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Annotation of sbbs/include/mozilla/js/jsbit.h, revision 1.1

1.1     ! root        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: JS_BEGIN_EXTERN_C
        !            44: 
        !            45: /*
        !            46: ** A jsbitmap_t is a long integer that can be used for bitmaps
        !            47: */
        !            48: typedef JSUword     jsbitmap_t;     /* NSPR name, a la Unix system types */
        !            49: typedef jsbitmap_t  jsbitmap;       /* JS-style scalar typedef name */
        !            50: 
        !            51: #define JS_TEST_BIT(_map,_bit) \
        !            52:     ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] & (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
        !            53: #define JS_SET_BIT(_map,_bit) \
        !            54:     ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |= (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
        !            55: #define JS_CLEAR_BIT(_map,_bit) \
        !            56:     ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &= ~(1L << ((_bit) & (JS_BITS_PER_WORD-1))))
        !            57: 
        !            58: /*
        !            59: ** Compute the log of the least power of 2 greater than or equal to n
        !            60: */
        !            61: extern JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 i);
        !            62: 
        !            63: /*
        !            64: ** Compute the log of the greatest power of 2 less than or equal to n
        !            65: */
        !            66: extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i);
        !            67: 
        !            68: /*
        !            69: ** Macro version of JS_CeilingLog2: Compute the log of the least power of
        !            70: ** 2 greater than or equal to _n. The result is returned in _log2.
        !            71: */
        !            72: #define JS_CEILING_LOG2(_log2,_n)                                             \
        !            73:     JS_BEGIN_MACRO                                                            \
        !            74:         JSUint32 j_ = (JSUint32)(_n);                                         \
        !            75:         (_log2) = 0;                                                          \
        !            76:         if ((j_) & ((j_)-1))                                                  \
        !            77:             (_log2) += 1;                                                     \
        !            78:         if ((j_) >> 16)                                                       \
        !            79:             (_log2) += 16, (j_) >>= 16;                                       \
        !            80:         if ((j_) >> 8)                                                        \
        !            81:             (_log2) += 8, (j_) >>= 8;                                         \
        !            82:         if ((j_) >> 4)                                                        \
        !            83:             (_log2) += 4, (j_) >>= 4;                                         \
        !            84:         if ((j_) >> 2)                                                        \
        !            85:             (_log2) += 2, (j_) >>= 2;                                         \
        !            86:         if ((j_) >> 1)                                                        \
        !            87:             (_log2) += 1;                                                     \
        !            88:     JS_END_MACRO
        !            89: 
        !            90: /*
        !            91: ** Macro version of JS_FloorLog2: Compute the log of the greatest power of
        !            92: ** 2 less than or equal to _n. The result is returned in _log2.
        !            93: **
        !            94: ** This is equivalent to finding the highest set bit in the word.
        !            95: */
        !            96: #define JS_FLOOR_LOG2(_log2,_n)                                               \
        !            97:     JS_BEGIN_MACRO                                                            \
        !            98:         JSUint32 j_ = (JSUint32)(_n);                                         \
        !            99:         (_log2) = 0;                                                          \
        !           100:         if ((j_) >> 16)                                                       \
        !           101:             (_log2) += 16, (j_) >>= 16;                                       \
        !           102:         if ((j_) >> 8)                                                        \
        !           103:             (_log2) += 8, (j_) >>= 8;                                         \
        !           104:         if ((j_) >> 4)                                                        \
        !           105:             (_log2) += 4, (j_) >>= 4;                                         \
        !           106:         if ((j_) >> 2)                                                        \
        !           107:             (_log2) += 2, (j_) >>= 2;                                         \
        !           108:         if ((j_) >> 1)                                                        \
        !           109:             (_log2) += 1;                                                     \
        !           110:     JS_END_MACRO
        !           111: 
        !           112: JS_END_EXTERN_C
        !           113: #endif /* jsbit_h___ */

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