L4Re - L4 Runtime Environment
bitmap_cap_alloc
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1 // -*- Mode: C++ -*-
2 // vim:ft=cpp
3 /**
4  * \file bitmap_cap_alloc
5  * \brief Bitmap capability allocator
6  */
7 /*
8  * (c) 2008-2009 Adam Lackorzynski <adam@os.inf.tu-dresden.de>,
9  * Alexander Warg <warg@os.inf.tu-dresden.de>
10  * economic rights: Technische Universit├Ąt Dresden (Germany)
11  *
12  * This file is part of TUD:OS and distributed under the terms of the
13  * GNU General Public License 2.
14  * Please see the COPYING-GPL-2 file for details.
15  *
16  * As a special exception, you may use this file as part of a free software
17  * library without restriction. Specifically, if other files instantiate
18  * templates or use macros or inline functions from this file, or you compile
19  * this file and link it with other files to produce an executable, this
20  * file does not by itself cause the resulting executable to be covered by
21  * the GNU General Public License. This exception does not however
22  * invalidate any other reasons why the executable file might be covered by
23  * the GNU General Public License.
24  */
25 
26 #pragma once
27 
28 #include <l4/re/util/item_alloc>
29 #include <l4/sys/capability>
30 #include <l4/sys/task.h>
31 
32 namespace L4Re { namespace Util {
33 
34 /**
35  * \brief Capability allocator.
36  * \ingroup api_l4re_util
37  */
38 class Cap_alloc_base
39 {
40 private:
41  long _bias;
42  Item_alloc_base _items;
43 
44 public:
45  enum State { Free = 0, Allocated, Unknown };
46  Cap_alloc_base(long max, void *mem, long bias = 0)
47  throw() : _bias(bias), _items(max, mem) {}
48 
49  L4::Cap<void> alloc() throw()
50  {
51  long cap = _items.alloc();
52  if (cap < 0)
53  return L4::Cap<void>::Invalid;
54 
55  return L4::Cap<void>((cap + _bias) << L4_CAP_SHIFT);
56  }
57 
58  long hint() const { return _items.hint(); }
59 
60  /**
61  * \brief Allocate a capability slot.
62  */
63  template< typename T >
64  L4::Cap<T> alloc() throw()
65  { return L4::Cap<T>(alloc().cap()); }
66 
67  State is_allocated(L4::Cap<void> c) const throw()
68  {
69  long idx = (c.cap() >> L4_CAP_SHIFT);
70 
71  if (idx < _bias)
72  return Unknown;
73 
74  idx -= _bias;
75  return _items.is_allocated(idx) ? Allocated : Free;
76  }
77 
78  /**
79  * \brief Free a capability slot.
80  */
81  template< typename T>
82  void free(L4::Cap<T> const &cap, l4_cap_idx_t task = -1UL,
83  l4_umword_t unmap_flags = L4_FP_ALL_SPACES) throw()
84  {
85  long idx = (cap.cap() >> L4_CAP_SHIFT);
86  if (idx < _bias)
87  return;
88 
89  idx -= _bias;
90 
91  _items.free(idx);
92 
93  if (task != -1UL)
94  l4_task_unmap(task, cap.fpage(), unmap_flags | 2);
95  }
96 
97  // since we have no counters assume counter always > 0
98  void take(L4::Cap<void>) throw() {}
99  bool release(L4::Cap<void>, l4_cap_idx_t task = L4_INVALID_CAP,
100  unsigned unmap_flags = L4_FP_ALL_SPACES) throw()
101  { (void)task; (void)unmap_flags; return false; }
102 
103  long last() throw()
104  {
105  return _items.size() + _bias - 1;
106  }
107 };
108 
109 template< long Size >
110 class Cap_alloc : public Cap_alloc_base
111 {
112 private:
113  typename Bitmap_base::Word<Size>::Type _bits[Bitmap_base::Word<Size>::Size];
114 
115 public:
116  explicit Cap_alloc(long bias = 0) throw()
117  : Cap_alloc_base(Size, _bits, bias) {}
118 
119 };
120 
121 }
122 }