Move (Load/Store) Instructions

Most of the instructions used in a computer program are instructions that move data. The x86 processor uses variable-length instructions and offers very flexible addressing options.

The Unix syntax of x86 instructions shows data movement from left to right:

#  code for i := 0
   movl   $0,%eax         #  0 -> %eax
   movl   %eax,-32(%rbp)  #  %eax -> i

There are three data formats that we will use:

Instruction	Terminology	Bits	Use For
MOVL	long	32	Integer
MOVQ	quad-word	64	Pointer
MOVSD	signed double	64	Float