# Digital\_ofdm\_cyclic\_prefixer::work **URL:** \ **Category:** GNU Radio\ **Created:** [June 29, 2013, 8:37am UTC](https://www.ruby-forum.com/t/digital-ofdm-cyclic-prefixer-work/245689 "2013-06-29T08:37:39Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\ **Post date:** [June 29, 2013, 8:37am UTC](https://www.ruby-forum.com/t/digital-ofdm-cyclic-prefixer-work/245689/1 "2013-06-29T08:37:39Z")
Hi all, please can someone tell me why that work method ( like others in the digital\_odfm\_xx ) does not call consume\_each (n) or consume ( i,n ) ? many thanks, Stefano ---
**Author:** ![stefano](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/aca169/32.png) [@stefano](https://www.ruby-forum.com/u/stefano)\ **Post date:** [June 29, 2013, 10:25am UTC](https://www.ruby-forum.com/t/digital-ofdm-cyclic-prefixer-work/245689/2 "2013-06-29T10:25:08Z")
Hi, it looks like the block inherits from gr\_tagged\_stream\_block which will will call a blocks work function with the exact number of samples for one PDU with a known size in general\_work and will call consume for you afterwards. [http://gnuradio.org/doc/doxygen/classgr\_\_tagged\_\_stream\_\_block.html#ac8934fdb1cb2816f2eed20287314614d](http://gnuradio.org/doc/doxygen/classgr __tagged__ stream__block.html#ac8934fdb1cb2816f2eed20287314614d) Yours Martin Am 29.06.2013 08:15, schrieb Stefano: ---
**Author:** ![stefano](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/aca169/32.png) [@stefano](https://www.ruby-forum.com/u/stefano)\ **Post date:** [June 29, 2013, 7:04pm UTC](https://www.ruby-forum.com/t/digital-ofdm-cyclic-prefixer-work/245689/3 "2013-06-29T19:04:24Z")
On Sat, Jun 29, 2013 at 01:10:31PM +0200, Stefano wrote: > > it looks like the block inherits from gr\_tagged\_stream\_block which > > will will call a blocks work function with the exact number of > > samples for one PDU with a known size in general\_work and will > > call consume for you afterwards. For the record: No work() function should _ever_ call consume, regardless of its type (currently, that would be either gr\_sync\_block, gr\_sync\_decimator, gr\_sync\_interpolator and gr\_tagged\_stream\_block). Only call consume() or consume\_each() from general\_work(). There’s one exception: gr\_tagged\_stream\_blocks may fall back to gr\_block behaviour. The cyclic prefixer you mention is such a case, because it is a modification of an existing block, and provides gr\_block style behaviour for backward compatibility. See: [http://gnuradio.org/doc/doxygen/page\_tagged\_stream\_blocks.html](http://gnuradio.org/doc/doxygen/page_tagged_stream_blocks.html) MB – Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin B. Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT – University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association ---
**Author:** ![stefano](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/aca169/32.png) [@stefano](https://www.ruby-forum.com/u/stefano)\ **Post date:** [June 29, 2013, 1:11pm UTC](https://www.ruby-forum.com/t/digital-ofdm-cyclic-prefixer-work/245689/4 "2013-06-29T13:11:35Z")
Thanks Martin, very helpful; forgotten to take a look at the block type. Stefano Il 29/06/2013 10:24, Martin L. ha scritto: