Experimental Physics and
Industrial Control System

Eric Norum <[email protected]> · Thu, 03 Jun 2004 15:39:15 -0500

Kate Feng wrote:

2)  A patch is needed in RTEMS for all the
3.14.x/src/libCom/osi/os/RTEMS/epicsThread.c files mostly
because a clock tick is required to support the functionality
of  rtems_task_wait_after().
The patch example for the 3.14.5 :
diff  epicsThread.c epicsThread.c.orig

It's a little easier to see what you are proposing if you use the diff -c or
-u options to provide some context for the changes.

58c58
< static int initialized=0;
---
static int initialized;

I don't see how this makes any difference. If your static variables aren't
getting initialized to 0 there must be something wrong with the board-support
package startup code.

385c385
<         delay = 1;
---
 delay = 0;

I think that the existing behaviour matches the semantics described in the
application developer's guide. Here's the code in question:

============================================================

void

epicsThreadSleep (double seconds)

{

rtems_status_code sc;

rtems_interval delay;

extern double rtemsTicksPerSecond_double;
 if (seconds <= 0.0) {

delay = 0;

}

else {

delay = seconds * rtemsTicksPerSecond_double;

if (delay == 0)

delay++;

}

sc = rtems_task_wake_after (delay);

if(sc != RTEMS_SUCCESSFUL)

errlogPrintf("epicsThreadSleep: %s\n", rtems_status_text (sc));

}

=============================================================

The documentation for epicsThreadSleep says, ".... If delay is <= 0 then a
delay of 0 is requested of the underlying architecture. What happens is
architecture-dependent but often allows other threads of the same priority to
run." This is in fact what happens on RTEMS -- rtems_task_wake_after(0)
causes a "yield to other tasks at the same priority".
--
Eric Norum                                 [email protected]
Advanced Photon Source                     Phone: (630) 252-4793
Argonne National Laboratory

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System