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PostPosted: Mon Oct 29, 2012 1:24 pm 
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Joined: Sun Oct 28, 2012 8:38 pm
Posts: 2
Hello,

I'm having problem with compiling statements like:
Code:
test ds.w 1
 move.w (test, d0.w * 8), d1
 pea (test, d0.w * 4);


I tried
Code:
 move.w test(d0.w * 8)

and so on, but without success.
I have 68k code disassembled by IdaPro and there it is like that so
it's legal in 68k assembly.

I can mimic it with this code, but it's not efficient:
Code:
lea test, a0
lsl.w  #3, d0
move.w (a0, d0), d1

Am I doing something wrong, or is this addressing mode unsupported?

best regards, Filip


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PostPosted: Mon Oct 29, 2012 1:50 pm 
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Joined: Thu Dec 16, 2004 6:42 pm
Posts: 1118
The 68000 does not support scaled index registers
Code:
d0.w * 8
That addressing mode is supported by 68020 and higher CPUs.

_________________
Prof. Kelly


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PostPosted: Mon Oct 29, 2012 2:07 pm 
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Joined: Sun Oct 28, 2012 8:38 pm
Posts: 2
profkelly wrote:
The 68000 does not support scaled index registers
Code:
d0.w * 8
That addressing mode is supported by 68020 and higher CPUs.


Mea culpa! Yes, that's true. I spent too much of time programming 68030 and above processors :) Well as I need it very much (I'm modifying some embedded device firmware) but I know opcode, so I can replace it with macro and generate 68000 code for simulation and real instruction for the result.

Thank you!


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PostPosted: Wed Oct 31, 2012 1:08 am 
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Joined: Mon Jul 26, 2010 11:43 pm
Posts: 198
Location: Aurora, IL
For 680x0 dev work IDE68K might be a better route, it also supports 68881/2 instructions.

http://home.kpn.nl/pj.fondse/ide68k/


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