Overview

Common Instruction Sets

  • Intel x86 processors

  • ARM

    • Applicable to most newer macs and smartphones/tablets.

  • RISC-V

    • Stands for Reduced Instruction Set Computers - Five

    • Common in Embedded Systems and Microcontrollers

Registers (x86_64)

We have 16 general purpose registers that can each hold 64 bits. The label/name for each one indicates how many of those 64 bits we are referring to.

Base Label All 64-bits Lower 32-bits Lower 16-bits Lower 8-bits Description
A RAX EAX AX AL Accumulator (results)
B RBX EBX BX BL Base (address calculations)
C RCX ECX CX CL Counter (loops)
D RDX EDX DX DL Data (math and I/O)
SI RSI ESI SI SIL Source Index
DI RDI EDI DI DIL Destination Index
BP RBP EBP BP BPL Base Pointer
SP RSP ESP SP SPL Stack Pointer
8 R8 R8D R8W R8B General use
… … … … … …
15 R15 R15D R15W R15B General use

Note that for registers A, B, C, and D, the upper 8 bits of the lower 16 bits can be addressed with AH, BH, CH, and DH.

Registers and Common Roles/Conventions

Register(s) Convention
RAX Return value (or accumulator)
RBX Callee-saved register
RCX 4th argument
RDX 3rd argument
RSI 2nd argument
RDI 1st argument
RSP Stack pointer
RBP Base pointer
R8–R9 5th and 6th arguments
R10–R11 Temporary values (caller-saved)
R12–R15 Callee-saved / general use

Standards for this Class

  • RAX is for results

  • RCX, RDX, RSI, RDI, R8, and R9 are for arguments

  • RBP and RSP shouldn’t be touched unless you know what you’re doing.

Install NASM

To install nasm on your vm, run the following two commands.

sudo apt update
sudo apt install nasm

To confirm the install, run the following command.

nasm -v

Check for Linker

To double check that you have the gcc linker installed, run the following command.

ld --version

If for some reason it is not installed, run the following command to install the entire GNU compiler collection and related tools.

sudo apt update
sudo apt install build-essential