CSC231 FindLargestOfArray.asm

--D. Thiebaut 17:17, 1 December 2010 (UTC)

---

;;; findLargestOfArray.asm
;;; D. Thiebaut
;;; Finds the largest item in an array of N elements
;;; 
;;; compile and link as follows:
;;;
;;;  nasm -f elf -F stabs findLargestOfArray.asm
;;;  gcc -o findLargestOfArray driver.c asm_io.o findLargestOfArray.o
;;; 
%include "asm_io.inc"
        
%assign EXIT        1

        ;; -------------------------
        ;; data segment
        ;; -------------------------
        section .data
msg1    db      "large of array = ",0
array   dd      1, 3, 10, 0, -2, 44, 10
N       equ     ($-array)/4        

        
        ;; -------------------------
        ;; code area
        ;; -------------------------
        section .text
        global  asm_main

;;; ---------------------------------------------------------
;;; main program
;;; ---------------------------------------------------------
asm_main:       

;;; largest = MOSTNEG;
;;; for ( i=0; i<N; i++ ) {
;;;     if ( array[i]>largest )
;;;         largest = array[i];
;;; 
;;; print "largest of array = ", largest

        mov     esi, 0
        mov     ebx, 0x80000000 ; most negative dword
        
for:    cmp     esi, N*4
        jge     done
        
        cmp     ebx, dword[array+esi]
        jg      next
        mov     ebx, dword[array+esi]
next:   add     esi, 4
        jmp     for
done:
        mov     eax, ebx
        call    printMax
        
        ret        

;;; ----------------------------------------------------------
;;; printMax: gets integer in eax and prints it
;;; ----------------------------------------------------------
printMax:      
        push    eax             ; save max in stack
        mov     eax, msg1        
        call    print_string    ; prints " "
        pop     eax             ; get max from stack
        call    print_int       ; print fact(i)
        call    print_nl        ; next line
        ret