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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
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/* ***** BEGIN LICENSE BLOCK ***** |
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1 |
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* |
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* The contents of this file are subject to the Mozilla Public License Version |
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* 1.1 (the "License"); you may not use this file except in compliance with |
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* the License. You may obtain a copy of the License at |
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* http://www.mozilla.org/MPL/ |
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* |
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* Software distributed under the License is distributed on an "AS IS" basis, |
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License |
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* for the specific language governing rights and limitations under the |
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* License. |
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* |
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* The Original Code is Mozilla Communicator client code, released |
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* March 31, 1998. |
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* |
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* The Initial Developer of the Original Code is |
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* Netscape Communications Corporation. |
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* Portions created by the Initial Developer are Copyright (C) 1998 |
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* the Initial Developer. All Rights Reserved. |
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* |
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* Contributor(s): |
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* |
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* Alternatively, the contents of this file may be used under the terms of |
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* either of the GNU General Public License Version 2 or later (the "GPL"), |
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), |
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* in which case the provisions of the GPL or the LGPL are applicable instead |
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* of those above. If you wish to allow use of your version of this file only |
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* under the terms of either the GPL or the LGPL, and not to allow others to |
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* use your version of this file under the terms of the MPL, indicate your |
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* decision by deleting the provisions above and replace them with the notice |
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* and other provisions required by the GPL or the LGPL. If you do not delete |
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* the provisions above, a recipient may use your version of this file under |
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* the terms of any one of the MPL, the GPL or the LGPL. |
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* |
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* ***** END LICENSE BLOCK ***** */ |
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#ifndef jsbit_h___ |
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#define jsbit_h___ |
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#include "jstypes.h" |
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#include "jsutil.h" |
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JS_BEGIN_EXTERN_C |
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/* |
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** A jsbitmap_t is a long integer that can be used for bitmaps |
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*/ |
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typedef JSUword jsbitmap_t; /* NSPR name, a la Unix system types */ |
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typedef jsbitmap_t jsbitmap; /* JS-style scalar typedef name */ |
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#define JS_BITMAP_SIZE(bits) (JS_HOWMANY(bits, JS_BITS_PER_WORD) * \ |
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sizeof(jsbitmap)) |
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#define JS_TEST_BIT(_map,_bit) ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] & \ |
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((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1)))) |
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#define JS_SET_BIT(_map,_bit) ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |= \ |
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((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1)))) |
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#define JS_CLEAR_BIT(_map,_bit) ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &= \ |
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~((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1)))) |
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/* |
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** Compute the log of the least power of 2 greater than or equal to n |
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*/ |
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extern JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 i); |
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/* |
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** Compute the log of the greatest power of 2 less than or equal to n |
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*/ |
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extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i); |
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/* |
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* Replace bit-scanning code sequences with CPU-specific instructions to |
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* speedup calculations of ceiling/floor log2. |
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* |
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* With GCC 3.4 or later we can use __builtin_clz for that, see bug 327129. |
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* |
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* SWS: Added MSVC intrinsic bitscan support. See bugs 349364 and 356856. |
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*/ |
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#if defined(_WIN32) && (_MSC_VER >= 1300) && defined(_M_IX86) |
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unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask); |
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unsigned char _BitScanReverse(unsigned long * Index, unsigned long Mask); |
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# pragma intrinsic(_BitScanForward,_BitScanReverse) |
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__forceinline static int |
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__BitScanForward32(unsigned int val) |
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{ |
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unsigned long idx; |
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_BitScanForward(&idx, (unsigned long)val); |
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return (int)idx; |
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} |
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__forceinline static int |
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__BitScanReverse32(unsigned int val) |
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{ |
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unsigned long idx; |
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_BitScanReverse(&idx, (unsigned long)val); |
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return (int)(31-idx); |
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} |
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# define js_bitscan_ctz32(val) __BitScanForward32(val) |
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# define js_bitscan_clz32(val) __BitScanReverse32(val) |
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# define JS_HAS_BUILTIN_BITSCAN32 |
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#elif (__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) |
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# define js_bitscan_ctz32(val) __builtin_ctz(val) |
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# define js_bitscan_clz32(val) __builtin_clz(val) |
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# define JS_HAS_BUILTIN_BITSCAN32 |
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# if (JS_BYTES_PER_WORD == 8) |
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# define js_bitscan_ctz64(val) __builtin_ctzll(val) |
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# define js_bitscan_clz64(val) __builtin_clzll(val) |
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# define JS_HAS_BUILTIN_BITSCAN64 |
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# endif |
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#endif |
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/* |
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** Macro version of JS_CeilingLog2: Compute the log of the least power of |
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** 2 greater than or equal to _n. The result is returned in _log2. |
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*/ |
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#ifdef JS_HAS_BUILTIN_BITSCAN32 |
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/* |
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* Use intrinsic function or count-leading-zeros to calculate ceil(log2(_n)). |
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* The macro checks for "n <= 1" and not "n != 0" as js_bitscan_clz32(0) is |
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* undefined. |
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*/ |
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# define JS_CEILING_LOG2(_log2,_n) \ |
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JS_BEGIN_MACRO \ |
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unsigned int j_ = (unsigned int)(_n); \ |
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(_log2) = (j_ <= 1 ? 0 : 32 - js_bitscan_clz32(j_ - 1)); \ |
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JS_END_MACRO |
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#else |
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# define JS_CEILING_LOG2(_log2,_n) \ |
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JS_BEGIN_MACRO \ |
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JSUint32 j_ = (JSUint32)(_n); \ |
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(_log2) = 0; \ |
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if ((j_) & ((j_)-1)) \ |
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(_log2) += 1; \ |
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if ((j_) >> 16) \ |
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(_log2) += 16, (j_) >>= 16; \ |
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if ((j_) >> 8) \ |
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(_log2) += 8, (j_) >>= 8; \ |
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if ((j_) >> 4) \ |
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(_log2) += 4, (j_) >>= 4; \ |
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if ((j_) >> 2) \ |
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(_log2) += 2, (j_) >>= 2; \ |
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if ((j_) >> 1) \ |
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(_log2) += 1; \ |
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JS_END_MACRO |
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#endif |
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/* |
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** Macro version of JS_FloorLog2: Compute the log of the greatest power of |
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** 2 less than or equal to _n. The result is returned in _log2. |
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** |
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** This is equivalent to finding the highest set bit in the word. |
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*/ |
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#ifdef JS_HAS_BUILTIN_BITSCAN32 |
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/* |
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* Use js_bitscan_clz32 or count-leading-zeros to calculate floor(log2(_n)). |
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* Since js_bitscan_clz32(0) is undefined, the macro set the loweset bit to 1 |
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* to ensure 0 result when _n == 0. |
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*/ |
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# define JS_FLOOR_LOG2(_log2,_n) \ |
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JS_BEGIN_MACRO \ |
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(_log2) = 31 - js_bitscan_clz32(((unsigned int)(_n)) | 1); \ |
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JS_END_MACRO |
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#else |
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# define JS_FLOOR_LOG2(_log2,_n) \ |
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JS_BEGIN_MACRO \ |
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JSUint32 j_ = (JSUint32)(_n); \ |
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(_log2) = 0; \ |
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if ((j_) >> 16) \ |
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(_log2) += 16, (j_) >>= 16; \ |
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if ((j_) >> 8) \ |
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(_log2) += 8, (j_) >>= 8; \ |
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if ((j_) >> 4) \ |
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(_log2) += 4, (j_) >>= 4; \ |
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if ((j_) >> 2) \ |
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(_log2) += 2, (j_) >>= 2; \ |
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if ((j_) >> 1) \ |
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(_log2) += 1; \ |
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JS_END_MACRO |
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#endif |
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/* |
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* Internal function. |
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* Compute the log of the least power of 2 greater than or equal to n. |
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* This is a version of JS_CeilingLog2 that operates on jsuword with |
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* CPU-dependant size. |
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*/ |
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#define JS_CEILING_LOG2W(n) ((n) <= 1 ? 0 : 1 + JS_FLOOR_LOG2W((n) - 1)) |
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/* |
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* Internal function. |
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* Compute the log of the greatest power of 2 less than or equal to n. |
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* This is a version of JS_FloorLog2 that operates on jsuword with |
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* CPU-dependant size and requires that n != 0. |
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*/ |
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#define JS_FLOOR_LOG2W(n) (JS_ASSERT((n) != 0), js_FloorLog2wImpl(n)) |
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#if JS_BYTES_PER_WORD == 4 |
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# ifdef JS_HAS_BUILTIN_BITSCAN32 |
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# define js_FloorLog2wImpl(n) \ |
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((JSUword)(JS_BITS_PER_WORD - 1 - js_bitscan_clz32(n))) |
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# else |
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# define js_FloorLog2wImpl(n) ((JSUword)JS_FloorLog2(n)) |
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#endif |
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#elif JS_BYTES_PER_WORD == 8 |
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# ifdef JS_HAS_BUILTIN_BITSCAN64 |
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# define js_FloorLog2wImpl(n) \ |
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((JSUword)(JS_BITS_PER_WORD - 1 - js_bitscan_clz64(n))) |
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# else |
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extern JSUword js_FloorLog2wImpl(JSUword n); |
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# endif |
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#else |
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# error "NOT SUPPORTED" |
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#endif |
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/* |
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* Macros for rotate left. There is no rotate operation in the C Language so |
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* the construct (a << 4) | (a >> 28) is used instead. Most compilers convert |
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* this to a rotate instruction but some versions of MSVC don't without a |
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* little help. To get MSVC to generate a rotate instruction, we have to use |
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* the _rotl intrinsic and use a pragma to make _rotl inline. |
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* |
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* MSVC in VS2005 will do an inline rotate instruction on the above construct. |
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*/ |
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#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \ |
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defined(_M_X64)) |
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#include <stdlib.h> |
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#pragma intrinsic(_rotl) |
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#define JS_ROTATE_LEFT32(a, bits) _rotl(a, bits) |
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#else |
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#define JS_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits)))) |
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#endif |
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JS_END_EXTERN_C |
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#endif /* jsbit_h___ */ |
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