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Entry  Thu Nov 10 04:41:24 2016, Abhishek Rajput, Break Statements in DRS4 Binary to ROOT Macro 
    Reply  Thu Nov 10 09:56:04 2016, Stefan Ritt, Break Statements in DRS4 Binary to ROOT Macro 
       Reply  Thu Nov 10 19:24:52 2016, Abhishek Rajput, Break Statements in DRS4 Binary to ROOT Macro 
          Reply  Thu Nov 10 22:07:40 2016, Stefan Ritt, Break Statements in DRS4 Binary to ROOT Macro 
Message ID: 557     Entry time: Thu Nov 10 04:41:24 2016     Reply to this: 558
Author: Abhishek Rajput 
Subject: Break Statements in DRS4 Binary to ROOT Macro 

Hello,

I recently modified the binary to ROOT convertor written by Stefan (https://midas.psi.ch/elogs/DRS4+Forum/361) so it can decode data taken with any channel or set of channels  on the DRS4. In the process of testing this modifed version for data taken on all 4 channels, I encountered problems with decoding some of the event data. More specifically, upon hitting a certain event in some channel, the histograms for that channel would no longer be filled and the histograms for subsequent channels would not be filled with any event at all. 

After considerable bug hunting, I discovered the source of this problem was due to the break statement in the following code extract from the ROOT to binary macro:

 for (n=0 ; n<5 ; n++) {
      // read event header
      i = fread(&eh, sizeof(eh), 1, f);
      if (i < 1)
         break;

For some events apparently, the event header fails to be read properly (fread line returns 0 in this case). Moreover, when I used the feof and ferror functions on a particular file I was testing, the feof function returned a value of 1.

So my questions deal with two scenarios.

Firstly, in the event of an fread error, is a break statement is necessary? Is it not possible to skip the voltage data for those events whose event header fails to be read properly? Or is it the case that when some "corrupted" event header is encountered, all waveform data subsequent to that event is likewise corrupted? If the former is the case, is it advisable to replace the break condition with an fseek line that advances the position indicator of the stream by an additional 2052*n_channels + 32 bytes (in accordance with the binary file specifications of page 25 on the DRS4 manual) so that the next set of voltage data can be read? 

Secondly, in the case of an end of file error, does there exist any possible solution? Or is such an error an indication of a faulty drs4 channel or corrupted binary file? 

Any help with the aforementioned issues would be greatly appreciated.

 

Abhishek

 

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