liang@cvl.UUCP (Eli Liang) (02/06/85)
I'm posting this for a friend. He has posed a very interesting question
and my own machine with a 68K is down because of power problems and I
can't try it out.
Does anyone here *KNOW* what the 68K will do when confronted with the
following instruction?
move.w (A4)+,(A4)+
It seems that this could do any of a number of things, depending on the
actual microcode for the move instruction. Please, no speculations.
There is enough of that sort of thing on the net :-)
-eli
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Eli Liang ---
University of Maryland Computer Vision Lab, (301) 454-4526
ARPA: liang@cvl, eli@mit-mc, eli@mit-prep CSNET: liang@cvl
UUCP: {seismo,allegra,brl-bmd}!umcp-cs!cvl!liangguy@rlgvax.UUCP (Guy Harris) (02/07/85)
> Does anyone here *KNOW* what the 68K will do when confronted with the > following instruction? > > move.w (A4)+,(A4)+ For those of you with insatiable curiosity, it behaves in the "most straightforward" way - it picks up whatever A4 points to, bumps A4 by 2, drops the picked-up value at the location where A4 now points, and bumps A4 again. (Tested on a real live 68000) Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy
shelby@rtech.ARPA (Shelby Thornton) (02/15/85)
> Does anyone here *KNOW* what the 68K will do when confronted with the > following instruction? > > move.w (A4)+,(A4)+ > This instruction will take the contents of the address in A4 and duplicate it at the contents of A4+1. For example, if A4 points to the string "abcd", after this instruction is executed, the string will be "abab". To make sure I was correct I wrote a simple test case and it did exactly this. Shelby Thornton Relational Technology