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GNU Radio Manual and C++ API Reference 3.10.5.1
The Free & Open Software Radio Ecosystem
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GNU Radio Manual and C++ API Reference 3.10.5.1
The Free & Open Software Radio Ecosystem
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Header/Payload demuxer (HPD). More...
#include <gnuradio/digital/header_payload_demux.h>
Public Types | |
| typedef std::shared_ptr< header_payload_demux > | sptr |
 Public Types inherited from gr::block | |
| enum | work_return_t { WORK_CALLED_PRODUCE = -2 , WORK_DONE = -1 } |
| Magic return values from general_work. More... | |
| enum | tag_propagation_policy_t { TPP_DONT = 0 , TPP_ALL_TO_ALL = 1 , TPP_ONE_TO_ONE = 2 , TPP_CUSTOM = 3 } |
| enum to represent different tag propagation policies. More... | |
Static Public Member Functions | |
| static sptr | make (const int header_len, const int items_per_symbol=1, const int guard_interval=0, const std::string &length_tag_key="frame_len", const std::string &trigger_tag_key="", const bool output_symbols=false, const size_t itemsize=sizeof(gr_complex), const std::string &timing_tag_key="", const double samp_rate=1.0, const std::vector< std::string > &special_tags=std::vector< std::string >(), const size_t header_padding=0) |
Additional Inherited Members | |
| Public Member Functions inherited from gr::block | |
| ~block () override | |
| unsigned | history () const |
| void | set_history (unsigned history) |
| void | declare_sample_delay (int which, unsigned delay) |
| void | declare_sample_delay (unsigned delay) |
| unsigned | sample_delay (int which) const |
| bool | fixed_rate () const |
| Return true if this block has a fixed input to output rate. More... | |
| virtual void | forecast (int noutput_items, gr_vector_int &ninput_items_required) |
| Estimate input requirements given output request. More... | |
| 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) |
| compute output items from input items More... | |
| virtual bool | start () |
| Called to enable drivers, etc for i/o devices. More... | |
| virtual bool | stop () |
| Called to disable drivers, etc for i/o devices. More... | |
| void | set_output_multiple (int multiple) |
| Constrain the noutput_items argument passed to forecast and general_work. More... | |
| int | output_multiple () const |
| bool | output_multiple_set () const |
| void | set_alignment (int multiple) |
| Constrains buffers to work on a set item alignment (for SIMD) More... | |
| int | alignment () const |
| void | set_unaligned (int na) |
| int | unaligned () const |
| void | set_is_unaligned (bool u) |
| bool | is_unaligned () const |
| void | consume (int which_input, int how_many_items) |
Tell the scheduler how_many_items of input stream which_input were consumed. More... | |
| void | consume_each (int how_many_items) |
Tell the scheduler how_many_items were consumed on each input stream. More... | |
| void | produce (int which_output, int how_many_items) |
Tell the scheduler how_many_items were produced on output stream which_output. More... | |
| void | set_relative_rate (double relative_rate) |
| Set the approximate output rate / input rate. More... | |
| void | set_inverse_relative_rate (double inverse_relative_rate) |
| Set the approximate output rate / input rate using its reciprocal. More... | |
| void | set_relative_rate (uint64_t interpolation, uint64_t decimation) |
| Set the approximate output rate / input rate as an integer ratio. More... | |
| double | relative_rate () const |
| return the approximate output rate / input rate More... | |
| uint64_t | relative_rate_i () const |
| return the numerator, or interpolation rate, of the approximate output rate / input rate More... | |
| uint64_t | relative_rate_d () const |
| return the denominator, or decimation rate, of the approximate output rate / input rate More... | |
| mpq_class & | mp_relative_rate () |
| return a reference to the multiple precision rational representation of the approximate output rate / input rate More... | |
| 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. More... | |
| 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. More... | |
| uint64_t | nitems_read (unsigned int which_input) |
| Return the number of items read on input stream which_input. More... | |
| uint64_t | nitems_written (unsigned int which_output) |
| Return the number of items written on output stream which_output. More... | |
| tag_propagation_policy_t | tag_propagation_policy () |
| Asks for the policy used by the scheduler to moved tags downstream. More... | |
| void | set_tag_propagation_policy (tag_propagation_policy_t p) |
| Set the policy by the scheduler to determine how tags are moved downstream. More... | |
| int | min_noutput_items () const |
| Return the minimum number of output items this block can produce during a call to work. More... | |
| void | set_min_noutput_items (int m) |
| Set the minimum number of output items this block can produce during a call to work. More... | |
| int | max_noutput_items () |
| Return the maximum number of output items this block will handle during a call to work. More... | |
| void | set_max_noutput_items (int m) |
| Set the maximum number of output items this block will handle during a call to work. More... | |
| void | unset_max_noutput_items () |
| Clear the switch for using the max_noutput_items value of this block. More... | |
| bool | is_set_max_noutput_items () |
| Ask the block if the flag is or is not set to use the internal value of max_noutput_items during a call to work. More... | |
| void | expand_minmax_buffer (int port) |
| long | max_output_buffer (size_t i) |
Returns max buffer size on output port i. More... | |
| void | set_max_output_buffer (long max_output_buffer) |
| Request limit on max buffer size on all output ports. More... | |
| void | set_max_output_buffer (int port, long max_output_buffer) |
Request limit on max buffer size on output port port. More... | |
| long | min_output_buffer (size_t i) |
Returns min buffer size on output port i. More... | |
| void | set_min_output_buffer (long min_output_buffer) |
| Request limit on the minimum buffer size on all output ports. More... | |
| void | set_min_output_buffer (int port, long min_output_buffer) |
Request limit on min buffer size on output port port. More... | |
| void | set_blkd_input_timer_value (unsigned int timer_value_ms) |
DEPRECATED Configure the timer set when input is blocked port. More... | |
| unsigned int | blkd_input_timer_value () |
| DEPRECATED Returns timer value set when input is blocked. More... | |
| void | allocate_detail (int ninputs, int noutputs, const std::vector< int > &downstream_max_nitems_vec, const std::vector< uint64_t > &downstream_lcm_nitems_vec, const std::vector< uint32_t > &downstream_max_out_mult_vec) |
| Allocate the block_detail and necessary output buffers for this block. More... | |
| buffer_sptr | replace_buffer (size_t src_port, size_t dst_port, block_sptr block_owner) |
| Replace the block's buffer with a new one owned by the block_owner parameter. More... | |
| float | pc_noutput_items () |
| Gets instantaneous noutput_items performance counter. More... | |
| float | pc_noutput_items_avg () |
| Gets average noutput_items performance counter. More... | |
| float | pc_noutput_items_var () |
| Gets variance of noutput_items performance counter. More... | |
| float | pc_nproduced () |
| Gets instantaneous num items produced performance counter. More... | |
| float | pc_nproduced_avg () |
| Gets average num items produced performance counter. More... | |
| float | pc_nproduced_var () |
| Gets variance of num items produced performance counter. More... | |
| float | pc_input_buffers_full (int which) |
Gets instantaneous fullness of which input buffer. More... | |
| float | pc_input_buffers_full_avg (int which) |
Gets average fullness of which input buffer. More... | |
| float | pc_input_buffers_full_var (int which) |
Gets variance of fullness of which input buffer. More... | |
| std::vector< float > | pc_input_buffers_full () |
| Gets instantaneous fullness of all input buffers. More... | |
| std::vector< float > | pc_input_buffers_full_avg () |
| Gets average fullness of all input buffers. More... | |
| std::vector< float > | pc_input_buffers_full_var () |
| Gets variance of fullness of all input buffers. More... | |
| float | pc_output_buffers_full (int which) |
Gets instantaneous fullness of which output buffer. More... | |
| float | pc_output_buffers_full_avg (int which) |
Gets average fullness of which output buffer. More... | |
| float | pc_output_buffers_full_var (int which) |
Gets variance of fullness of which output buffer. More... | |
| std::vector< float > | pc_output_buffers_full () |
| Gets instantaneous fullness of all output buffers. More... | |
| std::vector< float > | pc_output_buffers_full_avg () |
| Gets average fullness of all output buffers. More... | |
| std::vector< float > | pc_output_buffers_full_var () |
| Gets variance of fullness of all output buffers. More... | |
| float | pc_work_time () |
| Gets instantaneous clock cycles spent in work. More... | |
| float | pc_work_time_avg () |
| Gets average clock cycles spent in work. More... | |
| float | pc_work_time_var () |
| Gets average clock cycles spent in work. More... | |
| float | pc_work_time_total () |
| Gets total clock cycles spent in work. More... | |
| float | pc_throughput_avg () |
| Gets average throughput. More... | |
| void | reset_perf_counters () |
| Resets the performance counters. More... | |
| void | setup_pc_rpc () |
| Sets up export of perf. counters to ControlPort. Only called by the scheduler. More... | |
| bool | is_pc_rpc_set () const |
| Checks if this block is already exporting perf. counters to ControlPort. More... | |
| void | no_pc_rpc () |
| If the block calls this in its constructor, it's perf. counters will not be exported. More... | |
| void | set_processor_affinity (const std::vector< int > &mask) override |
Set the thread's affinity to processor core n. More... | |
| void | unset_processor_affinity () override |
| Remove processor affinity to a specific core. More... | |
| std::vector< int > | processor_affinity () override |
| Get the current processor affinity. More... | |
| int | active_thread_priority () |
| Get the current thread priority in use. More... | |
| int | thread_priority () |
| Get the current thread priority stored. More... | |
| int | set_thread_priority (int priority) |
| Set the current thread priority. More... | |
| bool | update_rate () const |
| void | system_handler (pmt::pmt_t msg) |
| the system message handler More... | |
| void | set_log_level (const std::string &level) override |
| Set the logger's output level. More... | |
| std::string | log_level () override |
| Get the logger's output level. More... | |
| bool | finished () |
| returns true when execution has completed due to a message connection More... | |
| block_detail_sptr | detail () const |
| void | set_detail (block_detail_sptr detail) |
| void | notify_msg_neighbors () |
| Tell msg neighbors we are finished. More... | |
| void | clear_finished () |
| Make sure we don't think we are finished. More... | |
| std::string | identifier () const |
| Public Member Functions inherited from gr::basic_block | |
| pmt::pmt_t | message_subscribers (pmt::pmt_t port) |
| ~basic_block () override | |
| long | unique_id () const |
| long | symbolic_id () const |
| std::string | name () const |
| std::string | symbol_name () const |
| std::string | identifier () const |
| gr::io_signature::sptr | input_signature () const |
| gr::io_signature::sptr | output_signature () const |
| basic_block_sptr | to_basic_block () |
| bool | alias_set () const |
| std::string | alias () const |
| pmt::pmt_t | alias_pmt () const |
| void | set_block_alias (std::string name) |
| void | message_port_register_in (pmt::pmt_t port_id) |
| void | message_port_register_out (pmt::pmt_t port_id) |
| void | message_port_pub (pmt::pmt_t port_id, pmt::pmt_t msg) |
| void | message_port_sub (pmt::pmt_t port_id, pmt::pmt_t target) |
| void | message_port_unsub (pmt::pmt_t port_id, pmt::pmt_t target) |
| virtual bool | message_port_is_hier (pmt::pmt_t port_id) |
| virtual bool | message_port_is_hier_in (pmt::pmt_t port_id) |
| virtual bool | message_port_is_hier_out (pmt::pmt_t port_id) |
| pmt::pmt_t | message_ports_in () |
| Get input message port names. More... | |
| pmt::pmt_t | message_ports_out () |
| Get output message port names. More... | |
| void | _post (pmt::pmt_t which_port, pmt::pmt_t msg) |
| bool | empty_p (pmt::pmt_t which_port) |
| is the queue empty? More... | |
| bool | empty_p () |
| bool | empty_handled_p (pmt::pmt_t which_port) |
| are all msg ports with handlers empty? More... | |
| bool | empty_handled_p () |
| size_t | nmsgs (pmt::pmt_t which_port) |
| How many messages in the queue? More... | |
| void | insert_tail (pmt::pmt_t which_port, pmt::pmt_t msg) |
| pmt::pmt_t | delete_head_nowait (pmt::pmt_t which_port) |
| msg_queue_t::iterator | get_iterator (pmt::pmt_t which_port) |
| void | erase_msg (pmt::pmt_t which_port, msg_queue_t::iterator it) |
| virtual bool | has_msg_port (pmt::pmt_t which_port) |
| const msg_queue_map_t & | get_msg_map (void) const |
| virtual void | setup_rpc () |
| Set up the RPC registered variables. More... | |
| bool | is_rpc_set () |
| Ask if this block has been registered to the RPC. More... | |
| void | rpc_set () |
| When the block is registered with the RPC, set this. More... | |
| virtual bool | check_topology (int ninputs, int noutputs) |
| Confirm that ninputs and noutputs is an acceptable combination. More... | |
| template<typename T > | |
| void | set_msg_handler (pmt::pmt_t which_port, T msg_handler) |
| Set the callback that is fired when messages are available. More... | |
| virtual void | set_processor_affinity (const std::vector< int > &mask)=0 |
| virtual void | unset_processor_affinity ()=0 |
| virtual std::vector< int > | processor_affinity ()=0 |
| virtual void | set_log_level (const std::string &level)=0 |
| virtual std::string | log_level ()=0 |
| Public Member Functions inherited from gr::msg_accepter | |
| msg_accepter () | |
| ~msg_accepter () override | |
| void | post (pmt::pmt_t which_port, pmt::pmt_t msg) override |
send msg to msg_accepter on port which_port More... | |
| Public Member Functions inherited from gr::messages::msg_accepter | |
| Protected Types inherited from gr::basic_block | |
| enum | vcolor { WHITE , GREY , BLACK } |
| Protected Member Functions inherited from gr::block | |
| block (void) | |
| block (const std::string &name, gr::io_signature::sptr input_signature, gr::io_signature::sptr output_signature) | |
| void | set_fixed_rate (bool fixed_rate) |
| void | add_item_tag (unsigned int which_output, uint64_t abs_offset, const pmt::pmt_t &key, const pmt::pmt_t &value, const pmt::pmt_t &srcid=pmt::PMT_F) |
| Adds a new tag onto the given output buffer. More... | |
| void | add_item_tag (unsigned int which_output, const tag_t &tag) |
| Adds a new tag onto the given output buffer. More... | |
| void | remove_item_tag (unsigned int which_input, uint64_t abs_offset, const pmt::pmt_t &key, const pmt::pmt_t &value, const pmt::pmt_t &srcid=pmt::PMT_F) |
| DEPRECATED. Will be removed in 3.8. More... | |
| void | remove_item_tag (unsigned int which_input, const tag_t &tag) |
| DEPRECATED. Will be removed in 3.8. More... | |
| void | get_tags_in_range (std::vector< tag_t > &v, unsigned int which_input, uint64_t abs_start, uint64_t abs_end) |
| Given a [start,end), returns a vector of all tags in the range. More... | |
| void | get_tags_in_range (std::vector< tag_t > &v, unsigned int which_input, uint64_t abs_start, uint64_t abs_end, const pmt::pmt_t &key) |
| Given a [start,end), returns a vector of all tags in the range with a given key. More... | |
| void | get_tags_in_window (std::vector< tag_t > &v, unsigned int which_input, uint64_t rel_start, uint64_t rel_end) |
| Gets all tags within the relative window of the current call to work. More... | |
| void | get_tags_in_window (std::vector< tag_t > &v, unsigned int which_input, uint64_t rel_start, uint64_t rel_end, const pmt::pmt_t &key) |
Operates like gr::block::get_tags_in_window with the ability to only return tags with the specified key. More... | |
| void | enable_update_rate (bool en) |
| buffer_sptr | allocate_buffer (size_t port, int downstream_max_nitems, uint64_t downstream_lcm_nitems, uint32_t downstream_max_out_mult) |
| Allocate a buffer for the given output port of this block. Note that the downstream max number of items must be passed in to this function for consideration. More... | |
| Protected Member Functions inherited from gr::basic_block | |
| basic_block (void) | |
| basic_block (const std::string &name, gr::io_signature::sptr input_signature, gr::io_signature::sptr output_signature) | |
| Protected constructor prevents instantiation by non-derived classes. More... | |
| void | set_input_signature (gr::io_signature::sptr iosig) |
| may only be called during constructor More... | |
| void | set_output_signature (gr::io_signature::sptr iosig) |
| may only be called during constructor More... | |
| void | set_color (vcolor color) |
| Allow the flowgraph to set for sorting and partitioning. More... | |
| vcolor | color () const |
| virtual bool | has_msg_handler (pmt::pmt_t which_port) |
Tests if there is a handler attached to port which_port. More... | |
| virtual void | dispatch_msg (pmt::pmt_t which_port, pmt::pmt_t msg) |
| template<typename Derived > | |
| std::shared_ptr< Derived > | shared_from_base () |
| This is meant to be called by derived classes (e.g. block) to get a shared pointer internally. This is needed because std::enable_shared_from_this doesn't seem to work with derived classes in an inheritance hierarchy. More... | |
| Protected Attributes inherited from gr::block | |
| std::vector< long > | d_max_output_buffer |
| std::vector< long > | d_min_output_buffer |
| unsigned int | d_blkd_input_timer_value = 250 |
| gr::thread::mutex | d_setlock |
| const pmt::pmt_t | d_pmt_done |
| const pmt::pmt_t | d_system_port |
| Protected Attributes inherited from gr::basic_block | |
| std::string | d_name |
| gr::io_signature::sptr | d_input_signature |
| gr::io_signature::sptr | d_output_signature |
| long | d_unique_id |
| long | d_symbolic_id |
| std::string | d_symbol_name |
| std::string | d_symbol_alias |
| vcolor | d_color |
| bool | d_rpc_set |
| gr::logger_ptr | d_logger |
| gr::logger_ptr | d_debug_logger |
| Default logger. More... | |
| msg_queue_map_t | msg_queue |
| Verbose logger. More... | |
| std::vector< rpcbasic_sptr > | d_rpc_vars |
| pmt::pmt_t | d_message_subscribers |
Header/Payload demuxer (HPD).
This block is designed to demultiplex packets from a bursty transmission. The typical application for this block is the case when you are receiving packets with yet-to-determine length. This block will pass the header section to other blocks for demodulation. Using the information from the demodulated header, it will then output the payload. The beginning of the header needs to be identified by a trigger signal (see below).
Input 0 takes a continuous transmission of samples (items). Input 1 is an optional input for the trigger signal (mark beginning of packets). In this case, a non-zero value on input 1 identifies the beginning of a packet. Otherwise, a tag with the key specified in trigger_tag_key is used as a trigger (its value is irrelevant).
Until a trigger signal is detected, all samples are dropped onto the floor. Once a trigger is detected, a total of header_len items are copied to output 0. The block then stalls until it receives a message on the message port header_data. The message must be a PMT dictionary; all key/value pairs are copied as tags to the first item of the payload (which is assumed to be the first item after the header). The value corresponding to the key specified in length_tag_key is read and taken as the payload length. The payload, together with the header data as tags, is then copied to output 1.
If the header demodulation fails, the header must send a PMT with value pmt::PMT_F. The state gets reset and the header is ignored.
To generically and transparently handle different kinds of modulations, including OFDM, this block distinguises between symbols and items.
Items are what are consumed at the input. Anything that uses complex samples will therefore use an itemsize of sizeof(gr_complex). Symbols are a way of grouping items. In OFDM, we usually don't care about individual samples, but we do care about full OFDM symbols, so we set items_per_symbol to the IFFT / FFT length of the OFDM modulator / demodulator. For single-carrier modulations, this value can be set to the number of samples per symbol, to handle data in number of symbols, or to 1 to handle data in number of samples. If specified, guard_interval items are discarded before every symbol. This is useful for demuxing bursts of OFDM signals.
On the output, we can deal with symbols directly by setting output_symbols to true. In that case, the output item size is the symbol size.
Example: OFDM with 48 sub-carriers, using a length-64 IFFT on the modulator, and a cyclic-prefix length of 16 samples. In this case, itemsize is sizeof(gr_complex), because we're receiving complex samples. One OFDM symbol has 64 samples, hence items_per_symbol is set to 64, and guard_interval to 16. The header length is specified in number of OFDM symbols. Because we want to deal with full OFDM symbols, we set output_symbols to true.
Example: PSK-modulated signals, with 4 samples per symbol. Again, itemsize is sizeof(gr_complex) because we're still dealing with complex samples. items_per_symbol is 4, because one item is one sample. guard_interval must be set to 0. The header length is given in number of PSK symbols.
By default, the assumption is made that the trigger arrives on exactly the sample that the header starts. These triggers typically come from timing synchronization algorithms which may be suboptimal, and have a known timing uncertainty (e.g., we know the trigger might be a sample too early or too late).
The demuxer has an option for this case, the header_padding. If this value is non-zero, it specifies the number of items that are prepended and appended to the header before copying it to the header output.
Example: Say our synchronization algorithm can be off by up to two samples, and the header length is 20 samples. So we set header_len to 20, and header_padding to 2. Now assume a trigger arrives on sample index 100. We copy a total of 24 samples to the header port, starting at sample index 98.
The payload is not padded. Let's say the header demod reports a payload length of 100. In the previous examples, we would copy 100 samples to the payload port, starting at sample index 120 (this means the padded samples appended to the header are copied to both ports!). However, the header demodulator has the option to specify a payload offset, which cannot exceed the padding value. To do this, include a key payload_offset in the message sent back to the HPD. A negative value means the payload starts earlier than otherwise. (If you wanted to always pad the payload, you could set payload_offset to -header_padding and increase the reported length of the payload).
Because the padding is specified in number of items, and not symbols, this value can only be multiples of the number of items per symbol if either output_symbols is true, or a guard interval is specified (or both). Note that in practice, it is rare that both a guard interval is specified and a padding value is required. The difference between the padding value and a guard interval is that a guard interval is part of the signal, and comes with every symbol, whereas the header padding is added to only the header, and is not by design.
Any tags on the input stream are copied to the corresponding output if they're on an item that is propagated. Note that a tag on the header items is copied to the header stream; that means the header-parsing block must handle these tags if they should go on the payload. A special case are tags on items that make up the guard interval. These are copied to the first item of the following symbol. If a tag is situated very close to the end of the payload, it might be unclear if it belongs to this packet or the following. In this case, it is possible that the tag might be propagated twice.
Tags outside of packets are generally discarded. If there are tags that carry important information that must not be list, there are two additional mechanisms to preserve the tags:
special_tags. This block will then always save the most current value of 'rx_freq' and add it to the beginning of every packet. | typedef std::shared_ptr<header_payload_demux> gr::digital::header_payload_demux::sptr |
|
static |
| header_len | Number of symbols per header |
| items_per_symbol | Number of items per symbol |
| guard_interval | Number of items between two consecutive symbols |
| length_tag_key | Key of the frame length tag |
| trigger_tag_key | Key of the trigger tag |
| output_symbols | Output symbols (true) or items (false)? |
| itemsize | Item size (bytes per item) |
| timing_tag_key | The name of the tag with timing information, usually 'rx_time' or empty (this means timing info is discarded) |
| samp_rate | Sampling rate at the input. Necessary to calculate the rx time of packets. |
| special_tags | A vector of strings denoting tags which shall be preserved (see Tag Handling) |
| header_padding | A number of items that is appended and prepended to the header. |
1.9.4