Assembly

Notes on x86/x86-64 assembly language, covering both AT&T and Intel syntax.

Directory map

• Assembly Notes — Intel vs AT&T syntax, registers, addressing modes, data directives, instructions, stack mechanics, syscalls, calling conventions, GAS and NASM assembling

Summary

These notes cover x86 assembly from first principles. Topics include the two main syntaxes (Intel and AT&T), all register types (data, index, pointer, control, segment, EFLAGS), register sub-divisions, all addressing modes using the disp(base, index, scale) form, program sections, data directives, the full instruction set with AT&T size suffixes, stack mechanics and the standard prologue/epilogue, Linux int 0x80 syscall interface, GAS and NASM assembler/linker commands, and the cdecl calling convention with caller/callee-saved register table.

Example programs referenced in the notes:

• program1.s / program1.o — basic GAS example
• program2.asm — NASM example
• stack.asm / stack.s / stack.o — stack frame examples