openDAQ
Open data acquisition platform
TailReaderPtr Class Reference

A reader that only ever reads the last N samples, subsequent calls may result in overlapping data. More...

+ Inheritance diagram for TailReaderPtr:
+ Collaboration diagram for TailReaderPtr:

Detailed Description

A reader that only ever reads the last N samples, subsequent calls may result in overlapping data.

Public Member Functions

daq::TailReaderStatusPtr read (void *values, daq::SizeT *count) const
 Copies at maximum the next count unread samples to the values buffer. The amount actually read is returned through the count parameter. More...
 
daq::TailReaderStatusPtr readWithDomain (void *values, void *domain, daq::SizeT *count) const
 Copies at maximum the next count unread samples and clock-stamps to the values and stamps buffers. The amount actually read is returned through the count parameter. More...
 
daq::SizeT getHistorySize () const
 The maximum amount of samples in history to keep. More...
 
- Public Member Functions inherited from GenericSampleReaderPtr< ITailReader >
daq::SampleType getValueReadType () const
 Gets the sample-type the signal value samples will be converted to when read or SampleType::Invalid if read-type has not been determined yet. More...
 
daq::SampleType getDomainReadType () const
 Gets the sample-type the signal domain samples will be converted to when read or SampleType::Invalid if read-type has not been determined yet. More...
 
void setValueTransformFunction (const daq::FunctionPtr &transform) const
 Sets the transform function that will be called with the read value-data and currently valid Signal-Descriptor giving the user the chance add a custom post-processing step. The function should have a signature compatible with: More...
 
void setDomainTransformFunction (const daq::FunctionPtr &transform) const
 Sets the transform function that will be called with the read domain-data and currently valid Signal-Descriptor giving the user the chance add a custom post-processing step. The function should have a signature compatible with: More...
 
daq::ReadMode getReadMode () const
 Gets the reader's read mode which determines if the reader will also scale the read data or not. More...
 
- Public Member Functions inherited from GenericReaderPtr< InterfaceType >
daq::SizeT getAvailableCount () const
 Gets the number of segments available to read. More...
 
void setOnDataAvailable (const daq::ProcedurePtr &callback) const
 Sets the specified callback function to be called when there is available data in the reader. Pass nullptr to unset the callback. The callback should take no arguments. More...
 
daq::Bool getEmpty () const
 Checks if there is data to read. More...