3. Program for Test Score Evaluation in Assembly Language using Visual Studio

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Chapter 6

Conditional Processing

Assembly Language Programming Exercise

Problem # 3:

Create a procedure named CalcGrade that receives an integer value between 0 and 100, and returns a single capital letter in the AL register. Preserve all other register values between calls to the procedure. The letter returned by the procedure should be according to the following ranges:

Score Range  Letter Grade
----------------------------------
90 to 100        A
80 to  89         B
70 to  79         C
60 to  69         D
  0 to  59         F

Write a test program that generates 10 random integers between 50 and 100, inclusive. Each time an integer is generated, pass it to the CalcGrade procedure.  You can test your program using a debugger, or if you prefer to use the book’s library, you can display each integer and its corresponding letter grade. (The Irvine32 library is required for this solution program because it uses the RandomRange procedure.)

Solution:

INCLUDE Irvine32.inc

.data
s DWORD 50
e DWORD 100
str1 BYTE "The integer score is: ",0
str2 BYTE "The letter grade is:  ",0

.code
main PROC
    call Clrscr
    mov ecx, 10
    l1:  
        mov eax, s
        mov ebx, e
        dec ebx  
        sub ebx, eax        ;create range from 0 to N
        xchg ebx, eax        ;random works with eax
        call RandomRange    ; generate random int witin range 0 to N
        neg ebx                ;change sign of ebx
        sub eax, ebx        ;sub from eax to define range
        mov edx, offset str1
        call WriteString
        call WriteInt
        call crlf
        call CalcGrade
        call crlf
    loop l1

    call WaitMsg
    exit
main ENDP

CalcGrade PROC
    .IF eax >= 90    ; multiway selection structure to
      mov al,'A'    ; choose the correct grade letter
    .ELSEIF eax >= 80
      mov al,'B'
    .ELSEIF eax >= 70
      mov al,'C'
    .ELSEIF eax >= 60
      mov al,'D'
    .ELSE
      mov al,'F'
    .ENDIF
      
    mov edx,OFFSET str2
    call WriteString
    call WriteChar    ; display grade letter in AL
    call Crlf

    ret
CalcGrade ENDP

END main

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