/js/lib/Socket.IO-node/support/expresso/deps/jscoverage/js/jsbit.h

  1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  2/* ***** BEGIN LICENSE BLOCK *****
  3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  4 *
  5 * The contents of this file are subject to the Mozilla Public License Version
  6 * 1.1 (the "License"); you may not use this file except in compliance with
  7 * the License. You may obtain a copy of the License at
  8 * http://www.mozilla.org/MPL/
  9 *
 10 * Software distributed under the License is distributed on an "AS IS" basis,
 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 12 * for the specific language governing rights and limitations under the
 13 * License.
 14 *
 15 * The Original Code is Mozilla Communicator client code, released
 16 * March 31, 1998.
 17 *
 18 * The Initial Developer of the Original Code is
 19 * Netscape Communications Corporation.
 20 * Portions created by the Initial Developer are Copyright (C) 1998
 21 * the Initial Developer. All Rights Reserved.
 22 *
 23 * Contributor(s):
 24 *
 25 * Alternatively, the contents of this file may be used under the terms of
 26 * either of the GNU General Public License Version 2 or later (the "GPL"),
 27 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 28 * in which case the provisions of the GPL or the LGPL are applicable instead
 29 * of those above. If you wish to allow use of your version of this file only
 30 * under the terms of either the GPL or the LGPL, and not to allow others to
 31 * use your version of this file under the terms of the MPL, indicate your
 32 * decision by deleting the provisions above and replace them with the notice
 33 * and other provisions required by the GPL or the LGPL. If you do not delete
 34 * the provisions above, a recipient may use your version of this file under
 35 * the terms of any one of the MPL, the GPL or the LGPL.
 36 *
 37 * ***** END LICENSE BLOCK ***** */
 38
 39#ifndef jsbit_h___
 40#define jsbit_h___
 41
 42#include "jstypes.h"
 43#include "jsutil.h"
 44
 45JS_BEGIN_EXTERN_C
 46
 47/*
 48** A jsbitmap_t is a long integer that can be used for bitmaps
 49*/
 50typedef JSUword     jsbitmap_t;     /* NSPR name, a la Unix system types */
 51typedef jsbitmap_t  jsbitmap;       /* JS-style scalar typedef name */
 52
 53#define JS_BITMAP_SIZE(bits)    (JS_HOWMANY(bits, JS_BITS_PER_WORD) *         \
 54                                 sizeof(jsbitmap))
 55
 56#define JS_TEST_BIT(_map,_bit)  ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &      \
 57                                 ((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1))))
 58#define JS_SET_BIT(_map,_bit)   ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |=     \
 59                                 ((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1))))
 60#define JS_CLEAR_BIT(_map,_bit) ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &=     \
 61                                 ~((jsbitmap)1<<((_bit)&(JS_BITS_PER_WORD-1))))
 62
 63/*
 64** Compute the log of the least power of 2 greater than or equal to n
 65*/
 66extern JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 i);
 67
 68/*
 69** Compute the log of the greatest power of 2 less than or equal to n
 70*/
 71extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i);
 72
 73/*
 74 * Replace bit-scanning code sequences with CPU-specific instructions to
 75 * speedup calculations of ceiling/floor log2.
 76 *
 77 * With GCC 3.4 or later we can use __builtin_clz for that, see bug 327129.
 78 *
 79 * SWS: Added MSVC intrinsic bitscan support.  See bugs 349364 and 356856.
 80 */
 81#if defined(_WIN32) && (_MSC_VER >= 1300) && defined(_M_IX86)
 82
 83unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask);
 84unsigned char _BitScanReverse(unsigned long * Index, unsigned long Mask);
 85# pragma intrinsic(_BitScanForward,_BitScanReverse)
 86
 87__forceinline static int
 88__BitScanForward32(unsigned int val)
 89{
 90    unsigned long idx;
 91
 92    _BitScanForward(&idx, (unsigned long)val);
 93    return (int)idx;
 94}
 95__forceinline static int
 96__BitScanReverse32(unsigned int val)
 97{
 98    unsigned long idx;
 99
100    _BitScanReverse(&idx, (unsigned long)val);
101    return (int)(31-idx);
102}
103# define js_bitscan_ctz32(val)  __BitScanForward32(val)
104# define js_bitscan_clz32(val)  __BitScanReverse32(val)
105# define JS_HAS_BUILTIN_BITSCAN32
106
107#elif (__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
108
109# define js_bitscan_ctz32(val)  __builtin_ctz(val)
110# define js_bitscan_clz32(val)  __builtin_clz(val)
111# define JS_HAS_BUILTIN_BITSCAN32
112# if (JS_BYTES_PER_WORD == 8)
113#  define js_bitscan_ctz64(val)  __builtin_ctzll(val)
114#  define js_bitscan_clz64(val)  __builtin_clzll(val)
115#  define JS_HAS_BUILTIN_BITSCAN64
116# endif
117
118#endif
119
120/*
121** Macro version of JS_CeilingLog2: Compute the log of the least power of
122** 2 greater than or equal to _n. The result is returned in _log2.
123*/
124#ifdef JS_HAS_BUILTIN_BITSCAN32
125/*
126 * Use intrinsic function or count-leading-zeros to calculate ceil(log2(_n)).
127 * The macro checks for "n <= 1" and not "n != 0" as js_bitscan_clz32(0) is
128 * undefined.
129 */
130# define JS_CEILING_LOG2(_log2,_n)                                            \
131    JS_BEGIN_MACRO                                                            \
132        JS_STATIC_ASSERT(sizeof(unsigned int) == sizeof(JSUint32));           \
133        unsigned int j_ = (unsigned int)(_n);                                 \
134        (_log2) = (j_ <= 1 ? 0 : 32 - js_bitscan_clz32(j_ - 1));              \
135    JS_END_MACRO
136#else
137# define JS_CEILING_LOG2(_log2,_n)                                            \
138    JS_BEGIN_MACRO                                                            \
139        JSUint32 j_ = (JSUint32)(_n);                                         \
140        (_log2) = 0;                                                          \
141        if ((j_) & ((j_)-1))                                                  \
142            (_log2) += 1;                                                     \
143        if ((j_) >> 16)                                                       \
144            (_log2) += 16, (j_) >>= 16;                                       \
145        if ((j_) >> 8)                                                        \
146            (_log2) += 8, (j_) >>= 8;                                         \
147        if ((j_) >> 4)                                                        \
148            (_log2) += 4, (j_) >>= 4;                                         \
149        if ((j_) >> 2)                                                        \
150            (_log2) += 2, (j_) >>= 2;                                         \
151        if ((j_) >> 1)                                                        \
152            (_log2) += 1;                                                     \
153    JS_END_MACRO
154#endif
155
156/*
157** Macro version of JS_FloorLog2: Compute the log of the greatest power of
158** 2 less than or equal to _n. The result is returned in _log2.
159**
160** This is equivalent to finding the highest set bit in the word.
161*/
162#ifdef JS_HAS_BUILTIN_BITSCAN32
163/*
164 * Use js_bitscan_clz32 or count-leading-zeros to calculate floor(log2(_n)).
165 * Since js_bitscan_clz32(0) is undefined, the macro set the loweset bit to 1
166 * to ensure 0 result when _n == 0.
167 */
168# define JS_FLOOR_LOG2(_log2,_n)                                              \
169    JS_BEGIN_MACRO                                                            \
170        JS_STATIC_ASSERT(sizeof(unsigned int) == sizeof(JSUint32));           \
171        (_log2) = 31 - js_bitscan_clz32(((unsigned int)(_n)) | 1);            \
172    JS_END_MACRO
173#else
174# define JS_FLOOR_LOG2(_log2,_n)                                              \
175    JS_BEGIN_MACRO                                                            \
176        JSUint32 j_ = (JSUint32)(_n);                                         \
177        (_log2) = 0;                                                          \
178        if ((j_) >> 16)                                                       \
179            (_log2) += 16, (j_) >>= 16;                                       \
180        if ((j_) >> 8)                                                        \
181            (_log2) += 8, (j_) >>= 8;                                         \
182        if ((j_) >> 4)                                                        \
183            (_log2) += 4, (j_) >>= 4;                                         \
184        if ((j_) >> 2)                                                        \
185            (_log2) += 2, (j_) >>= 2;                                         \
186        if ((j_) >> 1)                                                        \
187            (_log2) += 1;                                                     \
188    JS_END_MACRO
189#endif
190
191/*
192 * Internal function.
193 * Compute the log of the least power of 2 greater than or equal to n.
194 * This is a version of JS_CeilingLog2 that operates on jsuword with
195 * CPU-dependant size.
196 */
197#define JS_CEILING_LOG2W(n) ((n) <= 1 ? 0 : 1 + JS_FLOOR_LOG2W((n) - 1))
198
199/*
200 * Internal function.
201 * Compute the log of the greatest power of 2 less than or equal to n.
202 * This is a version of JS_FloorLog2 that operates on jsuword with
203 * CPU-dependant size and requires that n != 0.
204 */
205#define JS_FLOOR_LOG2W(n) (JS_ASSERT((n) != 0), js_FloorLog2wImpl(n))
206
207#if JS_BYTES_PER_WORD == 4
208
209# ifdef JS_HAS_BUILTIN_BITSCAN32
210JS_STATIC_ASSERT(sizeof(unsigned) == sizeof(JSUword));
211#  define js_FloorLog2wImpl(n)                                                \
212    ((JSUword)(JS_BITS_PER_WORD - 1 - js_bitscan_clz32(n)))
213# else
214#  define js_FloorLog2wImpl(n) ((JSUword)JS_FloorLog2(n))
215#endif
216
217#elif JS_BYTES_PER_WORD == 8
218
219# ifdef JS_HAS_BUILTIN_BITSCAN64
220JS_STATIC_ASSERT(sizeof(unsigned long long) == sizeof(JSUword));
221#  define js_FloorLog2wImpl(n)                                                \
222    ((JSUword)(JS_BITS_PER_WORD - 1 - js_bitscan_clz64(n)))
223# else
224extern JSUword js_FloorLog2wImpl(JSUword n);
225# endif
226
227#else
228
229# error "NOT SUPPORTED"
230
231#endif
232
233/*
234 * Macros for rotate left. There is no rotate operation in the C Language so
235 * the construct (a << 4) | (a >> 28) is used instead. Most compilers convert
236 * this to a rotate instruction but some versions of MSVC don't without a
237 * little help.  To get MSVC to generate a rotate instruction, we have to use
238 * the _rotl intrinsic and use a pragma to make _rotl inline.
239 *
240 * MSVC in VS2005 will do an inline rotate instruction on the above construct.
241 */
242
243#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
244    defined(_M_X64))
245#include <stdlib.h>
246#pragma intrinsic(_rotl)
247#define JS_ROTATE_LEFT32(a, bits) _rotl(a, bits)
248#else
249#define JS_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
250#endif
251
252JS_END_EXTERN_C
253#endif /* jsbit_h___ */