;A4-4.asm
;用減奇法開平方運算

STACK1  SEGMENT STACK
         DW 256 DUP(?)
STACK1  ENDS

DDATA	SEGMENT
MES1	DB	'The square root of $'
MES2	DB	' is:$'
NUMB	DW	0040H
DDATA	ENDS

CODE    SEGMENT 
	ASSUME CS: CODE,DS:DDATA
	
START: MOV	AX,DDATA
	   MOV	DS,AX

	   MOV	DX,OFFSET MES1
	   MOV	AH,09H
	   INT	21H
	   MOV	SI,OFFSET NUMB
	   MOV 	AX,[SI]
	   CALL	SHWORD
	   MOV	DX,OFFSET MES2
	   MOV	AH,09H
	   INT	21H
	
	   MOV	AX,[SI]
	   MOV 	CL,00H
	   MOV 	DX,0001H
A1:	   SUB 	AX,DX
	   JB 	A2	
	   INC 	CL
	   ADD 	DX,02H
	   JMP 	A1
A2:	   MOV	BL,CL
	   CALL	SHOW

	   MOV	AX,4C00H
	   INT	21H
	
SHWORD	PROC	NEAR
	   MOV	BL,AH
	   CALL	SHOW
	   MOV	BL,AL
	   CALL	SHOW
	   RET	
	   ENDP
		
SHOW	PROC	NEAR
	   PUSH	AX
	   PUSH	DX
	   MOV	AL,BL
	   AND	AL,0F0H			;取高4位
	   SHR	AL,4
	   CMP	AL,0AH			;是否是A以上的數
	   JB	C2		
	   ADD	AL,07H		
C2:	   ADD	AL,30H		
	   MOV	DL,AL			;show character 
	   MOV	AH,02H
	   INT	21H
       MOV	AL,BL
	   AND	AL,0FH			;取低4位
	   CMP	AL,0AH
	   JB	C3
	   ADD 	AL,07H
C3:	   ADD	AL,30H
	   MOV	DL,AL			;show character 
	   MOV	AH,02H
	   INT	21H
	   POP	DX
	   POP	AX
	   RET
	   ENDP	
CODE  ENDS
       END START