;ourcodeimage. Program for our cpu
;===================================
constant
    forever 1 ;while loop
	; ports
 	switches 0 ; in port 0
	sram_data 1  ; in port 1
	sync 2     ; in port 2
	cpu_id 3   ; in port 3
	rom_data 4 ; in port 4
	rom_addr 4 ; out port 4
	LEDred 3   ; output port 3
	
    ; vga_cntl:
    vga_cntl 2  ; out port 2
	sram_cntl 2  ; out port 2
    vga_addr 0;
	vga_data 1; out port 1
	sram_data 1

	; vga color codes
	white 255
	black 0
	gray1 21
	gray2 42
	gray3 63
	gray4 170
	gray5 213
	gray6 234
	red 240
	yellow 252
	green 204
	cyan 207
	
	
	zero 48 ; ascii zero
	a 97 ; ascii lower case 'a'
	;line directions
	up 0
	down 1
	
	
;=====================================
		
	
;======================================	
;Variable definitions
variable
    direction
    rand   ; low order random
	rand2  ; high order random
    temp ; needed for random num generator
	
	; putstr state
	vga_putstr_count
	vga_putstr_x
	vga_putstr_y
	vga_putstr_color
	
	; puthex state
	vga_puthex_x
	vga_puthex_y
	vga_puthex_color
	vga_puthex_value
	vga_puthex_count
	vga_puthex_shift	
	
	count ;point index
	color
	x1 ;for drawing lines
	x2
	y1
	y2
	dy
	dx
	s1
	s2
	y_temp
	x_temp
	e
	xchange
	ychange ;for drawing lines
	
	num2char_num ; used in num2char
	num2char_xpos;
	
	;variables for max and min functions
	max1
	max2
	min1
	min2

   ;two lines
    line1y1
    line1y2
    line1color
;=======================================

;=======================================
;Inline Functions
inline vga_point; x in stack-top, y in next, color in 3rd
   ; stack: color ycoord xcoord (top)
   ; store lower bit of x in 4
   ; and store shifted x to 5
   dup
   1 band pop.4 ; low order bit
   1 shr pop.5 ; 9 high bits
   ; y on stack, shift it 9 left
   9 shl
	; then OR with 9 bits of x
   push.5 bor out[vga_addr]
   ; color is top of stack
   ; if low bit of x is set, shift color to high byte
   if push.4 then 8 shl endif
   out[vga_data] 
   ; now zero we with low x-bit in bit-1
	push.4 1 shl 
	; ask for access (and set up write bits)
	4 bor out[vga_cntl] 
	; now wait for access
   while in[sync] not do endwhile 
   ;clear access and turn off write-bit (0)
   1 out[vga_cntl]
endinline

inline vga_read ; x in stack-top, y in next
   ; input stack: ycoord xcoord (top)
	; output: color
   ; store lower bit of x in 4
   ; and store shifted x to 5
   dup
   1 band pop.4 ; low order bit
   1 shr pop.5 ; 9 high bits
   ; y on stack, shift it 9 left
   9 shl
	; then OR with 9 bits of x
   push.5 bor out[vga_addr]
	; set up control
	; with write-enable high (bit 0)
   ; bit 2 is request for memory
	5 out[vga_cntl] 
 	; now wait for access
	while in[sync] not do endwhile 
	in[sram_data]
	; clear access bit 2
	1 out[vga_cntl] 
   ; if low bit of x is set, shift color to low byte
   if push.4 then 8 shr endif
   ; color is now on stack
endinline

inline sram_read ; 16 bits
; stack: addr (top)
; output: 16 bit value
	out[sram_addr]
	5 out[sram_cntl] ; access (bit 2) + read (bit 0)
	while in[sync] not do endwhile
	in[sram_data]
   ;clear access and turn off write-bit (0)
   1 out[vga_cntl]
endinline

inline sram_write ; 16 bits
	; stack: data addr (top)
	out[sram_addr]
	out[sram_data]
	12 out[sram_cntl] ; access (bit 2) + full word (bit 3)
	; now wait for access
   while in[sync] not do endwhile 
   ;clear access and turn off write-bit (0)
   1 out[vga_cntl]
	nop. ; needed for timing to next event
endinline
;====================================


; ===================================
function
	rand_bit
	vga_putchar
	vga_putstr
	vga_puthex
	vga_line
	num2char
	max
	min
	rand_bit_mult
; ===================================


;===================================================================================================
;;;;Actual program
program
main:
;cli
;nop.
;sei
; nchars color y x

0 =line1y1
479 =line1y2
255 =line1color


;set the (50.4 MHz)timer overflow value
252000  setTimerOverflow ;50400 for 1ms
;draw a few lines; color, x1, y1, x2, y2
line1color 0 line1y1 639 line1y2 vga_line
;set line direction
down =direction
;
"ECE cyan 20 280 vga_putstr
"5760 cyan 20 320 vga_putstr
"Pancake gray6 40 240 vga_putstr
"With gray6 40 310 vga_putstr
"Interrupts gray6 40 350 vga_putstr
;;;;
while forever
do 
	nop.
endwhile
;================================

;===============================
; VGA put hex num2char_num
;===============================
; enters with an 18-bit value on the stack
; to print to VGA
; stack: value color y x (top)
vga_puthex:
	=vga_puthex_x
	=vga_puthex_y
	=vga_puthex_color
	=vga_puthex_value
	
	5 =vga_puthex_count ; num2char_num of digits to print
	16 =vga_puthex_shift ; shift factor
	while vga_puthex_count 0 gt
	do
	   vga_puthex_value vga_puthex_shift shr 15 band
	   if dup 10 lt
	   then zero add 
	   else 10 sub a add
	   endif
	   vga_puthex_color vga_puthex_y vga_puthex_x 
		vga_putchar
		; update counter and shift for next digit
	   vga_puthex_count 1 sub =vga_puthex_count 
	   vga_puthex_shift 4 sub =vga_puthex_shift 
		vga_puthex_x 8 add =vga_puthex_x 
	endwhile
return

;===============================
; VGA put character
;===============================
; enters with a 8-bit character
; x coordinate and y coordinate
; and color
; stack: char color y x (top)
vga_putchar: 
	pop.8 ; store x
	pop.9 ; store y
	pop.6 ; store color
	4 shl pop.7 ; store char*16
	0 pop.11 ; init y counter
	while push.11 16 lt
	do
		push.7 push.11 add out[rom_addr] ; line of char in rom
		0 pop.10 ; init bit counter (x)
		while push.10 8 lt
		do
			; get the line and shift it so always
			; check high bit of byte and set color
			if in[rom_data] push.10 shl 128 band 
			then push.6 else black endif
			; form y
			push.9 push.11 add
			; form x
			push.8 push.10 add
			vga_point ; write the point
			; x position update
			push.10 1 add pop.10
		endwhile
		; y position update
		push.11 1 add pop.11
	endwhile	
return

;===============================
; VGA put string
;===============================
; enters with stack:
; nchars n... color y x (top)
; count n on the stack 
; followed by n characters on the stack
vga_putstr:
	=vga_putstr_x
	=vga_putstr_y
	=vga_putstr_color
	=vga_putstr_count
	while vga_putstr_count 0 gt
	do
	   vga_putstr_color vga_putstr_y vga_putstr_x 
		vga_putchar
		vga_putstr_x 8 add =vga_putstr_x 
	   vga_putstr_count 1 sub =vga_putstr_count
	endwhile
return

;===============================
; random num2char_num generator
;===============================
; from "Art of Electronics" page 657
; entry: uses nothing on stack
; exit: +1 or -1 on stack.Modified to 1 or 0 on stack. Useful for generating n-bit numbers
; 36-bit shift reg:
; shift left one bit
; bits 36 and 25 XORed (2nd reg bit 17 and 6)
; and stored to bit 0
rand_bit: 
    ; get high order rand register and copy for xor
    ; shift left to align bits 17 and 6
    ; bitwise xor
    ; move bit 17 to bit 0
    ; save xor bit for later
    rand2 dup 11 shl bxor 17 shr =temp

    ; modify rand2 by shifting in the high
    ; order bit from rand --
    ; get rand and shift right 17
    ; get rand2 shl 1-bit and OR with
    ; bit from rand
    rand 17 shr rand2 1 shl bor =rand2

    ; modify rand
    ; shift left to open up 0 bit  
    ; get the stored xor bit (in temp)
    ; OR to form new final rand
    ; dup to store and for output
    rand 1 shl temp bor dup =rand

    ; construct +/-1 output
    ; band with 1 to isolate bit 0
    ; mult by 2 and subtract 1
    ; so that final output is +1 or -1    
    1 band ;1 shl 1 sub
	
	;use appropriate bits of random number on the stack
return


;=====================================================
; Draws a colored line between any two points (x1,y1) and (x2,y2)
vga_line: ; color, x1, y1, x2, y2 
  =y2
  =x2
  =y1
  =x1
  =color
  0 =count

  x1 =x_temp
  y1 =y_temp

  ; Takes absolute value of difference and does something to it

  ; Does the x's first
  if x2 x1 lt
  then
    x1 x2 sub =dx
    -1 =s1
  endif

  if x2 x1 eq
  then
    0 =dx
    0 =s1
  endif

  if x2 x1 gt
  then
    x2 x1 sub =dx
    1 =s1
  endif

  ; Now does the y's
  if y2 y1 lt
  then
    y1 y2 sub =dy
    -1 =s2
  endif

  if y2 y1 eq
  then
    0 =dy
    0 =s2
  endif

  if y2 y1 gt
  then
    y2 y1 sub =dy
    1 =s2
  endif

  ; Does some other stuff
  
  0 =xchange

  if dy dx gt
  then
    dy dx
    =dy
    =dx
    1 =xchange
  endif

  dy 1 shl dx sub =e

  while count dx gt not
  do
    color y_temp x_temp vga_point

    if e 0 lt not
    then

      if 1 xchange eq
      then
        x_temp s1 add =x_temp
      else
        y_temp s2 add =y_temp
      endif

      e dx 1 shl sub =e

    endif

    if 1 xchange eq
    then
      y_temp s2 add =y_temp
    else
      x_temp s1 add =x_temp
    endif

    e dy 1 shl add =e

    1 count add =count
  endwhile

return

;=====================================
;simple num2char function for testing
;displays one digit at a time
; num2char_num (top)
num2char: ;num2char_num
   =num2char_num
   num2char_xpos 10 add =num2char_xpos ;update xpos for writing
   if num2char_num 0 eq 
   then 48 white 2 num2char_xpos vga_putchar
   endif
   if num2char_num 1 eq
   then 49 white 2 num2char_xpos vga_putchar
   endif
   if num2char_num 2 eq
   then 50  white 2 num2char_xpos vga_putchar
   endif
   if  num2char_num 3 eq
   then 51  white 2 num2char_xpos vga_putchar
   endif
   if num2char_num 4 eq
   then 52  white 2 num2char_xpos vga_putchar
   endif
   if num2char_num 5 eq
   then 53  white 2 num2char_xpos vga_putchar
   endif
   if num2char_num 6 eq
   then 54  white 2 num2char_xpos vga_putchar 
   endif
   if num2char_num 7 eq
   then 55  white 2 num2char_xpos vga_putchar
   endif
   if num2char_num 8 eq
   then 56 white 2 num2char_xpos vga_putchar
   endif
   if num2char_num 9 eq
   then 57 white 2 num2char_xpos vga_putchar
   endif
      
return
;=======================================	

;=======================================
;max . Works for positive numbers only
;stack :
; max2 max1 (top)
max:
  =max1
  =max2
  if max1 max2 lt not ;max1 >= max2
  then
      max1
  else max2
  endif
return

;==========================================
;min. stack:
; min2 min1 (top)
min:
 =min1
 =min2
 if min1 min2 lt not ;min1>=min2
 then 
	min2
 else min1
 endif
return
;================================================

;===============================
;======begin ISR section
ISR TIMER
if direction down eq
then ;downward direction
	if line1y1 479 lt ;line1y1<479
	then
		line1y1 1 add =line1y1
		line1y2 1 sub =line1y2
		;white =line1color
		line1color 0 line1y1 639 line1y2 vga_line
	else ;line1y1
		up =direction
		gray5 =line1color
	endif
else ;upward direction
	if line1y1 0 gt
	then
		line1y1 1 sub =line1y1
		line1y2 1 add =line1y2
		line1color 0 line1y1 639 line1y2 vga_line
	else; end of upward direction
		down =direction
		gray3 =line1color
	endif
endif
endISR
;=============
;===========Key[1] ISR
ISR KEY1
    ;line1y1 10 add =line1y1
    ;line1y2 10 sub =line1y2
    red =line1color
    ;line1color 0 line1y1 639 line1y2 vga_line
    ;dup drop
endISR
;===========
;===========Key[2] ISR
ISR KEY2
    ;line1y1 10 add =line1y1
    ;line1y2 10 sub =line1y2
    yellow =line1color
    ;line1color 0 line1y1 639 line1y2 vga_line
   ; dup drop
endISR
;=============
;=============
ISR KEY3
    ;line1y1 10 add =line1y1
    ;line1y2 10 sub =line1y2
    green =line1color
    ;line1color 0 line1y1 639 line1y2 vga_line
    ;dup drop
endISR
;==========
;==========
;ISR UNUSED
;endISR
;==========

;================================================================
;End Of Code
;================================================================