;Chris Twardzicki
;Mandelbrot Set, MC160 Project
;twardzic@bc.edu
;******************************************************************
;The Mandelbrot set is defined as: For each complex number C, 
;a sequence of iterations Zn is defined as:
;			z0=(0+0i)
;		   	zn=(zn-1^2) + C
;If the sequence remains within a distance of 2 of the origin
;forever, then z0 is said to be in the mandelbrot set.
;******************************************************************


.model small
.stack 200h
.386


;Screen corners (-2,-2),(2,2)
;Transformation between real and integer coordinates:
;x=(u-320)/160, y = (240-v)/120
.data
u			dw	?
v			dw	?
dist		dd	?
color		dw	?
y			dd	?
x			dd	?
loopvar		dd	0
previousx 	dd	0.0
previousy 	dd	0.0
newX		dd	0.0
newY		dd	0.0
variable	dd	0.0
variable2	dd	0.0
CCXL		dd	240.0
CCCXX		dd	320.0
VIII		dd	8.0
TWO			dd	2
TOO			dd	2.0
junk        dd      ?
status      dw      ?
ONETWENTY	dd	120.0	
ONESIXTY	dd	160.0

.code
.startup
mov	ah,0		;set color video mode
mov	al,12h
int	10h
mov	bh,0	

finit
mov	v, 0

a_loop:
mov	u, 0

b_loop:
mov loopvar, 0
mov previousx, 0
mov previousy, 0
fild	u	;u is placed onto the copro stack
fld	CCCXX	;320 is placed onto the copro stack
fsub	;u-320 is placed onto the stack
fdiv	ONESIXTY	;(u-320)/160 is placed onto the stack
fstp x	;stores (u-320)/160 in x and popped

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

fld	CCXL	;240 is placed onto the copro stack
fild	v	;v is placed onto the copro stack
fsub	;(240-v) on top of the stack
fdiv	ONETWENTY	;(240-v)/120 on top of stack
fstp	y	;(120-v)/120 is stored into y and popped

;intially z0 = (0+0i), so we move 0 into previousx and previousy
mov previousx, 0
mov previousy, 0

iterate:
fld previousx	;pushes previousx onto stack
fmul previousx	;previousx^2
fld previousy	;pushes previousy onto stack
fmul previousy	;previousy^2
fsub	;(previousx^2)-(previousy^2) on stack
fld x	
fadd	;(previousx^2)-(previousy^2)+x on stack
fstp newX 	;stores above equation into newX and pops

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

fld previousy	;pushes previousy onto stack
fld previousx	;
fmul 		;previousx*previousy on stack
fld TOO	
fmul	;previousx*previousy*2 on stack
fld y
fadd	;previousx*previousy*2+y
fstp newY	;stores above equation into newY and pops


;this simply does previousx = newX and previousy = newY
fld newX	;load newX onto stack
fstp previousx	;store newX into previousx and pop 
fld newY	;load newY onto stack
fstp previousy	;store newY into previousy and pop

inc loopvar	;loop counter is incremented

cmp loopvar, 1000	;the incremented loop counter,which is on top of the stack,
					;is compared to 1000, and pops it off the stack

jl iterate	;jump if loop counter is less than one hundred to iterate again.

;finally applying the full distance equation
fld newX	;pushes newX onto stack
fmul newX	;newX^2
fld newY	;pushes newY onto stack
fmul newY	;newY^2
fadd	;adds (newX^2)+(newY^2) onto the stack
fsqrt 	;sqrt((newX^2)+(newY^2)) on the stack

fst dist	;stores the top of the stack, the distance, into dist, just in case!

fcomp TWO	;compares the distance equation of the iterated points to 2, & pops it
fstsw status  	        ;save the status register
fstp    junk            ;get rid of top of stack
fld     dist               ;and put dist back
and     status,4500h    ;mask three bits
jz plotwhite	;if it is less than 2, it is in the set, so we jump to 
;plotwhite, else  it isn't in the set, and we write the pixel in green

;Now get ready to write pixel in green, a point in the not in the mandelbrot set
mov	ax,10
mov	ah,0ch
mov	cx,u
mov	dx,v
int	10h
jmp increment

plotwhite:
;Now get ready to write pixel in white, a point in the set
mov	ax,15
mov	ah,0ch
mov	cx,u
mov	dx,v
int 10h

increment:
inc	u
cmp	u,640
jl	b_loop
inc	v
cmp	v,480
jl	a_loop
;Here's a delay that requests keyboard input and
;waits for key pressed

mov	ah,10h
int 	16h

;Now set back to text mode
mov	ah,0
mov	al,3
int	10h
.exit
end