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/* -*- 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., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef INCLUDED_GR_BUFFER_H
#define INCLUDED_GR_BUFFER_H
#include <gr_runtime_types.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 nzero_preload);
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);
};
/*!
* \brief create a new gr_buffer_reader and attach it to buffer \p buf
* \param nzero_preload -- number of zero items to "preload" into buffer.
*/
gr_buffer_reader_sptr gr_buffer_add_reader (gr_buffer_sptr buf, int nzero_preload);
//! 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 buffer this reader reads from.
*/
gr_buffer_sptr buffer () const { return d_buffer; }
/*!
* \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 nzero_preload);
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 */
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