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???
09/21/06 08:21
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 		 #124754 - overlay
Responding to: ???'s previous message
Russell Bull said:
in high level languages and assembler all variables are effectively 'global' as they all exist in the same memory space. However, it comes down the the 'usage' of the variables. In a high level language, you define the 'visibility' of a variable and the rules of the language enforce this 'visibility'.

In high level languages like C or Pascal it's not only the visibility that makes a variable local. The compiler or linker also overlay the variables with others that are currently out of scope. Most compilers use the stack for this but most 8051 tools use real memory overlaying because the 8051 is not good at accessing things on the stack.

List of 56 messages in thread
TopicAuthorDate
Variables within ISR            01/01/70 00:00      
   static            01/01/70 00:00      
      Static, link            01/01/70 00:00      
   beware            01/01/70 00:00      
      Modular Programming            01/01/70 00:00      
         a rebuttal            01/01/70 00:00      
            A Faq about...            01/01/70 00:00      
            Global variables            01/01/70 00:00      
               "Self Documenting"            01/01/70 00:00      
            Global Variables Compromise Modularity            01/01/70 00:00      
               Module vs Global scope            01/01/70 00:00      
               file static            01/01/70 00:00      
                  RE: file static            01/01/70 00:00      
                     extern does matter            01/01/70 00:00      
                  Undeclared Variables            01/01/70 00:00      
                     to Russ            01/01/70 00:00      
                     try this            01/01/70 00:00      
                        Re: try this            01/01/70 00:00      
               Not Evil            01/01/70 00:00      
               module variables            01/01/70 00:00      
                  yes and no all must be weighed            01/01/70 00:00      
         Hmm            01/01/70 00:00      
            the advantages of not suffering from interruptifob            01/01/70 00:00      
            That is the typical way            01/01/70 00:00      
               yes, absolutely            01/01/70 00:00      
                  Depends on the use            01/01/70 00:00      
                     every rule can (and should) be broken            01/01/70 00:00      
            Fixing Problems vs. Hiding Them            01/01/70 00:00      
               I agree, but many take this as an excuse            01/01/70 00:00      
                  Be Defensive            01/01/70 00:00      
   A Module Example            01/01/70 00:00      
      if we are to give examples            01/01/70 00:00      
         Poor example            01/01/70 00:00      
            not so poor            01/01/70 00:00      
         Reasons to Waste Machine Cycles            01/01/70 00:00      
            it is still 'hidden' and BTW why hide it            01/01/70 00:00      
               I'm Done Preaching            01/01/70 00:00      
                  I hope that as well            01/01/70 00:00      
         to asm programmers..            01/01/70 00:00      
            Poor Logic            01/01/70 00:00      
               what an utterly stupid teacher            01/01/70 00:00      
                  OO            01/01/70 00:00      
                     No            01/01/70 00:00      
                     What OOP tells you            01/01/70 00:00      
                        A long Time ago            01/01/70 00:00      
                  I disagree            01/01/70 00:00      
                     some of the worst 'spaghetti' I have seen            01/01/70 00:00      
               Rules in C            01/01/70 00:00      
                  rules imposed on C            01/01/70 00:00      
                     Language Problems            01/01/70 00:00      
            that is very relevant            01/01/70 00:00      
         what about the library?            01/01/70 00:00      
            OH NO            01/01/70 00:00      
               Experience is the best teacher            01/01/70 00:00      
                  overlay            01/01/70 00:00      
                  to Russell            01/01/70 00:00      

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