putstr macro  aa
    lea   dx,aa
    mov   ah,09
    int   21h
       endm
putchar macro  rr
    mov   dl,rr
    mov   ah,02
    int   21h
       endm

.MODEL SMALL
.STACK
.DATA
    msg1  db 'This is a test$'
    msg2  db 'a tet$'
    msg3  db ' the second string is a substring of the first string$'
    msg4  db 'first  string --> $'
    msg5  db 'second string --> $'
    msg6  db ' the second string is not a substring of the first string$'
    odoa  db 0dh,0ah,'$'
    len   dw ?
.CODE
    MOV   AX,@DATA
    MOV   DS,AX
    MOV   ES,AX
;
    putstr msg4
    putstr msg1
    putstr odoa
    putstr msg5
    putstr msg2
    putstr odoa
;
    xor   si,si
    xor   cx,cx
comp:
    cmp   msg2[si],'$'
    je    getcount
    inc   cx
    inc   si
    jmp   comp
;
getcount:
    mov   len,cx
;
    mov   al,msg2    ; 1st character of msg2
    lea   di,msg1
    cld
    mov   cx,14
    repne scasb      ; search 1st character
    je    compstr
    putstr msg6      ; no such character
    putstr odoa
    jmp   dos
;
compstr:
;
    cld
    mov   cx,len
    dec   di         ; in msg1
    lea   si,msg2
    repe  cmpsb      ; compare 2 strings
    jz    printeq
    putstr msg6      ; no such substring
    putstr odoa
    jmp   dos
;
printeq:
    putstr msg3      ; print equal
    putstr odoa
;
dos:
    mov   ah,4ch
    int   21h
END