Re: [MiNT] fpu40/60 instructions

[Xavier Joubert <xavier.joubert@free.fr>]

Hello Mikro,


Selon mikro <mikro@hysteria.sk>:
> does anybody know what is the difference between instructions like fsglmul,
> fsgldiv (68881/2) and fsmul, fsdiv(68040/60) ? The same function, but
> another opcode. Maybe there's a typing error, but you get the idea - the
> 68040/60 has a lot of fs/fd pairs included the instructions above, but the
> fsgl- from 68882 is still here, too.

fsgldiv and fsglmul are less accurate (and faster, I think) than fsdiv and
fsmul, since they truncate datas to single precision _before_ computing
results.

This difference is described in the m68k Programmer's reference manual from
Motorola. This book (and the user's manuals for each member of the m68k family)
is available in PDF format here :
http://www.freescale.com/webapp/sps/library/documentationlist.jsp?rootNodeId=01&nodeId=018rH3YTLC4622&Device=All&DocTypeKey=10Ksfwlk&Results=25

Some books are still available as hardcopy. Not this one, unfortunatly.


Best regards,


Xavier