gr_block Class Reference
[Signal Processing Blocks]

#include <gr_block.h>

Inheritance diagram for gr_block:

gr_align_on_samplenumbers_ss gr_clock_recovery_mm_cc gr_clock_recovery_mm_ff gr_dd_mpsk_sync_cc gr_fractional_interpolator gr_keep_one_in_n gr_nop gr_packed_to_unpacked_bb gr_packed_to_unpacked_ii gr_packed_to_unpacked_ss gr_rational_resampler_base_ccc gr_rational_resampler_base_ccf gr_rational_resampler_base_fcc gr_rational_resampler_base_fff gr_rational_resampler_base_fsf gr_rational_resampler_base_scc gr_simple_correlator gr_simple_framer gr_squelch_base_cc gr_squelch_base_ff gr_sync_block gr_test gr_unpacked_to_packed_bb gr_unpacked_to_packed_ii gr_unpacked_to_packed_ss trellis_metrics_c trellis_metrics_f trellis_metrics_i trellis_metrics_s trellis_siso_combined_f trellis_siso_f trellis_viterbi_b trellis_viterbi_combined_b trellis_viterbi_combined_i trellis_viterbi_combined_s trellis_viterbi_i trellis_viterbi_s

List of all members.


Detailed Description

The abstract base class for all signal processing blocks.

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.

Public Member Functions

virtual ~gr_block ()
std::string name () const
gr_io_signature_sptr input_signature () const
gr_io_signature_sptr output_signature () const
long unique_id () const
unsigned history () const
void set_history (unsigned history)
bool fixed_rate () const
 return true if this block has a fixed input to output rate
virtual void forecast (int noutput_items, gr_vector_int &ninput_items_required)
 Estimate input requirements given output request.
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
 compute output items from input items
virtual bool check_topology (int ninputs, int noutputs)
 Confirm that ninputs and noutputs is an acceptable combination.
virtual bool start ()
 Called to enable drivers, etc for i/o devices.
virtual bool stop ()
 Called to disable drivers, etc for i/o devices.
void set_output_multiple (int multiple)
 Constrain the noutput_items argument passed to forecast and general_work.
int output_multiple () const
void consume (int which_input, int how_many_items)
 Tell the scheduler how_many_items of input stream which_input were consumed.
void consume_each (int how_many_items)
 Tell the scheduler how_many_items were consumed on each input stream.
void set_relative_rate (double relative_rate)
 Set the approximate output rate / input rate.
double relative_rate () const
 return the approximate output rate / input rate
virtual int fixed_rate_ninput_to_noutput (int ninput)
 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_noutput_to_ninput (int noutput)
 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.
gr_block_detail_sptr detail () const
void set_detail (gr_block_detail_sptr detail)

Protected Member Functions

 gr_block (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature)
void set_input_signature (gr_io_signature_sptr iosig)
 may only be called during constructor
void set_output_signature (gr_io_signature_sptr iosig)
 may only be called during constructor
void set_fixed_rate (bool fixed_rate)


Constructor & Destructor Documentation

gr_block::~gr_block (  )  [virtual]

gr_block::gr_block ( const std::string &  name,
gr_io_signature_sptr  input_signature,
gr_io_signature_sptr  output_signature 
) [protected]


Member Function Documentation

std::string gr_block::name (  )  const [inline]

Referenced by _wrap_gr_block_name(), and operator<<().

gr_io_signature_sptr gr_block::input_signature (  )  const [inline]

gr_io_signature_sptr gr_block::output_signature (  )  const [inline]

long gr_block::unique_id (  )  const [inline]

Referenced by operator<<().

unsigned gr_block::history (  )  const [inline]

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.

Reimplemented in gr_rational_resampler_base_ccc, gr_rational_resampler_base_ccf, gr_rational_resampler_base_fcc, gr_rational_resampler_base_fff, gr_rational_resampler_base_fsf, and gr_rational_resampler_base_scc.

Referenced by gr_sync_interpolator::fixed_rate_ninput_to_noutout(), gr_sync_decimator::fixed_rate_ninput_to_noutput(), gr_sync_block::fixed_rate_ninput_to_noutput(), gr_sync_interpolator::fixed_rate_noutput_to_ninput(), gr_sync_decimator::fixed_rate_noutput_to_ninput(), gr_sync_block::fixed_rate_noutput_to_ninput(), gr_test::forecast(), gr_align_on_samplenumbers_ss::forecast(), and gr_test::general_work().

void gr_block::set_history ( unsigned  history  )  [inline]

bool gr_block::fixed_rate (  )  const [inline]

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.

void gr_block::forecast ( int  noutput_items,
gr_vector_int ninput_items_required 
) [virtual]

virtual int gr_block::general_work ( int  noutput_items,
gr_vector_int ninput_items,
gr_vector_const_void_star input_items,
gr_vector_void_star output_items 
) [pure virtual]

compute output items from input items

Parameters:
noutput_items number of output items to write on each output stream
ninput_items number of input items available on each input stream
input_items vector of pointers to the input items, one entry per input stream
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.

Implemented in gr_fractional_interpolator, gr_rational_resampler_base_ccc, gr_rational_resampler_base_ccf, gr_rational_resampler_base_fcc, gr_rational_resampler_base_fff, gr_rational_resampler_base_fsf, gr_rational_resampler_base_scc, gr_align_on_samplenumbers_ss, gr_clock_recovery_mm_cc, gr_clock_recovery_mm_ff, gr_dd_mpsk_sync_cc, gr_keep_one_in_n, gr_nop, gr_packed_to_unpacked_bb, gr_packed_to_unpacked_ii, gr_packed_to_unpacked_ss, gr_simple_correlator, gr_simple_framer, gr_squelch_base_cc, gr_squelch_base_ff, gr_sync_block, gr_sync_decimator, gr_sync_interpolator, gr_test, gr_unpacked_to_packed_bb, gr_unpacked_to_packed_ii, gr_unpacked_to_packed_ss, trellis_metrics_c, trellis_metrics_f, trellis_metrics_i, trellis_metrics_s, trellis_siso_combined_f, trellis_siso_f, trellis_viterbi_b, trellis_viterbi_combined_b, trellis_viterbi_combined_i, trellis_viterbi_combined_s, trellis_viterbi_i, and trellis_viterbi_s.

bool gr_block::check_topology ( int  ninputs,
int  noutputs 
) [virtual]

Confirm that ninputs and noutputs is an acceptable combination.

Parameters:
ninputs number of input streams connected
noutputs number of output streams connected
Returns:
true if this is a valid configuration for this block.
This function is called by the runtime system whenever the topology changes. Most classes do not need to override this. This check is in addition to the constraints specified by the input and output gr_io_signatures.

Reimplemented in gr_align_on_samplenumbers_ss, gr_chunks_to_symbols_bc, gr_chunks_to_symbols_bf, gr_chunks_to_symbols_ic, gr_chunks_to_symbols_if, gr_chunks_to_symbols_sc, gr_chunks_to_symbols_sf, gr_deinterleave, gr_interleave, gr_kludge_copy, gr_packed_to_unpacked_bb, gr_packed_to_unpacked_ii, gr_packed_to_unpacked_ss, gr_test, gr_unpacked_to_packed_bb, gr_unpacked_to_packed_ii, gr_unpacked_to_packed_ss, gr_oscope_sink_f, audio_alsa_sink, audio_alsa_source, audio_jack_sink, audio_jack_source, audio_osx_source, audio_portaudio_sink, and audio_portaudio_source.

bool gr_block::start ( void   )  [virtual]

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.

Reimplemented in audio_osx_sink, audio_osx_source, usrp1_sink_base, and usrp1_source_base.

Referenced by _wrap_gr_block_start().

bool gr_block::stop (  )  [virtual]

Called to disable drivers, etc for i/o devices.

Reimplemented in audio_osx_sink, audio_osx_source, usrp1_sink_base, and usrp1_source_base.

Referenced by _wrap_gr_block_stop().

void gr_block::set_output_multiple ( int  multiple  ) 

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

Parameters:
multiple The default value of output multiple is 1.

Referenced by audio_alsa_sink::audio_alsa_sink(), audio_alsa_source::audio_alsa_source(), audio_jack_sink::audio_jack_sink(), audio_jack_source::audio_jack_source(), audio_oss_sink::audio_oss_sink(), audio_oss_source::audio_oss_source(), gr_test::gr_test(), gr_sync_interpolator::set_interpolation(), video_sdl_sink_s::video_sdl_sink_s(), and video_sdl_sink_uc::video_sdl_sink_uc().

int gr_block::output_multiple (  )  const [inline]

void gr_block::consume ( int  which_input,
int  how_many_items 
)

Tell the scheduler how_many_items of input stream which_input were consumed.

Referenced by trellis_siso_f::general_work(), trellis_siso_combined_f::general_work(), gr_test::general_work(), gr_nop::general_work(), and gr_align_on_samplenumbers_ss::general_work().

void gr_block::consume_each ( int  how_many_items  ) 

void gr_block::set_relative_rate ( double  relative_rate  ) 

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

Referenced by gr_clock_recovery_mm_cc::gr_clock_recovery_mm_cc(), gr_clock_recovery_mm_ff::gr_clock_recovery_mm_ff(), gr_fractional_interpolator::gr_fractional_interpolator(), gr_test::gr_test(), gr_sync_decimator::set_decimation(), and gr_sync_interpolator::set_interpolation().

double gr_block::relative_rate (  )  const [inline]

return the approximate output rate / input rate

Referenced by gr_test::fixed_rate_ninput_to_noutput(), gr_test::fixed_rate_noutput_to_ninput(), and gr_test::forecast().

int gr_block::fixed_rate_ninput_to_noutput ( int  ninput  )  [virtual]

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.

Reimplemented in gr_sync_block, gr_sync_decimator, and gr_test.

int gr_block::fixed_rate_noutput_to_ninput ( int  noutput  )  [virtual]

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.

Reimplemented in gr_sync_block, gr_sync_decimator, gr_sync_interpolator, and gr_test.

void gr_block::set_input_signature ( gr_io_signature_sptr  iosig  )  [inline, protected]

void gr_block::set_output_signature ( gr_io_signature_sptr  iosig  )  [inline, protected]

void gr_block::set_fixed_rate ( bool  fixed_rate  )  [inline, protected]

gr_block_detail_sptr gr_block::detail (  )  const [inline]

void gr_block::set_detail ( gr_block_detail_sptr  detail  )  [inline]


The documentation for this class was generated from the following files:

Generated on Wed Oct 8 09:09:06 2008 for GNU Radio 3.0.4 by  doxygen 1.5.6