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TITLE   ScanCmdl.asm

        INCLUDE SCREEN.MAC


;========================================================================

CSEG    SEGMENT
        ASSUME CS:CSEG,DS:CSEG
        ORG 100h

start:  jmp begin


errmsg db ' is not a valid parameter!',13,10,'$'

main    PROC NEAR

        xor cx,cx
        mov cl,byte ptr ds:[80h]
        cmp cl,00h
        jz ready        

        mov di,81h

scan:
        mov al,'-'
        repne scasb
        cmp cx,0
        je ready

        call get_parm
        jc Error       
        jmp scan
Error:

        mov dl,al
        mov ah,02h
        int 21h

        cmp bl,' '
        jz err_out
        cmp bl,0dh
        jz err_out
        mov dl,bl
        int 21h

err_out:
        mov ah,09h
        mov dx,OFFSET errmsg
        int 21h

        jmp scan
        
ready:        
        ret
main    ENDP


get_parm PROC NEAR

        mov al,byte ptr[di]
        mov bl,byte ptr[di+1]

        cmp bl,' '
        jz kuk        
        cmp bl,0dh
        jz kuk
        jmp p4

kuk:    
        cmp al,'a'
        jnz p2
        Print 'A parameter chosen.'
        call crlf
        clc
        ret
p2:     cmp al,'b'
        jnz p3
        Print 'B parameter chosen.'
        call crlf
        clc
        ret
p3:     cmp al,'c'
        jnz p4
        Print 'C parameter chosen.'
        call crlf
        clc
        ret
p4:     stc
        ret

get_parm ENDP

crlf    PROC NEAR

        cr_lf
        ret

crlf    ENDP
        
;--------------------------------------------------------------------------

begin:
        call main
        ret                             ; -> back to DOS
 
CSEG    ENDS
END     start
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