18.8: Example Program, Sum and Average

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This example is a simple assembly language program to calculate the sum and average for a list of floating-point values.

; Floating-Point Example Program
; ***********************************************************

section .data 

; -----
;  Define constants.

NULL            equ 0        ; end of string
TRUE            equ 1
FALSE           equ 0

EXIT_SUCCESS    equ 0        ; Successful operation
SYS_exit        equ 60       ; system call code for terminate

; -----

fltLst          dq  21.34,  6.15,  9.12, 10.05,  7.75
                dq   1.44, 14.50,  3.32, 75.71, 11.87
                dq  17.23, 18.25, 13.65, 24.24,  8.88
length          dd  15
lstSum          dq  0.0
lstAve          dq  0.0

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

; -----
;  Loop to find floating-point sum.
      
    mov ecx, [length]
    mov rbx, fltLst
    mov rsi, 0
    movsd  xmm1, qword [lstSum]
      
sumLp:
    movsd      xmm0, qword [rbx+rsi*8]        ; get fltLst[i]
    addsd      xmm1, xmm0                     ; update sum
    inc        rsi                            ; i++
    loop       sumLp                
    
    movsd      qword [lstSum], xmm1
    
; -----
; Compute average of entire list.

    cvtsi2sd    xmm0, dword [length]
    cvtsd2si    dword [length], xmm0
    divsd       xmm1, xmm0
    movsd       qword [lstAve], xmm1
    
; -----
; Done, terminate program. 

last:
    mov    rax, SYS_exit
    mov    rbx, EXIT_SUCCESS                   ; exit w/success    
    syscall

The debugger can be used to examine the results and verify correct execution of the program.