3.asm

一些学习汇编语言的代码

PORT_A   EQU  208H
PORT_B   EQU  209H
PORT_C   EQU  20AH
PORT_CW  EQU  20BH

TRUE     EQU  0FFH
FALSE    EQU  0

DISP_BITN EQU  00111000B
DISP_BITM EQU  00000111B

EXIT_KEY EQU  11111111B   ; K8

DATA SEGMENT
SEG7CODE   DB 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,98H
           DB 88H,83H,0C6H,0A1H,86H,8EH
DISP_BIT   DB 0
N          DB ?
M          DB ?
EXIT_FLAG  DB 0

DATA ENDS

CODE SEGMENT
        ASSUME CS:CODE,DS:DATA
START:  MOV AX,DATA
        MOV DS,AX
        MOV DX,PORT_CW
        MOV AL,89H
        OUT DX,AL
NEXT:   CALL KEYINPUT
        MOV AL,N
        MOV DISP_BIT,DISP_BITN
        CALL DISP
        CALL DELAY
        MOV AL,M
        MOV DISP_BIT,DISP_BITM
        CALL DISP
        CALL DELAY
        CMP EXIT_FLAG,TRUE
        JNZ NEXT
        MOV AH,4CH
        INT 21H

KEYINPUT:
               MOV DX,PORT_C
               IN AL,DX
               MOV N,0
               MOV M,8
               MOV CX,8
KEYINPUT_NEXT: SHL AL,1
               ADC N,0
               LOOP KEYINPUT_NEXT
               MOV AL,M
               SUB AL,N
               MOV M,AL
               CMP AL,0
               JNZ KEYINPUT_EXIT
                   MOV EXIT_FLAG,TRUE
KEYINPUT_EXIT: RET

; INPUT: AL
DISP:
        LEA BX,SEG7CODE
        AND AL,0FH
        XLAT
        MOV DX,PORT_B
        OUT DX,AL
        MOV AL,DISP_BIT
        MOV DX,PORT_A
        OUT DX,AL
        RET

DELAY:
        PUSH BX
        PUSH CX
        MOV BX,5000
NEXT2:  MOV CX,0FFFFH
NEXT1:  DEC CX
        JNZ NEXT1
        DEC BX
        JNZ NEXT2
        POP CX
        POP BX
        RET

CODE    ENDS
        END START