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Thumb mode, Thumb2 MRS insturction issue.

Note: This was originally posted on 28th July 2011 at http://forums.arm.com

Dear All

I have find a strange behavior on cortexA9/R4,

My mode data code as below

0x0 0x8100F3EF MRS R1,CPSR (current CPSR value is 0x1F3)

However when I execute the line, the value in R1 is 0x1D3, Isn't it should be 0x1F3?

Is it a chip bug? or there is some other reason?

If anyone knows the answer, please let me know.

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Martin Weidmann over 12 years ago

Note: This was originally posted on 28th July 2011 at http://forums.arm.com

Bit 5 is the T bit (ARM or Thumb state). The value you're getting back implies you are in fact in ARM state. How do you know what the value should be? Are you using a debugger?
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Martin Weidmann over 12 years ago

Note: This was originally posted on 28th July 2011 at http://forums.arm.com

Bit 5 is the T bit (ARM or Thumb state). The value you're getting back implies you are in fact in ARM state. How do you know what the value should be? Are you using a debugger?
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