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Author Topic: Looking for assembly syntax slightly different from mototrolla ?  (Read 5420 times)

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Offline EinsteinTopic starter

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Re: Looking for assembly syntax slightly different from mototrolla ?
« Reply #14 from previous page: October 18, 2017, 10:27:26 AM »
Quote from: Thomas Richter;831892
Huh, why not? Of course it does, in the same sense the 68020 onwards supports a move with indirection without an address register. The same address mode can - of course - be used for JMP or JSR. The 68K series is really very orthogonal. Since there is a move.l (a0),d0, there is of course also a jsr (a0), and since there is a move.l (abs.l),d0 (for the 68020 on) there is also an jsr (abs.l). No problem - this is extended indirect with index and supressed base register.


Hi!

I mean plain 68000 (not 68020, I have never examined/played with anything 680x0 above 68000). I'm not talking about indirect calls/jumps through aN, but through memory locations. I don't remember below instruction to be possible/supported on 68000, is it ?

Code: [Select]
bsr (funcptr)

'funcptr' being label for some (relative) address.
I have spoken !
 

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Re: Looking for assembly syntax slightly different from mototrolla ?
« Reply #15 on: October 18, 2017, 11:59:39 AM »
Quote from: Einstein;831897
I mean plain 68000 (not 68020, I have never examined/played with anything 680x0 above 68000). I'm not talking about indirect calls/jumps through aN, but through memory locations. I don't remember below instruction to be possible/supported on 68000, is it ?
For a simple 68000, you are completely correct. For the 68020, there is the double-indirect mode which allows that if combined with the suppressed base-register and long displacement.

Quote from: Einstein;831897
Code: [Select]
bsr (funcptr)'funcptr' being label for some (relative) address.
Well, indeed, but that's more a restriction of the "branch" family. All "conditional branches" only take byte, word or - with the 68020 - long displacements, but no directions or -calculations as the jmp/jsr family does.
 

Offline EinsteinTopic starter

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Re: Looking for assembly syntax slightly different from mototrolla ?
« Reply #16 on: October 18, 2017, 12:15:01 PM »
@Thomas Richter

Thanks for the clarification.
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