将大写转换为小写程序集TASM

Question

我想在程序集TASM中将大写转换为小写，我编写了以下代码。文本位于stdin，最多100个字符。 它应该输出文本并显示读取的字符数，但是当我尝试从键盘输入时它不起作用：

DATA SEGMENT PARA PUBLIC 'DATA'
SIR DB 100 DUP (?)
newline DB 10,13,'$'
DATA ENDS

CODE SEGMENT PARA PUBLIC 'CODE'
ASSUME CS:CODE, DS:DATA, ES:DATA

; procedura de conversie

fctie PROC FAR
; IF AL<'A'
    cmp     al, 'A'
JB iesire
; IF AL>'Z'
    cmp     al, 'Z'
JA iesire
    ADD     AL, 20H

iesire: RET
fctie ENDP

START PROC FAR

    PUSH    DS
    XOR     AX,AX
    PUSH    AX
    MOV     AX,DATA
    MOV     DS,AX
    MOV     ES,AX


        MOV     BL, 0
        MOV     DI, OFFSET SIR
        cld

    ;citirea unui caracter din sir
    L1:
        MOV     AH, 01H
        INT     21H

    ;vf dc e caracterul space
        CMP     AL, ' '
    JE increment

        CMP     AL, '$'
    JE auxL2

    CALL fctie
    ; ca sa evitam intrarea automata in increment 
    JMP auxL
    increment: INC BL
    auxL:

    ;rescrierea caracterului in lowercase
    ;-instructions equiv to stosb
    ;MOV ES:[DI], AL 
    ;INC DI
    STOSB

    auxL2:
    ;vf. dc e sf. de sir
        CMP     AL, '$' 
    LOOPNE L1

    ; linie noua
        LEA     DX, newline
        MOV     AH, 09H
        INT     21H

    ;afisare 
        mov     DX, offset SIR
        MOV     AH, 09H
        INT     21H

    ; afisare nr de cuvinte
        ADD     BL, 01
        MOV     DL, BL
        MOV     AH, 02H
        ADD     DL, 30h; convertire in string pentru ca nr sa afiseze: 30H e val lui 0 hexa in ASCII
        INT     21H

    ;iesire program
        MOV     AH, 4CH
        INT     21H
    START ENDP
    CODE ENDS
    END START