;;Term Project Konyk Serhiy
.MODEL SMALL
;.586

EXTRN   GetDec:NEAR
EXTRN   PutDec:NEAR
EXTRN	PutHex:NEAR


INCLUDE	PCMac.INC

.STACK 100h

.DATA
A       DW  	?
Msg1	DB      '		CALCULATOR	     ', 13,10, '$'
Msg2	DB	'Choose an operation, (or # to enter number):    ', '$'
Msg3	DB	'No such op.  (? for help)',13,10,'$'
	
Prompt1 DB      10,13,'Enter a number:   ','$'
		
Helpmsg	DB	10, 13, '#-to enter two numbers'
	DB	10, 13, '$-to display a stack'
	DB	10, 13, '+-to add two numbers'
	DB	10, 13, '--to subtract two numbers'
	DB	10, 13, '/-to divide two numbers'
	DB	10, 13, '*-to multiply two numbers'
	DB	10, 13, '%-to divide with remaider'
	DB	10, 13, 'r-to squareroot thenumber'
	DB	10, 13, 'h-to convert a number to hexidecimal'
	DB	10, 13, '!-factorial'
	DB	10, 13, 'f-recurcive factorial'
	DB	10, 13, '>-to determine which number is bigger'
	DB	10, 13, '<-to determine which number is smaller'
        DB      10,13,'$'
Newline DB      10,13,'$'


.CODE
CALC	PROC
        mov ax, @data
        mov ds, ax
	 _PutStr Msg1
	 
START:
	_PutStr	Newline
        _PutStr Msg2
        _GetCh 
        push	ax        
	_PutStr	Newline
	pop	cx        

        cmp cl,'#'
        je DOENTER
	
	cmp cl, '?'
	je DOMENU
	
        cmp cl,'+'
        jne NOTADD
        pop AX
        pop BX
        call DOADDI
        jmp DONE
        
        
NOTADD:  
        cmp cl,':'
        je DODISPLAY
        
        cmp cl,'-'
        je DOSUB
        
        cmp cl,'*'
        je DOMUL
        
        cmp cl,'/'
        je DODIV
        
        cmp cl,'r'
        je DOSQR 
        
        cmp cl,'!'
        je DOFAC 
        
        cmp cl,'f'
        je DOREC 
        
        cmp cl,'%'
        je DOREM
        
        cmp cl,'h'
        je DOHEX

        cmp cl,'<'
        je DOSMALL
        
        cmp cl,'>'
        je DOBIG
        
        cmp cl,'q'
        je DOQUIT
        
	_PutStr Msg3
	jmp	start

DOMENU:
	call HELP
	jmp START
	
DODISPLAY:
	call DODISPL
	jmp START	
	
DOENTER:
       call ENTER
       jmp DONE

DOSUB:	
        pop BX
        pop AX
        call DOSUBI
        jmp DONE
        
DOMUL:	
        pop BX
        pop AX
        call DOMULI
        jmp DONE 
        
DODIV:	
        pop AX
        pop BX
        call DODIVI
        jmp DONE 
        
DOHEX:	
	pop AX
	call DOHEXI
        jmp DONE 
        
DOREM:	
        pop AX
        pop BX
        call DOREMI
        jmp DONE   
        
DOSQR:	
        pop AX
        call DOSQRI
        jmp DONE    
        
DOFAC:	
	pop AX
	call DOFAC1
        jmp DONE

DOREC:	

	pop AX
	call DOFAC2
        jmp DONE
        
DOSMALL:	

	pop AX
	pop BX
	call DOMIN
        jmp DONE
        
DOBIG:	

	pop AX
	pop BX
	call DOMAX
        jmp DONE

DONE:   
	push	AX
        call    PutDec		;;Output the number.
	_PutStr	Newline
	jmp	Start

DOQUIT:
        mov al, 0
        mov ah, 4ch
        int 21h
CALC	ENDP


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;SUBPROGRAMS;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

HELP    PROC
	_PutStr Helpmsg		;;Outputs the list of operations
	ret
HELP    ENDP

ENTER   PROC
	_PutStr Prompt1         ;;Receives first number
	call GetDec
	ret
ENTER    ENDP

DOADDI	PROC
	add AX,BX		;;Add
	ret
	
DOADDI    ENDP

DOSUBI	PROC
	sub AX,BX		;;Subtract
	ret
DOSUBI    ENDP

DOMULI	PROC
	imul BX			;;Multiply
	ret
DOMULI    ENDP

DODIVI	PROC
	cwd
	idiv BX			;;Divede
	ret
DODIVI    ENDP


DOREMI	PROC
	cwd
	idiv BX			;;Divede with a remainder
	mov AX,DX
	ret
DOREMI    ENDP

DOHEXI	PROC
	call PutHex		;;Conver to a hexidecimal
	ret
DOHEXI    ENDP

DODISPL	PROC
REPEAT: 
	pop AX
	call    PutDec			
	_PutStr	Newline		;;Display the stack
	jmp REPEAT
	ret
DODISPL    ENDP

DOFAC1	PROC
	mov CX,AX
	mov AX,1
	cmp CX,1
	jle FINISH		;;Regular Factorial
NEXT:
	mul CX
	dec CX
	jg NEXT	
FINISH:
	ret

DOFAC1    ENDP

DOFAC2	PROC
	cmp AX,1
	jg GO
	mov AX,1
	ret
GO:				;;Recurcive Factorial
	push AX
	dec AX
	call DOFAC2
	pop CX
	mul CX
	ret
DOFAC2    ENDP

DOMAX	PROC
	cmp AX,BX
	jge DO1			;;Bigger Number
DO1:
	ret
DOMAX    ENDP

DOMIN	PROC
	cmp AX,BX		;;Smaller Number
	jle DON2
	mov AX,BX
DON2:
	ret
DOMIN    ENDP

DOSQRI	PROC
	mov dx,0
 	mov ax,bx 
 	mov bx,1 
 
loop_start:
 	div bx 
	add ax,bx 
 	ror ax,1 
	xchg ax,bx 
	mov A,ax 		;;Square root
	sub ax,bx 
	jnc positive_diff
 	neg ax
positive_diff:
 	mov dx,0
 	cmp ax,3 
 	jnb loop_start 
	mov ax,A
	ret
DOSQRI    ENDP

	END	CALC