Quote:
Originally Posted by mcgeezer
Hi All,
I've been looking into the Bit Field 68020 instructions that are available on the A1200 and have been playing with them.
As of yet I haven't really come across many use cases for them over and above what normal AND/OR/NOT/NEG/EOR instructions would do.
It seems they just allow for finer grained control of the normal byte/word/longword sizes but apart from that do they offer anything else?
The BFFFO instruction looks interesting for finding the Most Significant bit set... I could probably use that somewhere but nothing a couple of normal instructions wouldn't solve for me.
Are the BF instructions particularly fast?
Ta,
Geezer
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Heya Geezer, check the Ocean Loader v2 source for an interesting use case.
I've also used it for quarter pixel scroll bit distribution and in a sine scroll
And sure in various 020+ code i've written. I like those instructions.
Yes, all can be done with the usual, but really useful to gain registers and easy of mind.
Even faster in almost all cases (if used appropriately).