spike_generator.h

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/*
 *  spike_generator.h
 *
 *  This file is part of NEST.
 *
 *  Copyright (C) 2004 The NEST Initiative
 *
 *  NEST 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 of the License, or
 *  (at your option) any later version.
 *
 *  NEST 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 NEST.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef SPIKE_GENERATOR_H
#define SPIKE_GENERATOR_H


#include <vector>
#include "nest.h"
#include "event.h"
#include "node.h"
#include "scheduler.h"
#include "stimulating_device.h"
#include "connection.h"
#include "nest_time.h"
#include "network.h"

namespace nest
{
  /*BeginDocumentation
    Name: spike_generator - A device which generates spikes from an array with spike-times.

    Synopsis: spike_generator Create -> gid

    Description:
    A spike generator can be used to generate spikes at specific times
    which are given to the spike generator as an array.
    
    Spike times are given in milliseconds, and must be sorted with the
    earliest spike first. All spike times must be strictly in the future.
    Trying to set a spike time in the past or at the current time step,
    will cause a NEST error. Setting a spike time of 0.0 will also result
    in an error.

    Spike times may not coincide with a time step, i.e., are not a multiple
    of the simulation resolution. Three options control how spike times that 
    do not coincide with a step are handled (see examples below):

    Multiple occurences of the same time indicate that more than one
    event is to be generated at this particular time.

    Additionally, spike_weights can be set. This also is an array,
    which contains one weight value per spike time. If set, the spikes
    are delivered with the respective weight multiplied with the
    weight of the connection. To disable this functionality, the
    spike_weights array can be set to an empty array.

    /precise_times   default: false
       If false, spike times will be rounded to simulation steps, i.e., multiples
       of the resolution. The rounding is controlled by the two other flags.
       If true, spike times will not be rounded but represented exactly as a
       combination of step and offset. This should only be used if all neurons
       receiving the spike train can handle precise timing information. In this
       case, the other two options are ignored.

    /allow_offgrid_times   default: false
       If false, spike times will be rounded to the nearest step if they are 
       less than tic/2 from the step, otherwise NEST reports an error. 
       If true, spike times are rounded to the nearest step if within tic/2
       from the step, otherwise they are rounded up to the *end* of the step.

    /shift_now_spikes   default: false
       This option is mainly for use by the PyNN-NEST interface.
       If false, spike times rounded down to the current point in time will
       be considered in the past and ignored.
       If true, spike times that are rounded down to the current time step
       are shifted one time step into the future.

    Note that GetStatus will report the spike times that the spike_generator
    will actually use, i.e., for grid-based simulation the spike times rounded
    to the appropriate point on the time grid. This means that GetStatus may
    return different /spike_times values at different resolutions.

    Example:
    spikegenerator << /spike_times [1.0 2.0 3.0] >> SetStatus
    
    Instructs the spike generator to generate events at 1.0, 2.0, and
    3.0 milliseconds, relative to the device-timer origin.

    Example:
    Assume that NEST works with default resolution (step size) of 0.1ms
    and default tic length of 0.001ms. Then, spikes times not falling
    onto the grid will be handled as follows for different option settings:

    /spike_generator << /spike_times [1.0 1.9999 3.0001] >> Create
    ---> spikes at steps 10 (==1.0ms), 20 (==2.0ms) and 30 (==3.0ms)

    /spike_generator << /spike_times [1.0 1.05 3.0001] >> Create
    ---> error, spike time 1.05 not within tic/2 of step

    /spike_generator << /spike_times [1.0 1.05 3.0001] 
                        /allow_offgrid_times true >> Create
    ---> spikes at steps 10, 11 (mid-step time rounded up),
         30 (time within tic/2 of step moved to step)

    /spike_generator << /spike_times [1.0 1.05 3.0001] 
                        /precise_times true >> Create
    ---> spikes at step 10, offset 0.0; step 11, offset -0.05; 
         step 31, offset -0.0999

    Assume we have simulated 10.0ms and simulation times is thus 10.0 (step 100).
    Then, any spike times set, at this time, must be later than step 100.

    /spike_generator << /spike_times [10.0001] >> Create 
    ---> spike time is within tic/2 of step 100, rounded down to 100 thus
         not in the future, spike will not be emitted
    
    /spike_generator << /spike_times [10.0001] /precise_times true >> Create 
    ---> spike at step 101, offset -0.0999 is in the future

    /spike_generator << /spike_times [10.0001 11.0001] /shift_now_spikes true >> Create 
    ---> spike at step 101, spike shifted into the future, and spike at step 110, 
         not shifted, since it is in the future anyways
     

    Example:
    spikegenerator << /spike_times [1.0 2.0] /spike_weights [5.0 -8.0] >> SetStatus

    Instructs the spike generator to generate an event with weight 5.0
    at 1.0 ms, and an event with weight -8.0 at 2.0 ms, relative to
    the device-timer origin.

    spikegenerator << /spike_weights [] >> SetStatus

    Instructs the spike generator to generate events at 1.0, 2.0, and
    3.0 milliseconds, and use the weight of the connection.

    Parameters:
    The following properties can be set in the status dictionary.

     origin         double - Time origin for device timer in ms
     start          double - earliest possible time stamp of a spike to be emitted in ms
     stop           double - earliest time stamp of a potential spike event that is not emitted in ms 
     spike_times    double array - spike-times in ms
         spike_weights  double array - corrsponding spike-weights, the unit depends on the receiver
         precise_times        bool - see above
         allow_offgrid_spikes bool - see above
         shift_now_spikes     bool - see above

    Sends: SpikeEvent
         
    Author: Gewaltig, Diesmann, Eppler

    SeeAlso: Device, StimulatingDevice, testsuite::test_spike_generator
  */
  
  class spike_generator : public Node
  {
    
  public:    
    spike_generator();
    spike_generator(const spike_generator&);

    bool has_proxies() const {return false;} 

    port send_test_event(Node&, rport, synindex, bool);
    void get_status(DictionaryDatum &) const;
    void set_status(const DictionaryDatum &);

    using Node::event_hook;
    void event_hook(DSSpikeEvent&);

  private:
    
    void init_state_(const Node&);
    void init_buffers_();
    void calibrate();
    
    void update(Time const &, const long_t, const long_t);

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

    struct State_ {
      size_t position_;  

      State_();  
    };

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

    struct Parameters_ {

      std::vector<Time> spike_stamps_;    
      std::vector<double> spike_offsets_; 

      std::vector<double> spike_weights_;  

      bool precise_times_;           

      bool allow_offgrid_spikes_;    

      bool shift_now_spikes_;

      Parameters_();  
      Parameters_(const Parameters_&);  

      void get(DictionaryDatum&) const;  
      
      void set(const DictionaryDatum&, State_&, const Time&, const Time&);  

      void assert_valid_spike_time_and_insert_(double, const Time&, const Time&);
    };
        
    // ------------------------------------------------------------

    StimulatingDevice<SpikeEvent> device_;
    
    Parameters_ P_;
    State_      S_;
  };

inline
port spike_generator::send_test_event(Node& target, rport receptor_type, synindex syn_id, bool dummy_target)
{
    device_.enforce_single_syn_type(syn_id);

    if ( dummy_target )
    {
      DSSpikeEvent e;
      e.set_sender(*this);
      return target.handles_test_event(e, receptor_type);
    }
    else
    {
      SpikeEvent e;
      e.set_sender(*this);
      return target.handles_test_event(e, receptor_type);
    }
}

inline
void spike_generator::get_status(DictionaryDatum &d) const
{
  P_.get(d);
  device_.get_status(d);
}

inline
void spike_generator::set_status(const DictionaryDatum &d)
{
  Parameters_ ptmp = P_;  // temporary copy in case of errors

  // To detect "now" spikes and shift them, we need the origin. In case
  // it is set in this call, we need to extract it explicitly here.
  Time origin;
  double_t v;
  if ( updateValue<double_t>(d, names::origin, v) )
    origin = Time::ms(v);
  else
    origin = device_.get_origin();
  ptmp.set(d, S_, origin, network()->get_time());        // throws if BadProperty

  // We now know that ptmp is consistent. We do not write it back
  // to P_ before we are also sure that the properties to be set
  // in the parent class are internally consistent.
  device_.set_status(d);

  // if we get here, temporary contains consistent set of properties
  P_ = ptmp;
}


} // namespace

#endif /* #ifndef SPIKE_GENERATOR_H */