; Jade Yu Cheng
; ICS 312
; Assignment 7 Exercise 1
; April 24, 2009
; This program takes one command-line argument, which should be a floating
; point number. The program then calls a function called compute_exp that
; computes the exponential function.
%include "asm_io.inc"
%define x dword [ebp + 8] ; define x to be the argument
segment .bss
counter resq 1 ; a buffer space
segment .text
global compute_exp
compute_exp:
push ebp ; setup
mov ebp, esp ; setup
push ebx ; setup reserve ebx
fld1 ; st0 is the previous x^n/n!
fld1 ; st1 is the previous summation
mov ebx, 0 ; loop counter
add_loop:
cmp ebx, 40 ; loop 40 times
jz add_loop_end
inc ebx ; increment the loop counter
fxch st1 ; first work on updating x^n/n
fmul dword x ; x^(n-1)/(n-1) * x = x^n/(n-1)
mov [counter], ebx
fidiv dword [counter] ; (x^n/(n-1))/n = x^n/n
fxch st1 ; then work on updating the summation
fadd st1 ; add the new item x^n/n
jmp add_loop
add_loop_end:
pop ebx ; clean up
mov esp, ebp ; clean up
pop ebp ; clean up
ret ; clean up
