#define __SFR_OFFSET 0
#include <avr/io.h>

.global main
.global TIMER1_COMPA_vect

; --- GLOBAL REGISTER ---
; r17 = Status Target (1: Drone/Hijau, 2: Rudal/Merah)
; r19 = Counter Urutan (0: hijau, 1: merah)
; r25 = Flag tombol ditekan (0: belum, 1: sudah)
; r24 = Counter tick Timer (tiap tick = 1 detik, target = 2)

.section .text

; === INTERRUPT VECTOR TABLE ===
.org 0x0000
    rjmp main

.org 0x0016
    rjmp TIMER1_COMPA_vect  ; Timer1 Compare Match A vector

.org 0x0034
main:
    ; Setup Stack Pointer
    ldi r16, hi8(RAMEND)
    out SPH, r16
    ldi r16, lo8(RAMEND)
    out SPL, r16

    ; Setup I/O
    sbi DDRB, 0         ; PB0 Output → LED Merah
    sbi DDRB, 1         ; PB1 Output → LED Hijau
    cbi DDRD, 2         ; PD2 Input  → Tombol
    sbi PORTD, 2        ; Aktifkan Pull-Up PD2

    ; Setup UART 9600 Baud
    clr r16
    sts UCSR0A, r16
    sts UBRR0H, r16
    ldi r16, 103
    sts UBRR0L, r16
    ldi r16, (1<<RXEN0)|(1<<TXEN0)
    sts UCSR0B, r16
    ldi r16, (1<<UCSZ00)|(1<<UCSZ01)
    sts UCSR0C, r16

    ; === Setup Timer1 CTC Mode ===
    ; Target: interrupt setiap 1 detik
    ; Rumus: OCR1A = (F_CPU / (Prescaler * Target_Hz)) - 1
    ;        OCR1A = (16.000.000 / (256 * 1)) - 1 = 62499
    ;
    ; TCCR1A = 0 (CTC mode, no PWM output)
    ; TCCR1B = WGM12 | CS12 (CTC mode, prescaler 256)

    clr r16
    sts TCCR1A, r16

    ldi r16, (1<<WGM12)|(1<<CS12)
    sts TCCR1B, r16

    ; Set OCR1A = 62499 = 0xF423
    ldi r16, 0xF4
    sts OCR1AH, r16
    ldi r16, 0x23
    sts OCR1AL, r16

    ; Reset TCNT1
    clr r16
    sts TCNT1H, r16
    sts TCNT1L, r16

    ; Enable Timer1 Compare Match A Interrupt
    ldi r16, (1<<OCIE1A)
    sts TIMSK1, r16

    ; Inisialisasi register
    ldi r19, 0          ; Urutan mulai dari hijau
    clr r25             ; Flag tombol = 0
    clr r24             ; Tick counter = 0

    ; Enable Global Interrupt
    sei

loop_utama:
    cbi PORTB, 0
    cbi PORTB, 1
    clr r25             ; Reset flag tombol
    clr r24             ; Reset tick counter Timer

    cpi r19, 1
    breq set_rudal

set_drone:
    ldi r17, 1
    sbi PORTB, 1        ; LED Hijau ON
    inc r19
    rjmp tunggu_dan_cek

set_rudal:
    ldi r17, 2
    sbi PORTB, 0        ; LED Merah ON
    ldi r19, 0

tunggu_dan_cek:
    ; Tunggu sampai r24 == 2 (2 tick = 2 detik)
    ; Selama menunggu, ISR Timer bisa increment r24
    ; dan tombol bisa dicek setiap saat
tunggu_loop:
    ; Cek tombol secara polling di dalam tunggu_loop
    sbis PIND, 2        ; Skip jika tombol tidak ditekan (HIGH)
    ldi r25, 1          ; Tombol ditekan (LOW) → set flag

    ; Cek apakah sudah 2 detik
    cpi r24, 2
    brlo tunggu_loop    ; Belum 2 detik, terus tunggu

    ; 2 detik selesai → evaluasi
    cpi r25, 1
    brne cek_missed

    cpi r17, 2
    breq hit_rudal      ; Merah + ditekan = BERHASIL
    rjmp hit_drone      ; Hijau + ditekan = SALAH TEMBAK

cek_missed:
    cpi r17, 2
    breq missed_rudal
    rjmp loop_utama

missed_rudal:
    ldi r30, lo8(msg_gagal)
    ldi r31, hi8(msg_gagal)
    call uart_print
    rjmp loop_utama

hit_rudal:
    ldi r30, lo8(msg_sukses)
    ldi r31, hi8(msg_sukses)
    call uart_print
    rjmp loop_utama

hit_drone:
    ldi r30, lo8(msg_gagal)
    ldi r31, hi8(msg_gagal)
    call uart_print
    rjmp loop_utama

; === ISR TIMER1 COMPARE MATCH A ===
; Dipanggil otomatis setiap 1 detik oleh hardware Timer1
; TCNT1 otomatis di-reset ke 0 karena mode CTC
TIMER1_COMPA_vect:
    inc r24             ; Tambah tick counter (+1 detik)
    reti

; === UART PRINT ===
uart_print:
    lpm r18, Z+
    cpi r18, 0
    breq print_end
uart_wait:
    lds r16, UCSR0A
    sbrs r16, UDRE0
    rjmp uart_wait
    sts UDR0, r18
    rjmp uart_print
print_end:
    ret

msg_sukses:
    .asciz "INTERCEPT BERHASIL!\r\n"
msg_gagal:
    .asciz "MISSED TARGET!\r\n"