ARM or CODE32
ARM directive instructs the assembler to interpret subsequent instructions as ARM instructions, using either the UAL or the pre-UAL ARM assembly language syntax.
CODE32 is a synonym for
In files that contain code using different instruction sets,
ARM must precede any ARM code.
If necessary, this directive also inserts up to three bytes of padding to align to the next word boundary.
This directive does not assemble to any instructions. It also does not change the state. It only instructs the assembler to assemble ARM instructions, and inserts padding if necessary.
ARM and THUMB directives
This example shows how you can use
directives to switch state and assemble both ARM and Thumb instructions in a single
AREA ToThumb, CODE, READONLY ; Name this block of code ENTRY ; Mark first instruction to execute ARM ; Subsequent instructions are ARM start ADR r0, into_thumb + 1 ; Processor starts in ARM state BX r0 ; Inline switch to Thumb state THUMB ; Subsequent instructions are Thumb into_thumb MOVS r0, #10 ; New-style Thumb instructions