ARM VERSION 1.2 - page 316

Directives Reference

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

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