LAB7NEW

; ex3.asm

    .MODEL SMALL
    .STACK 100h
    .DATA
NumInsertion    DB 'Please enter number: ','$'
perfectstr      DB 13,10,'Perfect number!','$'
Not_perfectstr  DB 13,10,'Not perfect number!','$'
flag            DB 0
number          DD 0
ten             DD 10
two             DD 2
maxDer          DD ?
DerSum          DD 0

     .CODE
.386
;procedure 1 "getPNum":
getPNum  PROC NEAR
    ;PUSHing register values in order to save them
     PUSH EAX
     PUSH EDX

    ;set print option and print Character Insertion prompt
     MOV AH,9
     MOV DX,OFFSET NumInsertion
     INT 21h
     XOR CX, CX
InsertionLoop:
     MOV EAX, 0
    ;set get character option and put it into temp
     MOV AH,1
     INT 21h
    ;compare the char inserted to ENTER, if equal end the loop
     MOV AH, 0
     CMP AL, 13
     JE EndLoop
     SUB AL, '0'
     ADD EAX, number
     MUL ten
     MOV number, EAX
     JMP InsertionLoop

EndLoop:
     MOV EDX, 0
     MOV EAX, number
     DIV ten
     MOV number, EAX

    ;POPing stacked values back to registers
     POP EDX
     POP EAX
    ;Ending procedure
     RET
     getPNum  ENDP


;procedure 2 "PNum":
PNum PROC NEAR
     PUSH EAX
     PUSH EDX
     PUSH ECX
    ;initiate ECX as a counter
     MOV ECX, 0
    ;We can decrease the number of iterations by 2 if we set the maximun derative possible to number/2, there is not a number that divides by more than his half.
     MOV EAX, number
     MOV EDX, 0
     DIV two
     MOV maxDer, EAX

LoopDerative:
     INC ECX
     MOV EAX, number
     MOV EDX, 0
     ;check the remain of the devition number/ECX
     DIV ECX
     CMP EDX, 0
     JNE dontCountDer
     ADD DerSum, ECX
    ;compare ECX and the max derative we had set in order to finish the loop
dontCountDer:
     CMP ECX, maxDer
     JNE LoopDerative

     MOV EAX, DerSum
     CMP EAX, number
     JNE EndProc
     MOV flag, 1
EndProc:
     POP ECX
     POP EDX
     POP EAX
     RET
     PNum ENDP


ProgStart:
     MOV AX,@DATA
     MOV DS,AX
;Call procedure "getPNum" in order to receive the input from the user
     MOV DX, OFFSET number
     CALL getPNum
;Call procedure "PNum" in order to check if the number is perfect
     CALL PNum
     CMP flag, 0
     JE DispNotPerfect
DispPerfect:        ;set print option and print perfectstr
     MOV AH,9
     MOV DX,OFFSET perfectstr
     INT 21h
     JMP EndProgram

DispNotPerfect:     ;set print option and print Not_perfectstr
     MOV AH,9
     MOV DX,OFFSET Not_perfectstr
     INT 21h

EndProgram:         ; Set terminate option and return to DOS
     MOV AH,4Ch
     INT 21h
    END ProgStart