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From: bobc@tikal.UUCP (Bob Campbell)
Newsgroups: comp.sys.mac
Subject: Re: Small bug in MacMETH toolbox-interface
Message-ID: <560@tikal.UUCP>
Date: Tue, 18-Nov-86 17:48:53 EST
Article-I.D.: tikal.560
Posted: Tue Nov 18 17:48:53 1986
Date-Received: Thu, 20-Nov-86 08:23:29 EST
References: <446@daimi.UUCP>
Reply-To: bobc@tikal.UUCP (Bob Campbell)
Organization: Teltone Corp., Kirkland, WA
Lines: 70

In article <446@daimi.UUCP> jnp@daimi.UUCP (J|rgen N|rgaard) writes:
>Small bug in MacMETH 2.0 Toolbox interface:
>the result parameter is a "VAR IconItem:Byte", due to modulas
>way of handling BYTEs this is wrong. Pascal and modula use
>exactly the opposite BYTEs of a WORD when accessing just one
>BYTE.
....
>One solution could be: (in interface module of course)
>	VAR dirty : RECORD
>                      b1,b2:BYTE
>	            END;
>..........
>	GetIconItem(parameter1,parameter2, dirty.b1);
PROCEDURE GetItemIcon(theMenu:MenuHandle;item:INTEGER;VAR icon:CHAR);

Either the definition is wrong (and I believe that it is correct as
per Inside Mac but I have not checked), or there are serious problems.
Neither the Mac nor MacMETH should assume that when a BYTE size
variable is passed that the address of the real byte is the address
passed + 1, this just does not make since to me.  I do know that value
parameters are passed differently as MacMETH uses MOVE.B xxx,-(A7) and
the normal Mac routines used MOVE.W xxx,-(A7).

The MacMETH code is something like follows:

PROCEDURE Example(VAR b:BYTE);
BEGIN
	b := 0C;
END Example;
VAR	x:BYTE;
BEGIN
	Example(x);
END ...

example
	LINK	A6,#0		; Link A6
	MOVEA.L	8(A6),A3	; Get the address of b
	MOVE.B	#0,(A3)		; Store 0 into b
	UNLK	A6		; Unlink
	MOVEA.L	(A7)+,A3	; I believe that it uses A3 most of the time
	LEA	4(A7),A7	; Pop Parameter
	JMP	(A3)		; Return

    	PEA	x,-(A7)		; Push Address of x
   	BSR	Example		; Call Example

OR for a trap routine
PROCEDURE Examp(VAR b:BYTE); CODE 0A9FFH;
VAR	x:BYTE;
BEGIN
	Examp(x);
END ...

    	PEA	x,-(A7)
   	DC.W	A9FF

At this point you have passed the address of the exact byte that you
want it to work with.  If it messes with something else then there are
big problems, I don't beleive that either MacMETH or the MacIntosh ROMs
would do this (unless there is a bug).

I would like to here what the final resolution of this problem is,
(and may do some experments at home to find out).

Bob Campbell
Teltone Corporation		18520 - 66th AVE NE
P.O. Box 657			Seattle, WA 98155
Kirkland, WA 98033

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