Register Usage

John Farmer
Tue Apr 28 22:06:00 GMT 2009

Hi Ian thanks for the reply,

I had a good look through the ARM-THUMB Procedure Call Standard and it sort
of suggests that R7 could be used as a frame pointer. Looked through the GCC
docs and found the -fabi option but it appears to apply to C++ code.

I am still wondering what makes the decision to use R7 as the frame pointer.
If its used because of an ABI standard for the ARM Cortex-M3 CPU how is it
specified to GCC? Also if this is the case is there a standard that I could
look through? I have looked on the ARM web site but not found it yet.

Regards John

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