[Coco] Nitros9 C and maths lib

[Jeff Teunissen]

Just wondering, what format are your floating point numbers in? OS-9 C
(like almost every other C at the time) uses PDP-11/VAX format for its
floating point numbers. It's slightly different from the little-endian IEEE
754 stuff we usually see today, but with a little massaging it's compatible.

On Mon, Oct 21, 2019, 11:39 AM Walter <zambotti at iinet.net.au> wrote:

> James
>
> Sorry missed your reply way back in July.
>
> Not sure what you mean about state but it currently is not multi tasking
> safe.
>
> It uses a number of ports to set up pointers to the source and destination
> values and another port to trigger the required function.
>
> As this requires several bytes written the execution could be interrupted
> at any time and this would cause issues if more than one FPU task was
> running at a time.
>
> I suppose I could create a wrapper around the calls that turned off
> interrupts for the duration of the FPU call.
>
> Walter
>
> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of James Jones
> Sent: Thursday, 4 July 2019 11:31 AM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] Nitros9 C and maths lib
>
> Virtual FPU device? Is that documented? How much state information does it
> keep around?
>
> On Mon, Jun 10, 2019 at 2:24 AM Walter Zambotti <zambotti at iinet.net.au>
> wrote:
>
> > I have converted my raytrace program to use the virtual FPU device in
> OVCC.
> >
> >
> >
> > It improves performance by around 50 times.
> >
> >
> >
> > As I was no longer using any function (pow,sin,cos) from the standard
> > mlib.l
> > library I removed it from the link and it links without any issue however
> > the floating point maths computations are all zero!!!
> >
> >
> >
> > This seems strange.  Why would I need to include a library that is no
> > longer
> > referenced?
> >
> >
> >
> > So if I use either of these two compile commands:
> >
> >
> >
> > cc -A raytrace.c -l=/dd/lib/mlib.l -m=8k
> >
> >
> >
> > or
> >
> >
> >
> > cc -A raytrace.c -m=8k
> >
> >
> >
> > Both compile and link without error however only the former produces
> > correct
> > output.
> >
> >
> >
> > Walter
> >
> >
> > --
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> >
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