Subject:
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Re: pass by refrence or value?
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Sun, 25 Mar 2001 12:42:42 GMT
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Viewed:
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1425 times
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Some basic facts about C semantics:
As already stated, globals MUST be volatile if they are accessed by more
than one thread, otherwise reads and writes can be out of sync.
What are the types of the variables involved? Scalar values like integers
are always passed by value, i.e. a new copy in the called function. The
same goes for structures, but NOT for arrays.
The use of "memcpy" indicates that the object being passed in large, and
thus I suspect an array. Arrays are always passed as a pointer, since
copying them is considered too expensive to do automatically.
If you want an array that is passed by value, wrap it inside a struct.
/jakob
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Message is in Reply To:
 | | Re: pass by refrence or value?
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| Did you care to declare your global variable as volatile? this (normaly) prevent the compiler to optimize memory access and force it to read the actual value of the variable each time it need it ( instead of localy storing it in a register wich will (...) (24 years ago, 18-Jan-01, to lugnet.robotics.rcx.legos)
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