Final review Lesson 7 macros and intro to subroutines

How to start a macro?

.macro

How to end a macro?

.endm

where are macros in code?

above .data section

How to name macros?

.macro thisISMyMacroName

How to pass registewrs and varibles to macros?

.macro thisISMyMacroName src_reg1, canBeAnything, src_reg2

How to acces the varible you passed into the macro?

EX: CMP \src_reg1,

\canBeAnything

why use macros?

Increase reusability

No need to use branching

Updating registers

Having modular codes

How to call a subroutine?

BL subroutineName

translation:

LR=PC+4

PC=label

How to exit a subroutine?

BX LR

translation:

PC=LR

What are registers r0-r3 used for?

arguments and return value, these are where you want your final answers when exiting a subroutine. also the registers you want to use when passing in information to a subroutine.

What are registers r4-r11 used for?

General purpose registers, you can use for anything in a subroutine but its proper etiquette to push and pop these when exiting a subroutine.

what is register r12 used for?

(IP) intra procedure call register

what is register r13 used for?

(SP) Stack pointer

what is register r14 used for?

(LR) link register, like bread crumbs leaving a trail in your code to go back to

what is register r15 used for?

(PC) program counter

How many bits can each r0-r3 register hold when passing in arguments?

each 32-bits, combined 128-bits