;==================================================================================
;File        :ulum.asm
;Author      :Andre Long
;Due         :Febuary 27, 2006
;Description :Generate a sequence of numbers via Ulim's Conjecture
;==================================================================================
								;External Procedures
								
INCLUDE   Pcmac.inc
EXTRN     NEWLINE: FAR			;Display Newline
EXTRN     GETDEC$: FAR			;Gets 16-Bit Decimal Unsigned
EXTRN     PUTDEC$: FAR          ;Display 16-Bit Decimal Unsigned
EXTRN     PUTSTRNG:FAR          ;Display Character String
;==================================================================================
		.MODEL SMALL
		.586
		.STACK 100h
		
		.DATA
Welcome		DB	"Welcome to Ulum's World ", 13, 10, '$'
getInput	DB	"Enter a positive whole number: ", '$'
outPut		DB	"Ulum's sequence is : ", 13, 10, '$'
messError	DB	" Overflow Occured! ", 13, 10, '$'
counter		DW	0
messInput	DB	"The number you entered is: ", '$'
messEven	DB	13, 10, "Even number ", '$'
messOdd		DB	13, 10, "Odd number ", '$'
messCount	DB	" Counter= ", '$'
space		DB	" ",'$'
messSequen	DB	"The number sequence is: ",13, 10, '$'
lineNumber	DW	1
;==================================================================================
		.CODE
main	proc
		_Begin							;Macro for boiler plate
		sPutStr		Welcome				;Safe version of putstr
		call		Newline
		
green:	sPutStr		getInput
		call		GETDEC$				;Gets value from keyboard & stores in AX
		sPutStr		messInput
		mov			bh,		0			;Display mode for 'PUTDEC' (no blanks)
		call		PUTDEC$				;Display AX register (unsigned)
		call		Newline
		sPutStr		messSequen
		
ntest:	push		ax					;Save a copy of AX on the stack
		mov			bx,		2
		mov			dx,		0
		div			bx					;Ax = Dx:Ax / bx
		cmp			dx,		0			;dx is where remainder is stored
		pop			ax					;Restore Ax
		je			nEven
		jmp			nOdd
		
nEven:	;sPutStr	messEven			;For testing / debugging
		mov			dx,		0			;Make sure 'dx' is not garbage
		mov			bx,		2
		div			bx					;Ax = Dx:Ax / bx
		add			counter,1
		mov			bh,		1
		call		PUTDEC$				;Display value X/2
		sPutStr		space
		add			lineNumber,	1
		cmp			lineNumber, 10
		ja			ptX
		jmp			ptY
		
ptX:	call		Newline
		mov			lineNumber,	1

ptY:	mov			cx,		counter
		push		ax
		mov			ax,		cx
		pop			ax
		cmp			ax,		1
		ja			ntest
		jmp			exit
		
nOdd:	;sPutStr	messOdd				;For testing / debugging
		mov			bx,		3
		mul			bx					;Ax = Ax*bl (bl=3)
		jo			messO
		mov			bx,		1
		add			ax,		bx			;Ax = Ax + bx (bx=1)
		jc			messO
		jo			messO
		add			counter,1
		mov			bh,		1
		call		PUTDEC$				;Display value (X*3)+1
		sPutStr		space
		add			lineNumber,	1
		cmp			lineNumber, 10
		ja			ptXX
		jmp			ptYY
		
ptXX:	call		Newline
		mov			lineNumber,	1
		
ptYY:	mov			cx,		counter
		push		ax
		mov			ax,		cx
		pop			ax
		cmp			ax,		1
		ja			ntest
		jmp			exit
		
messO:	sPutStr		messError

exit:	call		Newline
		sPutStr		messCount
		mov			ax,		cx
		call		PUTDEC$	
		
		mov			ah,		4ch			;Exit back to DOS
		int			21h
main	ENDP
		END main