ARM VERSION 1.2 - Manual (Page 316)

Directives Reference
7-34 Copyright © 2000, 2001 ARM Limited. All rights reserved. ARM DUI 0068B
7.5.1 FRAME ADDRESS
The FRAME ADDRESS directive describes how to calculate the canonical frame address for
following instructions. You can only use it in functions with FUNCTION and ENDFUNC or
PROC and ENDP directives.
Syntax
FRAME ADDRESS reg[,offset]
where:
reg is the register on which the canonical frame address is to be based. This
is sp unless the function uses a separate frame pointer.
offset is the offset of the canonical frame address from reg . If offset is zero, you
can omit it.
Usage
Use FRAME ADDRESS if your code alters which register the canonical frame address is
based on, or if it alters the offset of the canonical frame address from the register. You
must use
FRAME ADDRESS immediately after the instruction which changes the calculation
of the canonical frame address.
Note
If your code uses a single instruction to save registers and alter the stack pointer, you
can use
FRAME PUSH instead of using both FRAME ADDRESS and FRAME SAVE (see FRAME
PUSH on page 7-36).
If your code uses a single instruction to load registers and alter the stack pointer, you
can use
FRAME POP instead of using both FRAME ADDRESS and FRAME RESTORE (see FRAME
POP on page 7-35).
Example
_fn FUNCTION ; CFA (Canonical Frame Address) is value
; of sp on entry to function
STMFD sp!, {r4,fp,ip,lr,pc}
FRAME PUSH {r4,fp,ip,lr,pc}
SUB sp,sp,#4 ; CFA offset now changed
FRAME ADDRESS sp,24 ; - so we correct it
ADD fp,sp,#20
FRAME ADDRESS fp,4 ; New base register
; code using fp to base call-frame on, instead of sp