Re: [cc65] calling conventions

From: Groepaz <groepaz1gmx.net>
Date: 2009-03-07 12:33:15
On Samstag 07 März 2009, Ullrich von Bassewitz wrote:
> Good morning!
>
> On Sat, Mar 07, 2009 at 01:38:54AM +0100, Groepaz wrote:
> > i have a dumb question... a function written in assembler (which is
> > called from C) that returns an unsigned char, does it have to set the Y
> > register to 0 before returning? so far i assumed yes, is that true? and
> > does that requirement change if the function is declared __fastcall__ ?
>
> If you're talking about the X register, then yes. The compiler assumes that
> the default promotions are already done, so when returning chars, the X
> register has to be set. This does not depend on the __fastcall__ property
> of the function.
>
> If you're really talking about the Y register then no, it does not have to
> be set on return.

uh yes, i ment X (the primary register highbyte) ofcourse... it has been 
late :) thanks for confirming :)

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Received on Sat Mar 7 12:33:21 2009

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