scasb.asm

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; This sample shows how
; to use SCASB instruction
; to find a symbol.

#make_COM#

; COM file is loaded at 100h
; prefix:
    ORG 100h

; set forward direction:
    CLD

; set counter to string size:
    MOV CX, 10

; load string address
; into ES:DI
    MOV AX, CS
    MOV ES, AX
    LEA DI, str1

; we will look for the 'C'
; character in string:
    MOV AL, 'C'

    REPNE   SCASB

    JZ  found

not_found:

; "No" - not found!
    MOV AL, 'N'
    MOV AH, 0Eh
    INT 10h

    JMP exit_here
found:

; "Yes" - found!
    MOV AL, 'Y'
    MOV AH, 0Eh
    INT 10h

; DI contains the
; offset of 'C' character:
    DEC DI  

exit_here:
    RET

str1 DB 'AAABBBCDDD'


END