third_party/npapi/npspy/extern/nspr/prbit.h

   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 Mozilla 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/MPL/
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  10  * implied. See the License for the specific language governing
  11  * rights and limitations under the License.
  12  *
  13  * The Original Code is the Netscape Portable Runtime (NSPR).
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  15  * The Initial Developer of the Original Code is Netscape
  16  * Communications Corporation.  Portions created by Netscape are
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  22  * Alternatively, the contents of this file may be used under the
  23  * terms of the GNU General Public License Version 2 or later (the
  24  * "GPL"), in which case the provisions of the GPL are applicable
  25  * instead of those above.  If you wish to allow use of your
  26  * version of this file only under the terms of the GPL and not to
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  28  * indicate your decision by deleting the provisions above and
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  30  * the GPL.  If you do not delete the provisions above, a recipient
  31  * may use your version of this file under either the MPL or the
  32  * GPL.
  33  */
  34
  35 #ifndef prbit_h___
  36 #define prbit_h___
  37
  38 #include "prtypes.h"
  39 PR_BEGIN_EXTERN_C
  40
  41 /*
  42 ** A prbitmap_t is a long integer that can be used for bitmaps
  43 */
  44 typedef unsigned long prbitmap_t;
  45
  46 #define PR_TEST_BIT(_map,_bit) \
  47     ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
  48 #define PR_SET_BIT(_map,_bit) \
  49     ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1))))
  50 #define PR_CLEAR_BIT(_map,_bit) \
  51     ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1))))
  52
  53 /*
  54 ** Compute the log of the least power of 2 greater than or equal to n
  55 */
  56 NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i);
  57
  58 /*
  59 ** Compute the log of the greatest power of 2 less than or equal to n
  60 */
  61 NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i);
  62
  63 /*
  64 ** Macro version of PR_CeilingLog2: Compute the log of the least power of
  65 ** 2 greater than or equal to _n. The result is returned in _log2.
  66 */
  67 #define PR_CEILING_LOG2(_log2,_n)   \
  68   PR_BEGIN_MACRO                    \
  69     PRUint32 j_ = (PRUint32)(_n);       \
  70     (_log2) = 0;                    \
  71     if ((j_) & ((j_)-1))            \
  72         (_log2) += 1;               \
  73     if ((j_) >> 16)                 \
  74         (_log2) += 16, (j_) >>= 16; \
  75     if ((j_) >> 8)                  \
  76         (_log2) += 8, (j_) >>= 8;   \
  77     if ((j_) >> 4)                  \
  78         (_log2) += 4, (j_) >>= 4;   \
  79     if ((j_) >> 2)                  \
  80         (_log2) += 2, (j_) >>= 2;   \
  81     if ((j_) >> 1)                  \
  82         (_log2) += 1;               \
  83   PR_END_MACRO
  84
  85 /*
  86 ** Macro version of PR_FloorLog2: Compute the log of the greatest power of
  87 ** 2 less than or equal to _n. The result is returned in _log2.
  88 **
  89 ** This is equivalent to finding the highest set bit in the word.
  90 */
  91 #define PR_FLOOR_LOG2(_log2,_n)   \
  92   PR_BEGIN_MACRO                    \
  93     PRUint32 j_ = (PRUint32)(_n);       \
  94     (_log2) = 0;                    \
  95     if ((j_) >> 16)                 \
  96         (_log2) += 16, (j_) >>= 16; \
  97     if ((j_) >> 8)                  \
  98         (_log2) += 8, (j_) >>= 8;   \
  99     if ((j_) >> 4)                  \
 100         (_log2) += 4, (j_) >>= 4;   \
 101     if ((j_) >> 2)                  \
 102         (_log2) += 2, (j_) >>= 2;   \
 103     if ((j_) >> 1)                  \
 104         (_log2) += 1;               \
 105   PR_END_MACRO
 106
 107 PR_END_EXTERN_C
 108 #endif /* prbit_h___ */