> On 2019-10-14, at 21:46, Spiro Trikaliotis <ml-cbmhackers_at_trikaliotis.net> wrote: > > Hello Patryk, > > * On Mon, Oct 14, 2019 at 07:05:38PM +0200 silverdr_at_wfmh.org.pl wrote: >> I need to do some FP calculations (one division, several >> multiplications) and wanted to use available BASIC routines. There's >> for example the GIVAYF routine that converts from 16 bit ints into FAC >> float format. Things work fine as long as I have "signed" ints on the >> input. What I need is "unsigned" so that I could use the whole 16 bit >> range. Suggestions appreciated. > > tested many, many years ago, and I think it actually worked (addresses > of a C64): > > LDY #low > LDA #high > STY $63 > STA $62 > LDX #$90 > SEC > JSR $BC49 Ha! That looks good. Not a single JSR but probably as close to it as it gets. And Carry means "+" here. Makes sense. Thanks, Spiro. > Taken From: > Lothar English, Das Maschinensprache Buch für Fortgeschrittene zum > Commodore 64, Data Becker 1984, p. 23. > There are also examples for converting 1, 2, 3 or 4 byte values signed > or unsigned to FP. I have a copy of this book somewhere, and now, when you wrote about it, I recall that big part of it was actually about FP calculations, which I didn't need back then. -- SD!Received on 2020-05-29 23:08:56
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