Re: A bit of Floating Point help needed

Am Montag, 25. Juli 2022, 21:55:25 CEST schrieb ruud_at_baltissen.org:
> Hallo allemaal,
>
>
> For a very long time I'm working on three software projects between
> other things:
> - My own OS meant to run on 8088 PC compatibles. My targets: C= PC10
> series. Main hurdle at this moment: directories.
> - my own bootable BASIC, same targets. Shares a lot of routines with the
> OS.
> - My own Pascal, written in Turbo Pascal, which outputs macros. My
> assembler should turn the macros into binaries for the various target
> machines. For the moment only the PC and the C64.
>
> The last two projects have one thing in common: they need Floating Point
> routines for the mathematical part. So far I only found the sources of
> the original Microsoft's GW-BASIC and the so called URC library. In
> short: the code of both is very hard to understand. And I'm not the only
> one with this opinion.
>
> For my Pascal I can use the FP routines used by the C64 of course. Saves
> me a lot of work. OK, "only" 40 bits but that is good enough for me. If
> I understand yhings better, I always can extend the number of bits. The
> idea rose to translate the 6502 code of the C64 into 8088 code. But I
> need some ways to check if things work OK. One idea was to run a small
> BASIC program and to see what happens with the Floating Point registers
> FAC1 and FAC2. I used a simple program:
> 10 I1=1
> 20 I2=2
> 30 i3=I1*I2
> 40 print content of the various FP registers starting from $61
>
> The problem: what ever I do with I1 and I2, the printed values stay the
> same. What I need to know first is if my conversion from a string/number
> to FP is OK. If that is OK, I can fill FAC1 and FAC2 with my own values
> and SYS the various FP routines and check the resulting value.
>
> And I have no good idea yet how to trigger the StringToFAC1 routine at
> $BCF3: the wellknow CHRGET routine is the base of it but what should I
> do to start things up?
>
> Any help is welcome. Many thanks in advance!

perhaps this helps? https://github.com/mrdudz/cc65-floatlib

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