.org 0

.equ INT_VECTOR 0xff00

    call init
    call init_game

game_loop:
    halt

    call entities_erase
    call stars_update
    call entities_update
    call entities_draw

    jmp game_loop

init:
    ; setup an int handler so we
    ; can use the frame int to sync
    ld a, >INT_VECTOR
    ld x, <INT_VECTOR
    ld b, <int_handler
    ld [a : x], b
    inc x
    ld b, >int_handler
    ld [a : x], b

    ; enable interrupts
    cif
    ret

init_game:
    halt

    ; set player initial coordinates
    ld x, <player_coord
    ld a, >player_coord

    ld y, 56
    ld [a : x], y
    inc x
    bo
    inc a
    ld y, 104
    ld [a : x], y

    ; erase the screen
    ld b, 0
    ld a, 0xbf
    ld x, 0
    ld y, 0x40
fill_loop:
    ld [a : x], b
    inc x
    bno
    jmp fill_loop
    inc a
    dec y
    bnz
    jmp fill_loop

    call entities_draw

    ret

int_handler:
    iret

.include "random.asm"
.include "starfield.asm"
.include "entities.asm"
.include "player.asm"

;
; entity data
;
entities:
    ; type
    .db ET_PLAYER
    ; x, y
player_coord:
    .db 0, 0
    ; frame
    .db 0
    .dw player_sprite
    .dw player_update

    ; end of list
    .db ET_END

; sprite data
player_sprite:
    .incpng "assets/player.png"

; starfield data
stars:
    ; video addr, speed, color
    .dw 0xc361
    .db 1, 15
    .dw 0xc204
    .db 1, 6
    .dw 0xcdf9
    .db 1, 15
    .dw 0xdb87
    .db 1, 3
    .dw 0xd242
    .db 1, 15
    .dw 0xdeea
    .db 1, 6
    .dw 0xe7af
    .db 1, 15
    .dw 0xed68
    .db 1, 3
    .dw 0xf812
    .db 1, 15
    .dw 0xfbca
    .db 1, 13
    .dw 0xc361
    .db 2, 8
    .dw 0xc204
    .db 2, 9
    .dw 0xcdf9
    .db 3, 7
    .dw 0xdb87
    .db 3, 4
    .dw 0xd242
    .db 2, 8
    .dw 0xdeea
    .db 3, 9
    .dw 0xe7af
    .db 3, 6
    .dw 0xed68
    .db 2, 9
    .dw 0xf812
    .db 3, 14
    .dw 0xfbca
    .db 2, 3
    ; end of list
    .dw 0xffff