;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
.debuginfo      +       ; Generate debug info
;;Macros
.include "macros/16bitarithmetic.s"
;;inc files
.include "routines/memory/mem.inc"
;;Code to run
.include "STARTUP.s"
;.include "routines/line/line_test_time.s"
;;.include "routines/memory/memcpy_test.s"
;.include "fillscreen.s"
;Hacky hardcoding. I pick FC and FD to contain the 16 bit offset to the screen
LDA #$40 ;Remember kids, C64 is a little endian computer. Why, why why! Big endian makes more sense!
STA $FD ;THis means that the bitmap starts at $4000
LDA #$00
LDX #$60
STA $FC

mainloop:
;fill screen with white pixels
LDY #$00
LDA #%10000000 ; Start out with setting the leftmost pixel to white in every byte in the bitmap
STA $FF ;$FF contains the pattern we are writing to part if the bitmap memory
STA $FE ;$FE conatins the most recent bit/pixel we are adding
;The idea is now to bitshift this to the right, until A is 0. When this happens it is time to update which byte we are working on
pixel_setting_loop:
LDA $FF
STA ($FC),Y
LDA $FE ;FE contains the most recent bit/pixel we are adding
LSR a
BNE more_pixels_in_byte
INC $FC
; if this overflows
BNE not_incrementing_other_byte
INC $FD
CPX $FD
; if the carry flag is zero, branch
BCC done_pixels
not_incrementing_other_byte:
LDA #%10000000
STA $FE
STA $FF
more_pixels_in_byte:
STA $FE ;$FE conatins the most recent bit/pixel we are adding
ORA $FF ;Add the previous pixels.
STA $FF
JMP pixel_setting_loop
done_pixels:
;check is somebody has pressed space and if so exit, code blatantly stolen from Duuqnd
LDX #%01111111
LDY #%00010000
LDA #$ff
STA $DC02
LDA #$00
STA $DC03
STX $DC00
TYA
AND $DC01
;Check if A is 0
BEQ die
jmp mainloop
die:
;.include "routines/line/line.s"
;.include "routines/memory/pixel_draw.s"
.include "routines/memory/memset.s"
;.include "routines/memory/memcpy.s"