Xtc Library How-Tos

Draft, in work.

Topics

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Generating Xtc

For tutorial purposes, the following streamlined example shows XXX. For an example involving more detectors, formats and algorithms, see xtcdata/xtcdata/app/xtcwriter.cc.

A Notional DAQ Harness

Let's motivate the example. Assume we're developing a an Xtc writer class to output CSPAD data. This class will get plugged in to a (notional) DAQ framework.

# Assume some totally made-up data acquisition callback framework named DAQFramework
# Developers of the psdaq package are welcome to come in and change this toy example
# to match the real DAQ API.

CSPADXtcWriter padwriter()

DAQFramework.registerHandler("configure", padwriter.setup)
DAQFramework.registerHandler("runstart", padwriter.setup)
DAQFramework.registerHandler("readout", padwriter.writeImage)
DAQFramework.registerHandler("runend", padwriter.writeFile)

"setup" Method: Set Up The Names Structure

Register the algorithms and "shape" of the data associated with detector elements to tell the processing pipeline how to process the data.

First some plumbing...
1. Create an XtcData:Dgram as the root container.
Next code sample description.

At some initialization step, for example in response to a DAQ configure signal:

Subclass XtcData::VarDef to build a data structure specific to the detector in question.

"writeImage" Method: Add Readout Data

Parsing Whole Xtc Files

xtcreader.cc and XtcIterator.hh

Use of Xtc Small Data Files

this might be duplicate of what's on top page

Notes for Real-World Code

Xtc Writers in the Wild

(You'll likely need to sub-class from XYZ in order to ABC)

Xtc Readers in the Wild

(You'll likely need to sub-class from XYZ in order to ABC)

Full "Hello Xtc" Code Listing, CSPADXtcWriter Example

CSPADXtcWriter::CSPADXtcWriter()
{

}

void CSPADXtcWriter::setup()
{

}

void CSPADXtcWriter::writeImage()
{


}

void CSPADXtcWriter::writeFile()
{


}

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