headers/private/shared/binary-utils.h

   1 /*
   2  * Copyright 2009, Haiku, Inc. All Rights Reserved.
   3  * Distributed under the terms of the MIT License.
   4  *
   5  * Authors:
   6  *              Brecht Machiels, brecht@mos6581.org
   7  */
   8
   9 #ifndef _BINARY_UTILS_H
  10 #define _BINARY_UTILS_H
  11
  12
  13 /* macro for a one-bit bitmask
  14 */
  15
  16 #define BIT(n)  (1ULL << n)
  17
  18 /* macro/templates to create bitmasks
  19 */
  20
  21 #define BITMASK(high, low)      ((unsigned long long)(BitMask<high, low>::value))
  22
  23 template<int h, int l>
  24 struct BitMask
  25 {
  26         enum { value = (BitMask<h-l-1,0>::value +
  27                 (1ULL << h - l)) << l };
  28 };
  29
  30
  31 template<>
  32 struct BitMask<-1,0>
  33 {
  34         enum { value = 0ULL };
  35 };
  36
  37
  38 /* macro/templates to enter binary constants
  39 */
  40
  41 #define BINARY(binstring)       ((unsigned long long)(Binary<0##binstring>::value))
  42
  43 // http://www.eptacom.net/pubblicazioni/pub_eng/binary.html
  44 template<const unsigned long long N> struct Binary
  45 {
  46         enum { value = (N % 8ULL) + 2ULL * Binary<N / 8ULL>::value };
  47 };
  48
  49
  50 template<>
  51 struct Binary<0>
  52 {
  53         enum { value = 0ULL } ;
  54 };
  55
  56
  57 /* macro/templates to determine offset
  58
  59    NOTE: broken for high bit indices
  60 */
  61
  62 #define MASKOFFSET(mask)        (MaskOffset<mask, (mask & 1UL)>::count)
  63
  64 template<const unsigned long mask, unsigned int firstBit>
  65 struct MaskOffset
  66 {
  67         enum { count = MaskOffset<(mask >> 1), ((mask >> 1) & 1UL)>::count + 1 };
  68 };
  69
  70
  71 template<const unsigned long mask>
  72 struct MaskOffset<mask, 1>
  73 {
  74         enum { count = 0 };
  75 };
  76
  77 #endif // _BINARY_UTILS_H
  78