Snippets for yer computer needs


Intel Syntax

mnemonic  destination, source

Arithmetic expressions in square brackets

AT&T Syntax

mnemonic  source, destination

The mnemonic has a suffix indicating the size

suffix desc
q qword
l lword
w word
b byte

VASM assembler


# Build assembler for 68000 with motorola syntax
make CPU=m68k SYNTAX=mot


# Valid output formats
nasm -hf
# don't preprocess (assemble only)
nasm -a ...
# assemble to raw binary
nasm -f bin
# assemble to ELF64 (Linux)
nasm -f elf64 example.asm
# assemble to macho64 (macOS)
nasm -f macho64 example.asm
; Set to 32-bit


Dealing with null bytes

Since strcpy stops at a null byte, you’ll need to adjust your instructions to avoid it

; moving zero into a register
; null byte
mov eax, 0
; no null byte
xor eax, eax