Re: Memory Access Question

[walsh@stdc01.UUCP (Mike Walsh)]

>>Others have commented that you should write in assembler to 
>>do low-level memory accesses, but keep in mind that you don't
>>really need to leave Ada to use assembly language:  just use
>>machine-code insertions!   It's for this kind of application
>>that Ada provides machine_code.  Now if your compiler does not 
>>support machine code then you're out of luck, but a number of 
>>good Ada compilers do.
>>-- 
>>-- Mike Murphy
>>-- UUCP: sun!decwrl!mips!murphy
>>-- AT&T: (408) 991-0438

 In my experience, writing machine code insertions is not as trivial as
 this posting makes it out to be.  The project I worked on was and ARMY
 contract and they wanted everything done in Ada.  We were using the
 Softech Ada86 Compiler and an Intel 80186.  Softech provided the Machine
 Code Package, but it was incomplete or erroneous.  Plus anyone writing
 machine code insertions had better be better than just average assembly
 language programmer.  IMHO it is better to write the routine in Assembly,
 and pass an Address to the routine from the Ada caller, or just invoke
 an Assembly Language routine from Ada, since if the code needs to be 
 protable, it is likely that the architecture of the machine that the
 porting is being done on is different from the original machine.  Since
 the architecture is most likely different, the memory scheme is probably
 different.  I also feel that a good Assembly Language Routine that is
 well documented is much more maintainable than a peice of code written
 in machine code insertions.  BTW, machine code insertions are machine
 dependent anyway.


...Mike

Mike Walsh, Electrical Engineer
Star Technologies 
Graphicon Products Division
P.O. Box 13951
Reserach Triangle Park, NC 27709
(919) 361-3800

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