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Annotation of sbbs/javascript/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: /*
        !             3:  * The contents of this file are subject to the Netscape Public
        !             4:  * License Version 1.1 (the "License"); you may not use this file
        !             5:  * except in compliance with the License. You may obtain a copy of
        !             6:  * the License at http://www.mozilla.org/NPL/
        !             7:  *
        !             8:  * Software distributed under the License is distributed on an "AS
        !             9:  * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
        !            10:  * implied. See the License for the specific language governing
        !            11:  * rights and limitations under the License.
        !            12:  *
        !            13:  * The Original Code is Mozilla Communicator client code, released
        !            14:  * March 31, 1998.
        !            15:  *
        !            16:  * The Initial Developer of the Original Code is Netscape
        !            17:  * Communications Corporation.  Portions created by Netscape are
        !            18:  * Copyright (C) 1998 Netscape Communications Corporation. All
        !            19:  * Rights Reserved.
        !            20:  *
        !            21:  * Contributor(s):
        !            22:  *
        !            23:  * Alternatively, the contents of this file may be used under the
        !            24:  * terms of the GNU Public License (the "GPL"), in which case the
        !            25:  * provisions of the GPL are applicable instead of those above.
        !            26:  * If you wish to allow use of your version of this file only
        !            27:  * under the terms of the GPL and not to allow others to use your
        !            28:  * version of this file under the NPL, indicate your decision by
        !            29:  * deleting the provisions above and replace them with the notice
        !            30:  * and other provisions required by the GPL.  If you do not delete
        !            31:  * the provisions above, a recipient may use your version of this
        !            32:  * file under either the NPL or the GPL.
        !            33:  */
        !            34: 
        !            35: #ifndef jsbit_h___
        !            36: #define jsbit_h___
        !            37: 
        !            38: #include "jstypes.h"
        !            39: JS_BEGIN_EXTERN_C
        !            40: 
        !            41: /*
        !            42: ** A jsbitmap_t is a long integer that can be used for bitmaps
        !            43: */
        !            44: typedef JSUword     jsbitmap_t;     /* NSPR name, a la Unix system types */
        !            45: typedef jsbitmap_t  jsbitmap;       /* JS-style scalar typedef name */
        !            46: 
        !            47: #define JS_TEST_BIT(_map,_bit) \
        !            48:     ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] & (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
        !            49: #define JS_SET_BIT(_map,_bit) \
        !            50:     ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |= (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
        !            51: #define JS_CLEAR_BIT(_map,_bit) \
        !            52:     ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &= ~(1L << ((_bit) & (JS_BITS_PER_WORD-1))))
        !            53: 
        !            54: /*
        !            55: ** Compute the log of the least power of 2 greater than or equal to n
        !            56: */
        !            57: extern JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 i);
        !            58: 
        !            59: /*
        !            60: ** Compute the log of the greatest power of 2 less than or equal to n
        !            61: */
        !            62: extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i);
        !            63: 
        !            64: /*
        !            65: ** Macro version of JS_CeilingLog2: Compute the log of the least power of
        !            66: ** 2 greater than or equal to _n. The result is returned in _log2.
        !            67: */
        !            68: #define JS_CEILING_LOG2(_log2,_n)                                             \
        !            69:     JS_BEGIN_MACRO                                                            \
        !            70:         JSUint32 j_ = (JSUint32)(_n);                                         \
        !            71:         (_log2) = 0;                                                          \
        !            72:         if ((j_) & ((j_)-1))                                                  \
        !            73:             (_log2) += 1;                                                     \
        !            74:         if ((j_) >> 16)                                                       \
        !            75:             (_log2) += 16, (j_) >>= 16;                                       \
        !            76:         if ((j_) >> 8)                                                        \
        !            77:             (_log2) += 8, (j_) >>= 8;                                         \
        !            78:         if ((j_) >> 4)                                                        \
        !            79:             (_log2) += 4, (j_) >>= 4;                                         \
        !            80:         if ((j_) >> 2)                                                        \
        !            81:             (_log2) += 2, (j_) >>= 2;                                         \
        !            82:         if ((j_) >> 1)                                                        \
        !            83:             (_log2) += 1;                                                     \
        !            84:     JS_END_MACRO
        !            85: 
        !            86: /*
        !            87: ** Macro version of JS_FloorLog2: Compute the log of the greatest power of
        !            88: ** 2 less than or equal to _n. The result is returned in _log2.
        !            89: **
        !            90: ** This is equivalent to finding the highest set bit in the word.
        !            91: */
        !            92: #define JS_FLOOR_LOG2(_log2,_n)                                               \
        !            93:     JS_BEGIN_MACRO                                                            \
        !            94:         JSUint32 j_ = (JSUint32)(_n);                                         \
        !            95:         (_log2) = 0;                                                          \
        !            96:         if ((j_) >> 16)                                                       \
        !            97:             (_log2) += 16, (j_) >>= 16;                                       \
        !            98:         if ((j_) >> 8)                                                        \
        !            99:             (_log2) += 8, (j_) >>= 8;                                         \
        !           100:         if ((j_) >> 4)                                                        \
        !           101:             (_log2) += 4, (j_) >>= 4;                                         \
        !           102:         if ((j_) >> 2)                                                        \
        !           103:             (_log2) += 2, (j_) >>= 2;                                         \
        !           104:         if ((j_) >> 1)                                                        \
        !           105:             (_log2) += 1;                                                     \
        !           106:     JS_END_MACRO
        !           107: 
        !           108: JS_END_EXTERN_C
        !           109: #endif /* jsbit_h___ */

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