Experimental Physics and
Industrial Control System

Till Straumann <[email protected]> · Tue, 29 Oct 2013 14:38:35 -0700

Looking at devGtr.c's waveform device-support I find the following:

1) Execution of the driver's 'readMemory()' and 'readRawMemory()' operators
   is delegated to a callback task which is kicked off by the ISR.

   These operators pull data from the card to a memory buffer.

2)a) If the waveform has FTVL set to SHORT or LONG then the waveform's BPTR
   is directly passed on to readMemory()/readRawMemory(), i.e., in the
   context of the callback task data are copied from the board directly
   into the waveform record.

 b) If FTVL is set to another data type then readMemory/readRawMemory
   deposit data into an intermediate buffer. During record processing
   (waveform's 'read' devsup entry point) samples are copied and converted
   from the intermediate buffer into the waveform record.

=> Scenario 1+2a is not thread-safe. The callback task does not

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System