.MODEL SMALL
.STACK 100H
.DATA
PROMPT_1 DB 'Enter a Binary number (max 16-bit) : $'
PROMPT_2 DB 0DH,0AH,'The equivalent Decimal number is : $'
ILLEGAL DB 0DH,0AH,'Illegal character. Try again : $'
.CODE
MAIN PROC
MOV AX, @DATA ; initialize DS
MOV DS, AX
LEA DX, PROMPT_1 ; load and display the string PROMPT_1
MOV AH, 9
INT 21H
CALL BINARY_INPUT ; call the procedure BINARY_INPUT
LEA DX, PROMPT_2 ; load and display the string PROMPT_2
MOV AH, 9
INT 21H
MOV AX, BX ; set AX=BX
CALL OUTDEC ; call the procedure OUTDEC
MOV AH, 4CH ; return control to DOS
INT 21H
MAIN ENDP
;**************************************************************************;
;**************************************************************************;
;------------------------- Procedure Definitions ------------------------;
;**************************************************************************;
;**************************************************************************;
;**************************************************************************;
;---------------------------- BINARY_INPUT ------------------------------;
;**************************************************************************;
BINARY_INPUT PROC
; this procedure will read a number in binary form
; input : none
; output : store binary number in BX
; uses : MAIN
JMP @AGAIN ; jump to label @AGAIN
@ERROR: ; jump label
LEA DX, ILLEGAL ; load and display the string ILLEGAL
MOV AH, 9
INT 21H
@AGAIN: ; jump label
MOV CX, 16 ; initialize loop counter
XOR BX, BX ; clear BX
MOV AH, 1 ; set input function
@INPUT: ; loop label
INT 21H ; read a digit
CMP AL, 0DH ; compare input and CR
JE @END ; jump to label @END if input is CR
CMP AL, 30H ; compare AL with 0
JL @ERROR ; jump to label @ERROR if AL<0
CMP AL, 31H ; compare AL with 1
JG @ERROR ; jump to label @ERROR if AL>1
AND AL, 0FH ; convert ascii to decimal code
SHL BX, 1 ; shift BX by 1 position towards left
OR BL, AL ; place the input decimal digit in BL
LOOP @INPUT ; jump to label @INPUT if CX!=0
@END: ; jump label
RET ; return control to the calling procedure
BINARY_INPUT ENDP
;**************************************************************************;
;------------------------------- OUTDEC ---------------------------------;
;**************************************************************************;
OUTDEC PROC
; this procedure will display a decimal number
; input : AX
; output : none
; uses : MAIN
PUSH BX ; push BX onto the STACK
PUSH CX ; push CX onto the STACK
PUSH DX ; push DX onto the STACK
CMP AX, 0 ; compare AX with 0
JGE @START ; jump to label @START if AX>=0
PUSH AX ; push AX onto the STACK
MOV AH, 2 ; set output function
MOV DL, "-" ; set DL='-'
INT 21H ; print the character
POP AX ; pop a value from STACK into AX
NEG AX ; take 2's complement of AX
@START: ; jump label
XOR CX, CX ; clear CX
MOV BX, 10 ; set BX=10
@REPEAT: ; loop label
XOR DX, DX ; clear DX
DIV BX ; divide AX by BX
PUSH DX ; push DX onto the STACK
INC CX ; increment CX
OR AX, AX ; take OR of Ax with AX
JNE @REPEAT ; jump to label @REPEAT if ZF=0
MOV AH, 2 ; set output function
@DISPLAY: ; loop label
POP DX ; pop a value from STACK to DX
OR DL, 30H ; convert decimal to ascii code
INT 21H ; print a character
LOOP @DISPLAY ; jump to label @DISPLAY if CX!=0
POP DX ; pop a value from STACK into DX
POP CX ; pop a value from STACK into CX
POP BX ; pop a value from STACK into BX
RET ; return control to the calling procedure
OUTDEC ENDP
;**************************************************************************;
;--------------------------------------------------------------------------;
;**************************************************************************;
END MAIN
;**************************************************************************;
;**************************************************************************;
;------------------------------ THE END ---------------------------------;
;**************************************************************************;
;**************************************************************************;