PR_CEILING_LOG2(_log2,_n) \ + PR_BEGIN_MACRO \ + PRUint32 j_ = (PRUint32)(_n); \ + (_log2) = 0; \ + if ((j_) & ((j_)-1)) \ + (_log2) += 1; \ + if ((j_) >> 16) \ + (_log2) += 16, (j_) >>= 16; \ + if ((j_) >> 8) \ + (_log2) += 8, (j_) >>= 8; \ + if ((j_) >> 4) \ + (_log2) += 4, (j_) >>= 4; \ + if ((j_) >> 2) \ + (_log2) += 2, (j_) >>= 2; \ + if ((j_) >> 1) \ + (_log2) += 1; \ + PR_END_MACRO +#endif /* PR_HAVE_BUILTIN_BITSCAN32 */ + +/* +** Macro version of PR_FloorLog2: Compute the log of the greatest power of +** 2 less than or equal to _n. The result is returned in _log2. +** +** This is equivalent to finding the highest set bit in the word. +*/ +#ifdef PR_HAVE_BUILTIN_BITSCAN32 +#define PR_FLOOR_LOG2(_log2,_n) \ + PR_BEGIN_MACRO \ + PRUint32 j_ = (PRUint32)(_n); \ + (_log2) = 31 - pr_bitscan_clz32((j_) | 1); \ + PR_END_MACRO +#else +#define PR_FLOOR_LOG2(_log2,_n) \ + PR_BEGIN_MACRO \ + PRUint32 j_ = (PRUint32)(_n); \ + (_log2) = 0; \ + if ((j_) >> 16) \ + (_log2) += 16, (j_) >>= 16; \ + if ((j_) >> 8) \ + (_log2) += 8, (j_) >>= 8; \ + if ((j_) >> 4) \ + (_log2) += 4, (j_) >>= 4; \ + if ((j_) >> 2) \ + (_log2) += 2, (j_) >>= 2; \ + if ((j_) >> 1) \ + (_log2) += 1; \ + PR_END_MACRO +#endif /* PR_HAVE_BUILTIN_BITSCAN32 */ + +/* +** Macros for rotate left and right. The argument 'a' must be an unsigned +** 32-bit integer type such as PRUint32. +** +** There is no rotate operation in the C Language, so the construct +** (a << 4) | (a >> 28) is frequently used instead. Most compilers convert +** this to a rotate instruction, but MSVC doesn't without a little help. +** To get MSVC to generate a rotate instruction, we have to use the _rotl +** or _rotr intrinsic and use a pragma to make it inline. +** +** Note: MSVC in VS2005 will do an inline rotate instruction on the above +** construct. +*/ + +#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \ + defined(_M_X64) || defined(_M_ARM)) +#include <stdlib.h> +#pragma intrinsic(_rotl, _rotr) +#define PR_ROTATE_LEFT32(a, bits) _rotl(a, bits) +#define PR_ROTATE_RIGHT32(a, bits) _rotr(a, bits) +#else +#define PR_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits)))) +#define PR_ROTATE_RIGHT32(a, bits) (((a) >> (bits)) | ((a) << (32 - (bits)))) +#endif + +PR_END_EXTERN_C +#endif /* prbit_h___ */ |