8.2: Example Program, List Summation

Last updated
Save as PDF

Page ID: 19905

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

The following example program will sum the numbers in a list.

; Simple example to the sum and average for
; a list of numbers.

; *****************************************************
;  Data declarations

section .data 

; -----
;  Define constants

EXIT_SUCCESS equ 0             ; successful operation
SYS_exit equ 60                ; call code for terminate

; -----
; Define Data.

section .data 
    lst     dd     1002, 1004, 1006, 1008, 10010
    len     dd     5
    sum     dd     0

; ******************************************************** 
section .text
global _start
_start:

; -----
;  Summation loop.

    mov     ecx, dword [len]             ; get length value
    mov     rsi, 0                       ; index=0

sumLoop:
    mov     eax, dword [lst+(rsi*4)]     ; get lst[rsi]
    add     dword [sum], eax             ; update sum
    inc     rsi                          ; next item
    loop     sumLoop

; -----
;  Done, terminate program.

last:
    mov     rax, SYS_exit                 ; call code for exit
    mov     rdi, EXIT_SUCCESS             ; exit with success
    syscall

The ()'s within the [ ]'s are not required and added only for clarity. As such, the [lst+ (rsi*4)], is exactly the same as [lst+rsi*4].