Article-I.D.: cbmvax.988
Posted: Thu Nov 13 12:51:32 1986
Date-Received: Thu, 13-Nov-86 21:48:51 EST
References: <156@uwslh.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 59

 >  
 >  	The problem: passing 'char' variables by value to procedures.  It took
 >  me a year to discover this, and after I changed how I was passing chars, I
 >  haven't had problems since.  I have talked with several people VERY familiar
 >  with C, and this is what we have come up with.  Apparently, when C (in 
 >  general)> passes a char variable, it is expanded to the size of an int, 
 >  pushed on the stack, the procedure is called, the variable (now size int) 
 >  is popped off, and it is 'decomposed' down to a char size again.  

Just a point here - while I wouldn't be surprised if the method you
describe is actually what C-Power does, being thet you're running on a 
6510, that has nothing to do which C language in general.  This is a
compiler implementation detail, and will change from machine to machine.
On the Amiga, for instance, the first several parameters in a function
call are passed in machine registers, not on the stack.  

 >  However, C-power seems to leave out the 'decomposition' step...
 >  Chris Lishka                   /lishka@uwslh.uucp
 >  Wisconsin State Lab of Hygiene -lishka%uwslh.uucp@rsch.wisc.edu
 >                                 \{seismo, harvard,topaz,...}!uwvax!uwslh!lishka

I don't actually own C64 C-Power, though I played with a friend's copy
about a year ago for a weekend.  I didn't run across this bug, but I
encountered another compiler error.  It seems if I were to use either:

#define BYTE char;

or 

typedef char BYTE;

and then create a function like:

BYTE Wombat(x,y,x)
BYTE x,y,z;
{...}

The compiler would choke, claiming some sort of syntax error.  I think this
was fixed in later versions, and the best way to find out about any of
the compiler upgrades or any other information is to call the C-Power BBS,
the number should be in the front of your manual.  The BBS is in Canada, 
and they (as of last I heard) only support Punter (often pronounced
Punt-Her) protocol.  I've been considering the C-128 version of the
C-Power compiler; its a really good compiler, very fast, and the editor
with error checking is really nice.  Then again, I have all these Amiga
around to write C code on...

-- 
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Dave Haynie	{caip,ihnp4,allegra,seismo}!cbmvax!daveh

	"Laws to supress tend to strengthen what they would prohibit.
	 This is the fine point on which all the legal professions of
	 history have based their job security."
						-Bene Gesserit Coda

These opinions are my own, though for a small fee they may be yours too.

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