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millfork/include/gb_hardware.mfk
2019-06-26 17:54:29 +02:00

171 lines
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#if not(GAMEBOY)
#warn gb_hardware module should be only used on NES/Famicom targets
#endif
#pragma zilog_syntax
asm void __start() @ $150 {
di
ld sp, $DFFF
xor a
ldh (reg_irq_flag), a
? ld a,ief_vblank
ldh (reg_irq_enable), a
? call disable_lcd
? call clear_ram
// copy the DMA routine to hi RAM
ld hl, __sprite_dma_template
ld de, __sprite_dma_actual
ld c, __sprite_dma_actual.length
__copy_sprite_dma_template:
ld a,(hli)
ld (de),a
inc de
dec c
jr nz, __copy_sprite_dma_template
? jp main
? jp __start
}
asm void clear_ram() {
? xor a
? ld hl,$c000
? ld bc,$1ff0
? call memset
? ld hl,$8000
? ld bc,$2000
? call memset
? ld hl,$fe00
? ld bc,$a0
? call memset
? ld hl,$ff80
? ld bc,$7f
? call memset
? ret
}
inline asm void memset(word hl, word bc) {
? inc c
? inc b
? jr __memzero_start
__memzero_loop:
ld (hli), a
__memzero_start:
dec c
jr nz, __memzero_loop
dec b
jr nz, __memzero_loop
? ret
}
interrupt void __on_vblank(){
on_vblank()
}
interrupt void __on_lcdc(){
on_lcdc()
}
interrupt void __on_timer(){
on_timer()
}
interrupt void __on_serial(){
on_serial()
}
interrupt void __on_joypad(){
on_joypad()
}
// TODO: optimize?
const array __vectors @ $40 = [
$c3, __on_vblank.addr.lo, __on_vblank.addr.hi, 0,0,0,0,0,
$c3, __on_lcdc.addr.lo, __on_lcdc.addr.hi, 0,0,0,0,0,
$c3, __on_timer.addr.lo, __on_timer.addr.hi, 0,0,0,0,0,
$c3, __on_serial.addr.lo, __on_serial.addr.hi, 0,0,0,0,0,
$c3, __on_joypad.addr.lo, __on_joypad.addr.hi, 0,0,0,0,0
]
array oam[$a0] @$fe00
volatile byte reg_joypad @$ff00
volatile byte reg_irq_flag @$ff0f
volatile byte reg_lcd_ctrl @$ff40
volatile byte reg_lcd_status @$ff41
volatile byte reg_scroll_y @$ff42
volatile byte reg_scroll_x @$ff43
volatile byte reg_dma @$ff46
volatile byte reg_bg_palette @$ff47
volatile byte reg_obj0_palette @$ff48
volatile byte reg_obj1_palette @$ff49
volatile byte reg_window_y @$ff4A
volatile byte reg_window_x @$ff4B
volatile byte reg_vram_bank @$ff4f
volatile byte reg_irq_enable @$ffff
const byte lcd_on = $80
const byte lcd_off = 0
const byte lcd_win_9c00 = $40
const byte lcd_win_9800 = 0
const byte lcd_win_on = $20
const byte lcd_win_off = 0
const byte lcd_tile_8000 = $10
const byte lcd_tile_8800 = 0
const byte lcd_map_9c00 = 8
const byte lcd_map_9800 = 0
const byte lcd_obj_16 = 4
const byte lcd_obj_8 = 0
const byte lcd_obj_on = 2
const byte lcd_obj_off = 0
const byte lcd_bg_on = 1
const byte lcd_bg_off = 1
const byte ief_vblank = 1
segment(hiram)
array __sprite_dma_actual[8]
asm void __sprite_dma_template() {
ldh (reg_dma),a
ld a, $28
__sprite_dma_wait:
dec a
jr nz, __sprite_dma_wait
ret
__sprite_dma_end:
}
asm void sprite_dma(byte a) {
jp __sprite_dma_actual
}
asm byte wait_for_vblank() {
ld hl, reg_irq_flag
__wait_for_vblank_loop:
ld a, ief_vblank
halt
and (hl)
jr z, __wait_for_vblank_loop
? ld a, $ff ^ ief_vblank
? and (hl)
? ret
}
asm void disable_lcd() {
? call wait_for_vblank
ldh a,(reg_lcd_ctrl)
res 7,a
ldh (reg_lcd_ctrl),a
? ret
}
asm void enable_lcd() {
? call wait_for_vblank
ldh a,(reg_lcd_ctrl)
set 7,a
ldh (reg_lcd_ctrl),a
? ret
}