[A83] Re: Point of making your own lcd_busy?

[A83] Re: Point of making your own lcd_busy?

• To: assembly-83@lists.ticalc.org
• Subject: [A83] Re: Point of making your own lcd_busy?
• From: Gavin Olson <gtolson@comcast.net>
• Date: Sat, 08 Feb 2003 13:50:33 -0500
• In-reply-to: <20030208183337.DBE441801B@mx-1.sollentuna.net>
• Reply-To: assembly-83@lists.ticalc.org

At 07:33 PM 2/8/2003 +0100, you wrote:
> > Van: Patai Gergely <patai_gergely@fastmail.fm>
> >
> > > Use:
> > >
> > >    EX (SP),HL
> > >    EX (SP),HL
> > >
> > This seems to be a very good idea, but you shouldn't forget to disable
> > interrupts (e. g. during the screen to LCD function) if you use it.
>
>Why?
>
>It changes the data _at_ the SP, not SP itself.

Indeed.  Even if an interrupt did go off between the statements, an 
interrupt that wouldn't crash the calc anyway would point SP back where it 
should be after.  So, unless there is an interrupt that messes with 
non-shadow HL, its safe.

• [A83] Re: Point of making your own lcd_busy?
• From: "Patai Gergely" <patai_gergely@fastmail.fm>

• [A83] Re: Point of making your own lcd_busy?
• From: "Henk Poley" <hpoley@dds.nl>

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