.import serial_setup, serial_print_char, serial_recv_char
.import copy_data

; ---------------
;       ZP
; ---------------
.zeropage
; Zero-page variables ($0000 - $00ff)

; ---------------
;       BSS
; ---------------
.bss
; RAM variables ($0200 - $7fff)

; ---------------
;      DATA
; ---------------
.data
; Initialized RAM variables ($0200 - $7fff)

; ---------------
;      CODE
; ---------------
.code
; Actual program code ($c000 - $fff9)
reset:                              ; Program starts here
; System setup
    sei                             ; disable interrupts while setting things up
    cld                             ; clear BCD mode flag (undefined on NMOS 6502, auto cleared on 65C02)
    ldx #$ff
    txs                             ; Reset stack pointer

    jsr copy_data                   ; copy data variables from ROM to RAM

    jsr serial_setup                ; setup serial interface (65C51N). 19200 baud set as default

print_hello_world:
    ldx #0
@loop:
    lda str_hello_world,x           ; get char
    beq @end                        ; IF char is 0, done
    jsr serial_print_char           ; send char to console
    inx                             ; increment x (next char)
    jmp @loop
@end:
    jmp @end


irq_handler:                        ; IRQ Handler
    rti                             ; Do nothing

nmi_handler:                        ; NMI handler
    rti                             ; Do nothing


; ---------------
;     RODATA
; ---------------
.rodata
; Constants
str_hello_world: .asciiz "Hello, World!"


; ---------------
;     VECTORS
; ---------------
.segment "VECTORS"
; NMI, RESET and IRQ vectors
.word nmi_handler
.word reset
.word irq_handler