Here's what you can do to add a "complicated" constant stored elsewhere, in hand-crafted assembler: add_something: ; function starts here (argument

Here's what you can do to add a "complicated" constant stored elsewhere, in hand-crafted assembler: add_something: ; function starts here (argument r0 == some number) ldr r1, __tmp ; get complicated constant, store in r1 add r0, r0, r1 ; do the addition r0 = r0 + r1 bx lr ; == return result (in r0) __tmp: .word 0x12345678 ; store complicated constant here You can play with your compiler, if you call gcc as "gcc -Os -S -o- file.c" if will spit out generated assembler code (-S) on stdout "-o-" for the c-code in file.c. (but then, gcc prefers to have 4 "compact" adds, instead of loading a constant...) $ cat dummy.c int add_random_number(int a) { return a + 0x12345678; /* guaranteed to be random */ } $ arm-none-eabi-gcc -S -o- -Os dummy.c (...) add_random_number: @ Function supports interworking. @ args = 0, pretend = 0, frame = 0 @ frame_needed = 0, uses_anonymous_args = 0 @ link register save eliminated. add r0, r0, #301989888 add r0, r0, #3424256 add r0, r0, #5696 add r0, r0, #56 bx lr