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Cathode Strip Chamber (CSC) raw data unpacking and packing using bit field classes

Tumanov, Alex and Wilkinson, Rick (2008) Cathode Strip Chamber (CSC) raw data unpacking and packing using bit field classes. Journal of Physics: Conference Series, 119 (2). Art. No. 022032. ISSN 1742-6596. doi:10.1088/1742-6596/119/2/022032.

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Unprecedented data rates that are expected at the LHC put high demand on the speed of the detector data acquisition system. The CSC subdetector located in the Muon Endcaps of the CMS detector has a data readout system equivalent in size to that of a whole Tevatron detector (60 VME crates in the CSC DAQ equal to the whole D0 DAQ size). As a part of the High Level Trigger, the CSC data unpacking runs online and it needs to be able to cope with high data rates online. Early versions of the unpacking code used bit shifts and masks to unpack binary data. To reduce the unpacking time we decided to switch to bit field based data unpacking. The switch allowed us to gain an order of magnitude in speed. In this paper we explain how bit field data unpacking works and why it is dramatically faster compared to conventional bit shift and mask methods.

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Additional Information:© 2008 IOP Publishing Ltd. Accepted papers received: 23 June 2008. Published online: 31 July 2008.
Issue or Number:2
Record Number:CaltechAUTHORS:20090610-142904617
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14393
Deposited By: Ruth Sustaita
Deposited On:19 Aug 2009 01:20
Last Modified:12 Jul 2022 19:46

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