##=================================================================================================================================
## This is the test2 program for the Dragon Virtual Machine. This example simply demonstrates the Virtual Display in Text-Single-Color
## mode, by printing an increasing counter followed by whatever is in the $string variable. The program also clears the screen 
## every 10 lines.
##=================================================================================================================================

.load 0x1740

.data
	$string "Hello World!!"

.code

	mov R10, 0x00
	mov R9, $_text_entered_handler
	mov R8, 0xA2
	int 0x20					## Enable text entered handler

	mov R10, 0x00
	mov R9, $_key_pressed_handler
	mov R8, 0xA0
	int 0x20					## Enable key pressed handler

	mov R10, 0x0B
	int 0x30					## Invert colors

	mov R10, 0x01
	mov R9, 62
	int 0x30					## Print first prompt char

	mov R10, 0x0B
	int 0x30					## Invert colors

	mov R10, 0x01
	mov R9, 32
	int 0x30					## Print space


	mov R1, 0					## Zero the counter 
infinite_loop:
	inc R1						## Increment the counter
	div R1, 10					## Divide the counter by 10
	mov ACC, RV				
	jne $no_clear_screen, 0 	## If reminder not zero, keep going
	mov R10, 0xE0				## Else clear the screen (0x0E is for 'Clear Screen' functionality in int 0x30)
	##int 0x30					## BIOS Video Interrupt
no_clear_screen:

	## Print counter
	mov R9, R1					## Pass the counter as parameter to int 0x30
	mov R10, 0x05				## 0x05 is for 'Store Integer in buffer' functionality in int 0x30
	##int 0x30					## BIOS Video Interrupt

	## Print a space
	mov R9, 32					## Pass 32 (space character in ASCII) as parameter to int 0x30
	mov R10, 0x06				## 0x06 is for 'Store Character in buffer' functionality in int 0x30
	##int 0x30					## BIOS Video Interrupt

	## Print the string
	mov R9, $string				## Pass the address of the string as parameter to int 0x30
	mov R10, 0x0A				## 0x0A is for 'Store String in buffer' functionality in int 0x30
	##int 0x30					## BIOS Video Interrupt

	## Print a new-line character
	mov R10, 0x02				## 0x02 is for 'Print New-Line' functionality in int 0x30
								## Printing a new line when in Text-Single-Color Mode also
								## prints and flushes the buffer
	##int 0x30					## BIOS Video Interrupt

	jmp $infinite_loop			## jump to the beginning of infinite loop
	hlt

_text_entered_handler:
	mov R9, [0x1282]
	mov R10, 0x01
	int 0x30
	rti

_key_pressed_handler:
	mov ACC, [0x1282]
	jeq $_key_pressed_handler_backspace, 8
	jne $_key_pressed_handler_end, 13
	mov R10, 0x02
	int 0x30
	mov R10, 0x0B
	int 0x30					## Invert colors
	mov R10, 0x01
	mov R9, 62
	int 0x30
	mov R10, 0x0B
	int 0x30					## Invert colors
	mov R10, 0x01
	mov R9, 32
	int 0x30
	jmp $_key_pressed_handler_end
_key_pressed_handler_backspace:
	debug_break
	mov R9, ACC
	mov R10, 0x01
	int 0x30
_key_pressed_handler_end:
	rti


.fixed 512, 0x00