[libopcodes] Switching manually between print_insn_arm and print_insn_thumb(16|32)

[libopcodes] Switching manually between print_insn_arm and print_insn_thumb(16|32)

[Emmanuel Fleury]

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Hello,

I am writing a small disassembler for ARM based on libopcodes. For now,
I managed to get the full ARM mode to be operational (32 bits
instructions).

But, once I get the disassembler_ftype (I simplified the code):

  abfd->arch_info = bfd_scan_arch ("arm");
  this->disassembler_fn = disassembler(abfd);

How can I switch to thumb mode on demand ?

I would like to get access to print_insn_thumb(16|32) when needed.


I also have a second question which is somehow a bit similar. I would
like to be able to decide what endianness is selected in the abdf
structure. I tried to access directly to the field and set it:

  (abfd)->xvec->byteorder = BFD_ENDIAN_BIG;

But, the xvec created by new_bfd() seems to be read-only. Is there a way
to work around and be able to modify endianness on-the-fly ?

Regards
-- 
Emmanuel Fleury

Computer Science is no more about computers than astronomy is
about telescopes.
  -- Edsger Dijkstra


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Re: [libopcodes] Switching manually between print_insn_arm and print_insn_thumb(16|32)

[Dr. David Alan Gilbert]

* Emmanuel Fleury (fleury@labri.fr) wrote:
> Hello,
> 
> I am writing a small disassembler for ARM based on libopcodes. For now,
> I managed to get the full ARM mode to be operational (32 bits
> instructions).
> 
> But, once I get the disassembler_ftype (I simplified the code):
> 
>   abfd->arch_info = bfd_scan_arch ("arm");
>   this->disassembler_fn = disassembler(abfd);
> 
> How can I switch to thumb mode on demand ?
> 
> I would like to get access to print_insn_thumb(16|32) when needed.
> 
> 
> I also have a second question which is somehow a bit similar. I would
> like to be able to decide what endianness is selected in the abdf
> structure. I tried to access directly to the field and set it:
> 
>   (abfd)->xvec->byteorder = BFD_ENDIAN_BIG;
> 
> But, the xvec created by new_bfd() seems to be read-only. Is there a way
> to work around and be able to modify endianness on-the-fly ?

I used the following to do it:

https://github.com/penguin42/pocketdisassembler/blob/master/jni/binutilsglue.c#L46

there's also an option you can pass to force thumb mode. I think it's 'force-thumb'

Dave

> 
> Regards
> -- 
> Emmanuel Fleury
> 
> Computer Science is no more about computers than astronomy is
> about telescopes.
>   -- Edsger Dijkstra
> 


-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\ gro.gilbert @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

Re: [libopcodes] Switching manually between print_insn_arm and print_insn_thumb(16|32)

[Emmanuel Fleury]

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Hello,

On 08/18/2014 11:38 AM, Dr. David Alan Gilbert wrote:
> 
> I used the following to do it:
> 
> https://github.com/penguin42/pocketdisassembler/blob/master/jni/binutilsglue.c#L46
> 
> there's also an option you can pass to force thumb mode. I think it's 'force-thumb'

Thanks for your answer.

Indeed, the 'force-thumb' is far enough to switch between the two modes.

And, the code you pointed on GitHub gave me the right direction for
coding what I want (I think that my original problem was indeed coming
from my code and not the binutils code).

Thanks again !

Regards
-- 
Emmanuel Fleury

What if everything is an illusion and nothing exists?
In that case, I definitely overpaid for my carpet.
  -- Woody Allen


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