어셈블리어

function name(label)

a symbol that represents the address where the function’s code starts

call instruction

Copying the stack pointer into the base pointer at the beginning of a function

%ebp is a constant reference to the stack frame

function parameters

pushes all of the parameters for the function onto the stack in the reverse order

%ebp # fixed indexes from the base pointer

return address

call instruction pushes the address of the next instruction onto the stack

local variables

%ebp # fixed indexes from the base pointer

return value

%eax

calling convention of the C programming language

the standard for Linux platforms

ABI, or Application Binary Interface

.section .data

.section .text

.globl _start

_start:

pushl $3 #push second argument

pushl $2 #push first argument

call power

addl $8, %esp

movl %eax, %ebx # exit code

movl $1, %eax # exit system call

int $0x80

.type power, @function # tells the linker that the symbol power should be treated as a function

power:

pushl %ebp #save old base pointer

movl %esp, %ebp #make stack pointer the base pointer

subl $4, %esp #get room for our local storage

movl 8(%ebp), %ebx #put first argument in %eax

movl 12(%ebp), %ecx #put second argument in %ecx

movl %ebx, -4(%ebp) #store current result

power_loop_start:

cmpl $1, %ecx #if the power is 1, we are done

je end_power

movl -4(%ebp), %eax

imull %ebx, %eax

movl %eax, -4(%ebp)

decl %ecx

jmp power_loop_start

end_power:

movl -4(%ebp), %eax #return value

movl %ebp, %esp #restore the stack pointer

popl %ebp #restore the base pointer

ret