aoc_omni/gb/2015/1/not_quite_lisp.asm

INCLUDE "lib/hardware.inc"
INCLUDE "lib/macros.inc"

SECTION "VBlank Interrupt", ROM0[$40]
	jp VBlankHandler

SECTION "Header", ROM0[$100]
	jp EntryPoint
	ds $150 - @, 0 ; Make room for the header

SECTION "Init", ROM0[$150]
EntryPoint:
	StartInit

	ClearScreen
	ClearOAM
	LoadTiles

	MemClear current_frame, 1
	MemClear current_floor, 2
	MemClear done_flag, 1

	;; Initialize input_index
	ld bc, input
	ld a, b
	ld [input_index], a
	ld a, c
	ld [input_index + 1], a

	FinishInit
	ei

CheckInput:	
	ld a, [input_index]
	ld h, a
	ld a, [input_index + 1]
	ld l, a
	ld a, [hl]

	cp a, "("
	jr z, GoingUp
	jr GoingDown
GoingUp:	
	call IncrementCurrentFloor
	jr GoingNowhere
GoingDown:	
	call DecrementCurrentFloor
GoingNowhere:	

	IncrementWord input_index

	ld de, input_end
	ld a, [input_index]
	sub a, d
	jr nz, CheckInput

	ld a, [input_index + 1]
	sub a, e
	jr nz, CheckInput

	ld a, 1
	ld [done_flag], a

Done:	
	
	halt
	nop
	jr Done

IncrementCurrentFloor:
	ld hl, current_floor
	ld a, [hli]
	ld b, a
	ld a, [hli]
	ld c, a

	inc bc

	ld hl, current_floor
	ld a, b
	ld [hli], a
	ld a, c
	ld [hli], a
	
	ret

DecrementCurrentFloor:
	ld hl, current_floor
	ld a, [hli]
	ld b, a
	ld a, [hli]
	ld c, a

	dec bc

	ld hl, current_floor
	ld a, b
	ld [hli], a
	ld a, c
	ld [hli], a
	
	ret
	ret

VBlankHandler:
	push AF
	push BC
	push DE
	push HL
	
	IncrementFrameCount
	PrintByteHex current_frame, 0, 0
	PrintByte current_frame, 0, 1
	PrintByteHex current_floor, 0, 2
	PrintByteHex current_floor + 1, 2, 2
	ld a, [done_flag]
	cp a, 1
	jr z, NotDone
	PrintString done_string, 3, 3

NotDone:	
	pop HL
	pop DE
	pop BC
	pop AF
	reti

SECTION "High RAM", HRAM
current_floor:	DS 2
done_flag:	DS 1

SECTION "Input", ROM0
input:
INCBIN "../data/2015/1/input.txt"
input_end:

done_string:
	db "Done", 0
done_string_end:	

INCLUDE "lib/tiles.asm"