ARM SEL instruction and GE flags (parallel arithmetic)

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ippasm

Joined: 24 Oct 2013
Posts: 13

ippasm 25 Oct 2013, 10:59

Hi all,

I have been reading a lot about ARM assembly and I am interested on the GE flags associated with the SEL instruction. Specifically, I am interested in finding how can I manually get and set the values on those flags.

I would be very happy if someone could help...

Best regards,

ippasm

25 Oct 2013, 10:59

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20430
Location: In your JS exploiting you and your system

revolution 25 Oct 2013, 12:18

You can use MSR to set and/or clear any flags directly.

25 Oct 2013, 12:18

ippasm

Joined: 24 Oct 2013
Posts: 13

ippasm 25 Oct 2013, 13:07

Hi Revolution,

Could you please give a code example of how to set/get those flags? I have not been capabe of finding where they are placed on the msr and I have not found any code example....

Best regards,

ippasm

P.S. - Revolution, do you think there is a chance that fasmarm will ever be available as a dl (see http://board.flatassembler.net/topic.php?t=6239)?

25 Oct 2013, 13:07

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20430
Location: In your JS exploiting you and your system

revolution 25 Oct 2013, 14:00

GE3:GE0 are in the CPSR bits 19:16. You can write to them like this:

Code:

msr cpsr_s,0xf shl 16 ;set all of the GE flags to 1

25 Oct 2013, 14:00

ippasm

Joined: 24 Oct 2013
Posts: 13

ippasm 25 Oct 2013, 16:24

Many thanks!

Coud you please answer the question regarding if fasmarm will ever be made available as a dll?

_________________
Best regards,

ippasm

25 Oct 2013, 16:24

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20430
Location: In your JS exploiting you and your system

revolution 25 Oct 2013, 21:59

Perhaps. The use case is quite small so it is not high on my priority list ATM.

25 Oct 2013, 21:59

ippasm

Joined: 24 Oct 2013
Posts: 13

ippasm 28 Oct 2013, 10:14

Ok! Thanks anyway!

_________________
Best regards,

ippasm

28 Oct 2013, 10:14

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