implementing some 68881 unimplemented instructions on 68040

jotd · 29 December 2020, 16:12

WinUAE does a perfect job emulating 68881/68882 FPU instructions on 68040/68060.

I saw a list of exotic stuff but I'm more interested in fmove.d instructions (decimal data type) and how it is emulated, preferably using valid 68040 floating point instructions.

A job done by stuff like oxypatcher et al, but on the project I'm working on it doesn't work too well (TFX) and anyway I can't use them (whdload context)

my plan would be to track them all by disassembly and patch them for each executable specifically. I think I'll have more luck like that than blindly applying a patch I don't know the contents of.

I retried and it seems that real 68040 (winuae, more compatible, no unsupported) chokes on

FMOVECR #$32,FP0

also on

FCOS.X FP0,FP7

seems normal, the 68060 unsupported instructions are according to the manual

FACOS FLOGN
FASIN FLOGNP1
FATAN FMOVECR
FATANH FSIN
FCOS FSINCOS
FCOSH FSINH
FETOX FTAN
FETOXM1 FTANH
FGETEXP FTENTOX
FGETMAN FTWOTOX
FLOG10 FLOG2

FMOD FREM
FSCALE —
FTRAPcc FDBcc
FScc —

I guess those operations aren't implemented for the 040 too. Anyway I'm also targetting the 68060. Is there open source good implementations of those? using only 68060 FP instructions?

Toni Wilen · 29 December 2020, 16:29

Original Motorola 040/060 emulation library (FPSP) assembly sources are available. Probably easiest to use solution.

Search for motorola fpsp or similar, for example it is included with most open source unixes (linux, netbsd etc)

UAE (and Previous) softfloat missing instruction emulation is based on Motorola FPSP.

jotd · 29 December 2020, 17:52

that's great. I'm not going to create a 100% compliant lib, just the instructions I need.

I didn't think it was available, didn't even bother searching.. big thanks (as always).

29 December 2020, 16:12	#1
jotd This cat is no more Join Date: Dec 2004 Location: FRANCE Age: 52 Posts: 8,303	implementing some 68881 unimplemented instructions on 68040 WinUAE does a perfect job emulating 68881/68882 FPU instructions on 68040/68060. I saw a list of exotic stuff but I'm more interested in fmove.d instructions (decimal data type) and how it is emulated, preferably using valid 68040 floating point instructions. A job done by stuff like oxypatcher et al, but on the project I'm working on it doesn't work too well (TFX) and anyway I can't use them (whdload context) my plan would be to track them all by disassembly and patch them for each executable specifically. I think I'll have more luck like that than blindly applying a patch I don't know the contents of. I retried and it seems that real 68040 (winuae, more compatible, no unsupported) chokes on FMOVECR #$32,FP0 also on FCOS.X FP0,FP7 seems normal, the 68060 unsupported instructions are according to the manual FACOS FLOGN FASIN FLOGNP1 FATAN FMOVECR FATANH FSIN FCOS FSINCOS FCOSH FSINH FETOX FTAN FETOXM1 FTANH FGETEXP FTENTOX FGETMAN FTWOTOX FLOG10 FLOG2 FMOD FREM FSCALE — FTRAPcc FDBcc FScc — I guess those operations aren't implemented for the 040 too. Anyway I'm also targetting the 68060. Is there open source good implementations of those? using only 68060 FP instructions? Last edited by jotd; 29 December 2020 at 16:23.

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29 December 2020, 16:29	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,534	Original Motorola 040/060 emulation library (FPSP) assembly sources are available. Probably easiest to use solution. Search for motorola fpsp or similar, for example it is included with most open source unixes (linux, netbsd etc) UAE (and Previous) softfloat missing instruction emulation is based on Motorola FPSP.

29 December 2020, 17:52	#3
jotd This cat is no more Join Date: Dec 2004 Location: FRANCE Age: 52 Posts: 8,303	that's great. I'm not going to create a 100% compliant lib, just the instructions I need. I didn't think it was available, didn't even bother searching.. big thanks (as always).

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