summaryrefslogtreecommitdiff
path: root/gnuradio-core/src/lib/runtime/gr_buffer.h
blob: 6f85f275ee77f94d27d1efe34a001afbc38232e0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
/* -*- c++ -*- */
/*
 * Copyright 2004 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * GNU Radio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifndef INCLUDED_GR_BUFFER_H
#define INCLUDED_GR_BUFFER_H

#include <gr_runtime.h>

class gr_vmcircbuf;

/*!
 * \brief Allocate a buffer that holds at least \p nitems of size \p sizeof_item.
 *
 * The total size of the buffer will be rounded up to a system
 * dependent boundary.  This is typically the system page size, but
 * under MS windows is 64KB.
 */
gr_buffer_sptr gr_make_buffer (int nitems, size_t sizeof_item);


/*!
 * \brief Single writer, multiple reader fifo.
 * \ingroup internal
 */
class gr_buffer {
 public:
  virtual ~gr_buffer ();

  /*!
   * \brief return number of items worth of space available for writing
   */
  int space_available () const;

  /*!
   * \brief return pointer to write buffer.
   *
   * The return value points at space that can hold at least
   * space_available() items.
   */
  void *write_pointer ();

  /*!
   * \brief tell buffer that we wrote \p nitems into it
   */
  void update_write_pointer (int nitems);


  void set_done (bool done)   { d_done = done; }
  bool done () const { return d_done; }

  // -------------------------------------------------------------------------

 private:

  friend class gr_buffer_reader;
  friend gr_buffer_sptr gr_make_buffer (int nitems, size_t sizeof_item);
  friend gr_buffer_reader_sptr gr_buffer_add_reader (gr_buffer_sptr buf, int history);

 protected:
  char				       *d_base;		// base address of buffer
  unsigned int	 			d_bufsize;	// in items
 private:
  gr_vmcircbuf			       *d_vmcircbuf;
  size_t	 			d_sizeof_item;	// in bytes
  unsigned int				d_write_index;	// in items [0,d_bufsize)
  std::vector<gr_buffer_reader *>	d_readers;
  bool					d_done;
  
  unsigned
  index_add (unsigned a, unsigned b)
  {
    unsigned s = a + b;

    if (s >= d_bufsize)
      s -= d_bufsize;

    assert (s < d_bufsize);
    return s;
  }

  unsigned
  index_sub (unsigned a, unsigned b)
  {
    int s = a - b;

    if (s < 0)
      s += d_bufsize;

    assert ((unsigned) s < d_bufsize);
    return s;
  }

  virtual bool allocate_buffer (int nitems, size_t sizeof_item);

  /*!
   * \brief constructor is private.  Use gr_make_buffer to create instances.
   *
   * Allocate a buffer that holds at least \p nitems of size \p sizeof_item.
   *
   * The total size of the buffer will be rounded up to a system
   * dependent boundary.  This is typically the system page size, but
   * under MS windows is 64KB.
   */
  gr_buffer (int nitems, size_t sizeof_item);

  /*!
   * \brief disassociate \p reader from this buffer
   */
  void drop_reader (gr_buffer_reader *reader);

};

//! create a new gr_buffer_reader and attach it to buffer \p buf
gr_buffer_reader_sptr gr_buffer_add_reader (gr_buffer_sptr buf, int history);

//! returns # of gr_buffers currently allocated
long gr_buffer_ncurrently_allocated ();


// ---------------------------------------------------------------------------

/*!
 * \brief How we keep track of the readers of a gr_buffer.
 * \ingroup internal
 */

class gr_buffer_reader {

 public:
  ~gr_buffer_reader ();

  /*!
   * \brief Return number of items available for reading.
   */
  int items_available () const;

  /*!
   * \brief Return maximum number of items that could ever be available for reading.
   * This is used as a sanity check in the scheduler to avoid looping forever.
   */
  int max_possible_items_available () const { return d_buffer->d_bufsize - 1; }

  /*!
   * \brief return pointer to read buffer.
   *
   * The return value points to items_available() number of items
   */
  const void *read_pointer ();

  /*
   * \brief tell buffer we read \p items from it
   */
  void update_read_pointer (int nitems);

  void set_done (bool done)   { d_buffer->set_done (done); }
  bool done () const { return d_buffer->done (); }

  // -------------------------------------------------------------------------

 private:

  friend class gr_buffer;
  friend gr_buffer_reader_sptr gr_buffer_add_reader (gr_buffer_sptr buf, int history);


  gr_buffer_sptr		d_buffer;
  unsigned int			d_read_index;	// in items [0,d->buffer.d_bufsize)

  //! constructor is private.  Use gr_buffer::add_reader to create instances
  gr_buffer_reader (gr_buffer_sptr buffer, unsigned int read_index);
};

//! returns # of gr_buffer_readers currently allocated
long gr_buffer_reader_ncurrently_allocated ();


#endif /* INCLUDED_GR_BUFFER_H */