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Contents of /trunk/js/jsbit.h

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Update SpiderMonkey from Firefox 3.6rc1.

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
45 JS_BEGIN_EXTERN_C
46
47 /*
48 ** A jsbitmap_t is a long integer that can be used for bitmaps
49 */
50 typedef JSUword jsbitmap_t; /* NSPR name, a la Unix system types */
51 typedef 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 */
66 extern 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 */
71 extern 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) || defined(_M_AMD64) || defined(_M_X64))
82
83 unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask);
84 unsigned 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 #if defined(_M_AMD64) || defined(_M_X64)
108 unsigned char _BitScanForward64(unsigned long * Index, unsigned __int64 Mask);
109 unsigned char _BitScanReverse64(unsigned long * Index, unsigned __int64 Mask);
110 # pragma intrinsic(_BitScanForward64,_BitScanReverse64)
111
112 __forceinline static int
113 __BitScanForward64(unsigned __int64 val)
114 {
115 unsigned long idx;
116
117 _BitScanForward64(&idx, val);
118 return (int)idx;
119 }
120 __forceinline static int
121 __BitScanReverse64(unsigned __int64 val)
122 {
123 unsigned long idx;
124
125 _BitScanReverse64(&idx, val);
126 return (int)(63-idx);
127 }
128 # define js_bitscan_ctz64(val) __BitScanForward64(val)
129 # define js_bitscan_clz64(val) __BitScanReverse64(val)
130 # define JS_HAS_BUILTIN_BITSCAN64
131 #endif
132 #elif (__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
133
134 # define js_bitscan_ctz32(val) __builtin_ctz(val)
135 # define js_bitscan_clz32(val) __builtin_clz(val)
136 # define JS_HAS_BUILTIN_BITSCAN32
137 # if (JS_BYTES_PER_WORD == 8)
138 # define js_bitscan_ctz64(val) __builtin_ctzll(val)
139 # define js_bitscan_clz64(val) __builtin_clzll(val)
140 # define JS_HAS_BUILTIN_BITSCAN64
141 # endif
142
143 #endif
144
145 /*
146 ** Macro version of JS_CeilingLog2: Compute the log of the least power of
147 ** 2 greater than or equal to _n. The result is returned in _log2.
148 */
149 #ifdef JS_HAS_BUILTIN_BITSCAN32
150 /*
151 * Use intrinsic function or count-leading-zeros to calculate ceil(log2(_n)).
152 * The macro checks for "n <= 1" and not "n != 0" as js_bitscan_clz32(0) is
153 * undefined.
154 */
155 # define JS_CEILING_LOG2(_log2,_n) \
156 JS_BEGIN_MACRO \
157 unsigned int j_ = (unsigned int)(_n); \
158 (_log2) = (j_ <= 1 ? 0 : 32 - js_bitscan_clz32(j_ - 1)); \
159 JS_END_MACRO
160 #else
161 # define JS_CEILING_LOG2(_log2,_n) \
162 JS_BEGIN_MACRO \
163 JSUint32 j_ = (JSUint32)(_n); \
164 (_log2) = 0; \
165 if ((j_) & ((j_)-1)) \
166 (_log2) += 1; \
167 if ((j_) >> 16) \
168 (_log2) += 16, (j_) >>= 16; \
169 if ((j_) >> 8) \
170 (_log2) += 8, (j_) >>= 8; \
171 if ((j_) >> 4) \
172 (_log2) += 4, (j_) >>= 4; \
173 if ((j_) >> 2) \
174 (_log2) += 2, (j_) >>= 2; \
175 if ((j_) >> 1) \
176 (_log2) += 1; \
177 JS_END_MACRO
178 #endif
179
180 /*
181 ** Macro version of JS_FloorLog2: Compute the log of the greatest power of
182 ** 2 less than or equal to _n. The result is returned in _log2.
183 **
184 ** This is equivalent to finding the highest set bit in the word.
185 */
186 #ifdef JS_HAS_BUILTIN_BITSCAN32
187 /*
188 * Use js_bitscan_clz32 or count-leading-zeros to calculate floor(log2(_n)).
189 * Since js_bitscan_clz32(0) is undefined, the macro set the loweset bit to 1
190 * to ensure 0 result when _n == 0.
191 */
192 # define JS_FLOOR_LOG2(_log2,_n) \
193 JS_BEGIN_MACRO \
194 (_log2) = 31 - js_bitscan_clz32(((unsigned int)(_n)) | 1); \
195 JS_END_MACRO
196 #else
197 # define JS_FLOOR_LOG2(_log2,_n) \
198 JS_BEGIN_MACRO \
199 JSUint32 j_ = (JSUint32)(_n); \
200 (_log2) = 0; \
201 if ((j_) >> 16) \
202 (_log2) += 16, (j_) >>= 16; \
203 if ((j_) >> 8) \
204 (_log2) += 8, (j_) >>= 8; \
205 if ((j_) >> 4) \
206 (_log2) += 4, (j_) >>= 4; \
207 if ((j_) >> 2) \
208 (_log2) += 2, (j_) >>= 2; \
209 if ((j_) >> 1) \
210 (_log2) += 1; \
211 JS_END_MACRO
212 #endif
213
214 /*
215 * Internal function.
216 * Compute the log of the least power of 2 greater than or equal to n.
217 * This is a version of JS_CeilingLog2 that operates on jsuword with
218 * CPU-dependant size.
219 */
220 #define JS_CEILING_LOG2W(n) ((n) <= 1 ? 0 : 1 + JS_FLOOR_LOG2W((n) - 1))
221
222 /*
223 * Internal function.
224 * Compute the log of the greatest power of 2 less than or equal to n.
225 * This is a version of JS_FloorLog2 that operates on jsuword with
226 * CPU-dependant size and requires that n != 0.
227 */
228 #define JS_FLOOR_LOG2W(n) (JS_ASSERT((n) != 0), js_FloorLog2wImpl(n))
229
230 #if JS_BYTES_PER_WORD == 4
231
232 # ifdef JS_HAS_BUILTIN_BITSCAN32
233 # define js_FloorLog2wImpl(n) \
234 ((JSUword)(JS_BITS_PER_WORD - 1 - js_bitscan_clz32(n)))
235 # else
236 # define js_FloorLog2wImpl(n) ((JSUword)JS_FloorLog2(n))
237 #endif
238
239 #elif JS_BYTES_PER_WORD == 8
240
241 # ifdef JS_HAS_BUILTIN_BITSCAN64
242 # define js_FloorLog2wImpl(n) \
243 ((JSUword)(JS_BITS_PER_WORD - 1 - js_bitscan_clz64(n)))
244 # else
245 extern JSUword js_FloorLog2wImpl(JSUword n);
246 # endif
247
248 #else
249
250 # error "NOT SUPPORTED"
251
252 #endif
253
254 /*
255 * Macros for rotate left. There is no rotate operation in the C Language so
256 * the construct (a << 4) | (a >> 28) is used instead. Most compilers convert
257 * this to a rotate instruction but some versions of MSVC don't without a
258 * little help. To get MSVC to generate a rotate instruction, we have to use
259 * the _rotl intrinsic and use a pragma to make _rotl inline.
260 *
261 * MSVC in VS2005 will do an inline rotate instruction on the above construct.
262 */
263
264 #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64) || \
265 defined(_M_X64))
266 #include <stdlib.h>
267 #pragma intrinsic(_rotl)
268 #define JS_ROTATE_LEFT32(a, bits) _rotl(a, bits)
269 #else
270 #define JS_ROTATE_LEFT32(a, bits) (((a) << (bits)) | ((a) >> (32 - (bits))))
271 #endif
272
273 JS_END_EXTERN_C
274 #endif /* jsbit_h___ */

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