;==========================
; Author: Marcel Schirmer 
; Date:   31.05.2025
;==========================

.nolist
.include "./m328Pdef.inc"
.list

.def setter     = R16
.def overflows  = R17
.def active_led = R18
.def btn_status = R19
.def cur_direction    = R20

.equ L2R            = 0x01
.equ R2L            = 0b00000100
.equ RBTN_PRESSED   = 0b00000100
.equ LBTN_PRESSED   = 0b00000001

.org 0x0000
    rjmp init
.org 0x0020
    rjmp overflow_handler

.include "./macros.inc"

init:
    ;--
    ; Output Ports definieren
    ;----
    ser setter
    out DDRD, setter            ; Alle PortD Pins als OUTPUT

    ;--
    ; Taster Pins definieren
    ;----
    ; ldi setter, 0b11111010
    ser setter
    out DDRB, setter            ; PB0 und PB2 als Inputs definieren
    ; ldi setter, 0b00000101
    ; out PORTB, setter           ; Interne Pullups aktivieren
    clr setter
    out PORTB, setter

    ;--
    ; Timer/Counter konfigurieren
    ;----
    ldi setter, 0b00000011
    out TCCR0B, setter          ; CLK/1024 ergibt 250.000 Timer-Ticks/Sekunde
    ldi setter, 0b00000001
    sts TIMSK0, setter          ; Timer-Interupt aktivieren
    sei                         ; globale Interrups aktivieren

    ;--
    ; Definiere Startzustand
    ;----
    ldi setter, 0
    out TCNT0, setter           ; Timer/Counter explizit mit 0 initialisieren
    ldi setter, 0b00000001
    out PORTD, setter           ; erste LED einschalten
    clr btn_status              ; initialer Status = kein Taster gedrückt
    ldi cur_direction, L2R      ; initial mit Laufrichtung von links nach rechts starten

loop:
    ;--
    ; Dreh Dräumchen und lass den Timer-Interrupt die Show leiten
    ;----
    rjmp loop

overflow_handler:
    inc overflows
    cpi overflows, 246                  ; bei ~980 Überläufe/Sekunde entsprechen 245 Überläufe ca. 250ms
    brne ret_overflow_handler          ; early Return wenn Schwellenwert noch nicht erreicht
        clr overflows                   ; Überlaufzähler kontrolliert zurücksetzen
        in btn_status, PINB

        cpi btn_status, 0
        breq run_animation

        cp cur_direction, btn_status
        breq run_animation

        ;--
        ; Setze definierten Start für den 
        ; Laufrichtungswechsel
        ;----
        cpi btn_status, LBTN_PRESSED
        brne PC+3
            ldi setter, 0b10000000
            ldi cur_direction, L2R

        cpi btn_status, RBTN_PRESSED
        brne PC+3
            ldi setter, 0b00000001
            ldi cur_direction, R2L

        out PORTD, setter
        ; mov cur_direction, btn_status
        ; ldi setter, 0b10000000
        ; cpi btn_status, RBTN_PRESSED
        ; breq PC+2
        ;     ldi setter, 0b00000001
        ; out PORTD, setter
        ;------

        run_animation:
            cpi cur_direction, L2R
            brne PC+3
                left_to_right active_led
                reti

            cpi cur_direction, R2L
            brne PC+3
                right_to_left active_led
                reti

        ldi setter, 0b00011000
        out PORTD, setter

        ;====================

        ; cpi btn_status, R2L_PRESSED
        ; brne PC+3
        ;     ldi active_led, 0b00000001
        ;     right_to_left active_led
        ;
        ; cpi btn_status, R2L_PRESSED
        ; brne PC+3
        ;     ldi active_led, 0b10000000
        ;     left_to_right active_led
        ;
        ; cpi btn_status, 0xFF
        ; brne PC+3
        ;     ldi active_led, 0b00000001
        ;     left_to_right active_led

        ;====================

        ; cpi btn_status, 0x00
        ; brne PC+4
        ;     ldi setter, 0b10101010
        ;     out PORTD, setter
        ;     rjmp ret_overflow_handler
        ;
        ; cpi btn_status, RBTN_PRESSED
        ; brne PC+5
        ;     ldi setter, 0b00000001
        ;     out PORTD
        ;     right_to_left active_led
        ;     rjmp ret_overflow_handler
        ;
        ; cpi btn_status, LBTN_PRESSED
        ; brne PC+4
        ;     ldi active_led, 0b00100000
        ;     ; left_to_right active_led
        ;     out PORTD, active_led
        ;     rjmp ret_overflow_handler
        ;
        ; ser setter
        ; out PORTD, setter

    ret_overflow_handler:
        reti