/* -*- 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 /*! * \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_vector_t; typedef std::vector::iterator gr_block_viter_t; inline gr_block_sptr cast_to_block_sptr(gr_basic_block_sptr p) { return boost::dynamic_pointer_cast(p); } std::ostream& operator << (std::ostream& os, const gr_block *m); #endif /* INCLUDED_GR_BLOCK_H */