Semaphores in DSP/BIOS

Randy Yates · 2010-05-28T14:24:10+00:00

OK, this may be a stupid question but I'm going to go ahead and askit. I seem to be missing something very basic in the use of semaphores.The SEM module in DSP/BIOS maintains a non-negative count of the numberof times it has been "posted". Then when a pend occurs, the processeither a) blocks if count = 0, or b) decrements count and resumes.I have one task T1 that must run to completion before other tasks (T2,..., TN) run. It *seems* this would be a good use of a semaphore;create a semaphore SEM_T1, then have each task T2, ..., TN pend onSEM_T1. Then when T1 completes, it posts to SEM_T1.However, this won't work with DSP/BIOS semaphores. What will happen isthat the first task that pended, say, T2, will get unblocked when T1completes, but since there was only one pend by T1, none of the otherT3-TN will unblock.How would you solve this problem in DSP/BIOS?-- Randy Yates % "Watching all the days go by... Digital Signal Labs % Who are you and who am I?"mailto:// % 'Mission (A World Record)', % *A New World Record*, ELO

May 28, 2010 41 Replies

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Tim Wescott 16 years ago

MT! (that's the spelling) from US Software used to do that -- their binary semaphore (they called it an "event") had a 'regular' pend, and a 'check', where you could pend but not clear.

I think it's Nucleus now, but I disremember.

Tim Wescott Control system and signal processing consulting www.wescottdesign.com

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Not Really Me 16 years ago

Wow, this may be stating the obvious, but there sure don't seem to be many DSP/BIOS users on here.

Scott Validated Software Lafayette, CO __________ Information from ESET NOD32 Antivirus, version of virus signature database 5169 (20100603) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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