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/* -*- c++ -*- */
/*
* Copyright 2004,2007,2009 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 3, 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_BLOCK_H
#define INCLUDED_GR_BLOCK_H
#include <gr_basic_block.h>
/*!
* \brief The abstract base class for all 'terminal' processing blocks.
* \ingroup base_blk
*
* A signal processing flow is constructed by creating a tree of
* hierarchical blocks, which at any level may also contain terminal nodes
* that actually implement signal processing functions. This is the base
* class for all such leaf nodes.
* Blocks have a set of input streams and output streams. The
* input_signature and output_signature define the number of input
* streams and output streams respectively, and the type of the data
* items in each stream.
*
* Although blocks may consume data on each input stream at a
* different rate, all outputs streams must produce data at the same
* rate. That rate may be different from any of the input rates.
*
* User derived blocks override two methods, forecast and general_work,
* to implement their signal processing behavior. forecast is called
* by the system scheduler to determine how many items are required on
* each input stream in order to produce a given number of output
* items.
*
* general_work is called to perform the signal processing in the block.
* It reads the input items and writes the output items.
*/
class gr_block : public gr_basic_block {
public:
//! Magic return values from general_work
enum {
WORK_CALLED_PRODUCE = -2,
WORK_DONE = -1
};
virtual ~gr_block ();
/*!
* Assume block computes y_i = f(x_i, x_i-1, x_i-2, x_i-3...)
* History is the number of x_i's that are examined to produce one y_i.
* This comes in handy for FIR filters, where we use history to
* ensure that our input contains the appropriate "history" for the
* filter. History should be equal to the number of filter taps.
*/
unsigned history () const { return d_history; }
void set_history (unsigned history) { d_history = history; }
/*!
* \brief Return true if this block has a fixed input to output rate.
*
* If true, then fixed_rate_in_to_out and fixed_rate_out_to_in may be called.
*/
bool fixed_rate() const { return d_fixed_rate; }
// ----------------------------------------------------------------
// override these to define your behavior
// ----------------------------------------------------------------
/*!
* \brief Estimate input requirements given output request
*
* \param noutput_items number of output items to produce
* \param ninput_items_required number of input items required on each input stream
*
* Given a request to product \p noutput_items, estimate the number of
* data items required on each input stream. The estimate doesn't have
* to be exact, but should be close.
*/
virtual void forecast (int noutput_items,
gr_vector_int &ninput_items_required);
/*!
* \brief compute output items from input items
*
* \param noutput_items number of output items to write on each output stream
* \param ninput_items number of input items available on each input stream
* \param input_items vector of pointers to the input items, one entry per input stream
* \param output_items vector of pointers to the output items, one entry per output stream
*
* \returns number of items actually written to each output stream, or -1 on EOF.
* It is OK to return a value less than noutput_items. -1 <= return value <= noutput_items
*
* general_work must call consume or consume_each to indicate how many items
* were consumed on each input stream.
*/
virtual int general_work (int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items) = 0;
/*!
* \brief Called to enable drivers, etc for i/o devices.
*
* This allows a block to enable an associated driver to begin
* transfering data just before we start to execute the scheduler.
* The end result is that this reduces latency in the pipeline when
* dealing with audio devices, usrps, etc.
*/
virtual bool start();
/*!
* \brief Called to disable drivers, etc for i/o devices.
*/
virtual bool stop();
// ----------------------------------------------------------------
/*!
* \brief Constrain the noutput_items argument passed to forecast and general_work
*
* set_output_multiple causes the scheduler to ensure that the noutput_items
* argument passed to forecast and general_work will be an integer multiple
* of \param multiple The default value of output multiple is 1.
*/
void set_output_multiple (int multiple);
int output_multiple () const { return d_output_multiple; }
/*!
* \brief Tell the scheduler \p how_many_items of input stream \p which_input were consumed.
*/
void consume (int which_input, int how_many_items);
/*!
* \brief Tell the scheduler \p how_many_items were consumed on each input stream.
*/
void consume_each (int how_many_items);
/*!
* \brief Tell the scheduler \p how_many_items were produced on output stream \p which_output.
*
* If the block's general_work method calls produce, \p general_work must return WORK_CALLED_PRODUCE.
*/
void produce (int which_output, int how_many_items);
/*!
* \brief Set the approximate output rate / input rate
*
* Provide a hint to the buffer allocator and scheduler.
* The default relative_rate is 1.0
*
* decimators have relative_rates < 1.0
* interpolators have relative_rates > 1.0
*/
void set_relative_rate (double relative_rate);
/*!
* \brief return the approximate output rate / input rate
*/
double relative_rate () const { return d_relative_rate; }
/*
* The following two methods provide special case info to the
* scheduler in the event that a block has a fixed input to output
* ratio. gr_sync_block, gr_sync_decimator and gr_sync_interpolator
* override these. If you're fixed rate, subclass one of those.
*/
/*!
* \brief Given ninput samples, return number of output samples that will be produced.
* N.B. this is only defined if fixed_rate returns true.
* Generally speaking, you don't need to override this.
*/
virtual int fixed_rate_ninput_to_noutput(int ninput);
/*!
* \brief Given noutput samples, return number of input samples required to produce noutput.
* N.B. this is only defined if fixed_rate returns true.
* Generally speaking, you don't need to override this.
*/
virtual int fixed_rate_noutput_to_ninput(int noutput);
// ----------------------------------------------------------------------------
private:
int d_output_multiple;
double d_relative_rate; // approx output_rate / input_rate
gr_block_detail_sptr d_detail; // implementation details
unsigned d_history;
bool d_fixed_rate;
protected:
gr_block (const std::string &name,
gr_io_signature_sptr input_signature,
gr_io_signature_sptr output_signature);
void set_fixed_rate(bool fixed_rate){ d_fixed_rate = fixed_rate; }
// These are really only for internal use, but leaving them public avoids
// having to work up an ever-varying list of friends
public:
gr_block_detail_sptr detail () const { return d_detail; }
void set_detail (gr_block_detail_sptr detail) { d_detail = detail; }
};
typedef std::vector<gr_block_sptr> gr_block_vector_t;
typedef std::vector<gr_block_sptr>::iterator gr_block_viter_t;
inline gr_block_sptr cast_to_block_sptr(gr_basic_block_sptr p)
{
return boost::dynamic_pointer_cast<gr_block, gr_basic_block>(p);
}
std::ostream&
operator << (std::ostream& os, const gr_block *m);
#endif /* INCLUDED_GR_BLOCK_H */
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