nuclear@0: ; vi:ft=rgbasm:
nuclear@4: ; -------- build options ----------
nuclear@4: BUILD_CHESS equ 1
nuclear@4: BUILD_LOGO equ 2
nuclear@4: 
nuclear@4: BUILD = BUILD_LOGO
nuclear@4: ; ---------------------------------
nuclear@4: 
nuclear@0: include "hw.inc"
nuclear@0: 
nuclear@0: xoffs_center equ 4
nuclear@0: yoffs_center equ 12
nuclear@0: 
nuclear@3: frame equ $ff80
nuclear@3: bnstate equ $ff81
nuclear@3: bnxor equ $ff82
nuclear@3: pause equ $ff83
nuclear@3: 
nuclear@3: BN_A		equ $01
nuclear@3: BN_B		equ $02
nuclear@3: BN_SELECT	equ $04
nuclear@3: BN_START	equ $08
nuclear@3: BN_RIGHT	equ $10
nuclear@3: BN_LEFT		equ $20
nuclear@3: BN_UP		equ $40
nuclear@3: BN_DOWN		equ $80
nuclear@0: 
nuclear@0: section "hdr", ROM0[$100]
nuclear@0:         nop
nuclear@0:         jp main
nuclear@0: 
nuclear@0: rept $150 - $104
nuclear@0:         db 0
nuclear@0: endr
nuclear@0: 
nuclear@0: section "text", ROM0
nuclear@0: 
nuclear@0: main:
nuclear@0: 	call init
nuclear@0: 
nuclear@0: 	xor a, a
nuclear@3: 	ldh [frame], a
nuclear@3: 	ldh [bnstate], a
nuclear@3: 	ldh [bnxor], a
nuclear@3: 	ldh [pause], a
nuclear@3: 
nuclear@0: .mainloop:
nuclear@0: 	ldh a, [REG_LY]
nuclear@0: 	cp a, 144
nuclear@0: 	jr c, .wait_hsync
nuclear@0: 
nuclear@3: 	; we're in vsync, increment frame counter, handle input,
nuclear@3: 	; and wait for the next frame
nuclear@3: 	call read_input
nuclear@3: 
nuclear@3: 	; swap palette if A is pressed
nuclear@3: 	ldh a, [bnxor]
nuclear@3: 	and a, BN_A
nuclear@3: 	jr z, .skip_akey  ; skip if A haven't changed state since last frame
nuclear@3: 	ldh a, [bnstate]
nuclear@3: 	and a, BN_A
nuclear@3: 	jr z, .skip_akey  ; skip if A is not pressed
nuclear@3: 	ldh a, [REG_BGP]
nuclear@3: 	cpl
nuclear@3: 	ldh [REG_BGP], a
nuclear@3: .skip_akey:
nuclear@3: 	; toggle pause if start is pressed
nuclear@3: 	ldh a, [bnxor]
nuclear@3: 	and a, BN_START
nuclear@3: 	jr z, .skip_startkey ; skip if start haven't changed state since last frame
nuclear@3: 	ldh a, [bnstate]
nuclear@3: 	and a, BN_START
nuclear@3: 	jr z, .skip_startkey ; skip if start is not pressed
nuclear@3: 	ldh a, [pause]
nuclear@3: 	cpl
nuclear@3: 	ldh [pause], a
nuclear@3: .skip_startkey:
nuclear@3: 
nuclear@3: 	; increment frame if we're not paused
nuclear@3: 	ldh a, [pause]
nuclear@3: 	bit 0, a
nuclear@3: 	jr nz, .skip_frameinc
nuclear@3: 	ldh a, [frame]
nuclear@0: 	inc a
nuclear@3: 	ldh [frame], a
nuclear@3: .skip_frameinc:
nuclear@3: 
nuclear@3: 
nuclear@0: .wait_newframe:
nuclear@0: 	ldh a, [REG_LY]
nuclear@0: 	cp a, 0
nuclear@0: 	jr nz, .wait_newframe
nuclear@0: 
nuclear@0: 	; scanline code
nuclear@0: .wait_hsync:
nuclear@0: 	ldh a, [REG_STAT]
nuclear@0: 	and a, STAT_MODE_MASK
nuclear@0: 	jr nz, .wait_hsync
nuclear@0: 
nuclear@3: 	ldh a, [frame]
nuclear@0: 	ld d, a
nuclear@0: 
nuclear@0: 	xor a, a
nuclear@0: 	ld b, a
nuclear@1: 
nuclear@0: 	ldh a, [REG_LY]
nuclear@1: 	add a, d	; add frame number
nuclear@0: 	ld c, a
nuclear@0: 
nuclear@0: 	ld hl, sintab
nuclear@1: 	add hl, bc	; hl now points to the sine value
nuclear@0: 
nuclear@1: 	ld a, [hl]
nuclear@1: 
nuclear@1: 	; add a half-octave sine
nuclear@1: 	ld e, a		; save first sine to e
nuclear@1: 	sla d
nuclear@1: 	ld a, [REG_LY]
nuclear@1: 	sla a
nuclear@1: 	add a, d
nuclear@1: 	ld c, a
nuclear@1: 	srl d
nuclear@1: 
nuclear@1: 	ld hl, sintab
nuclear@1: 	add hl, bc
nuclear@1: 	ld a, [hl]
nuclear@1: 	sra a
nuclear@1: 	add a, e	; add previously saved sine
nuclear@1: 
nuclear@1: 	add a, yoffs_center
nuclear@0: 	ldh [REG_SCY], a
nuclear@0: 
nuclear@1: 	; do something for SCX too
nuclear@1: 	ld a, d
nuclear@1: 	sla a
nuclear@1: 	ld d, a
nuclear@1: 
nuclear@1: 	ldh a, [REG_LY]
nuclear@1: 	add a, 32
nuclear@1: 	add a, d	; add frame number
nuclear@1: 	ld c, a
nuclear@1: 
nuclear@1: 	ld hl, sintab
nuclear@1: 	add hl, bc
nuclear@1: 
nuclear@1: 	ld a, [hl]
nuclear@1: 	sra a
nuclear@1: 	add a, xoffs_center
nuclear@1: 	ldh [REG_SCX], a
nuclear@1: 
nuclear@0: 	; done, wait until we're out of hsync
nuclear@0: .wait_endhsync:
nuclear@0: 	ldh a, [REG_STAT]
nuclear@0: 	and a, STAT_MODE_MASK
nuclear@0: 	jr z, .wait_endhsync
nuclear@0: 
nuclear@3: 	jp .mainloop 
nuclear@0: 
nuclear@0: 
nuclear@0: 	di
nuclear@0: .end:   halt
nuclear@0:         nop
nuclear@0:         jp .end
nuclear@0: 
nuclear@0: init:
nuclear@0: 	call wait_vsync
nuclear@0: 	xor a, a
nuclear@0: 	ldh [REG_LCDC], a
nuclear@0: 
nuclear@2: 	; setup palette
nuclear@0: 	ld a, $1b
nuclear@0: 	ldh [REG_BGP], a
nuclear@0: 
nuclear@0: 	; copy tiles
nuclear@0: 	ld hl, $8000
nuclear@0: 	ld de, tiles
nuclear@0: 	ld bc, tiles_end - tiles
nuclear@0: .copytiles:
nuclear@0: 	ld a, [de]
nuclear@0: 	ld [hl+], a
nuclear@0: 	inc de
nuclear@0: 	dec bc
nuclear@0: 	ld a, b
nuclear@0: 	or c
nuclear@0: 	jp nz, .copytiles
nuclear@0: 
nuclear@4: IF BUILD == BUILD_LOGO
nuclear@4: 	; copy logo tilemap
nuclear@0: 	ld hl, $9800
nuclear@0: 	ld de, tilemap
nuclear@0: 	ld b, 21
nuclear@0: .copymap:
nuclear@0: 	ld c, 21
nuclear@0: .copymaprow:
nuclear@0: 	ld a, [de]
nuclear@0: 	inc de
nuclear@0: 	ld [hl+], a
nuclear@0: 	dec c
nuclear@0: 	jr nz, .copymaprow
nuclear@0: 
nuclear@0: 	push bc
nuclear@0: 	ld bc, 11
nuclear@0: 	add hl, bc
nuclear@0: 	pop bc
nuclear@0: 
nuclear@0: 	dec b
nuclear@0: 	jr nz, .copymap
nuclear@4: ELSE
nuclear@4: 	; generate chessboard tilemap
nuclear@4: 	ld hl, $9800
nuclear@4: 	ld b, 32
nuclear@4: .fillscr:
nuclear@4: 	ld c, 32
nuclear@4: .fillrow:
nuclear@4: 	ld a, b
nuclear@4: 	add a, c
nuclear@4: 	and a, 1
nuclear@4: 
nuclear@4: 	ld [hl+], a
nuclear@4: 	dec c
nuclear@4: 	jr nz, .fillrow
nuclear@4: 
nuclear@4: 	dec b
nuclear@4: 	jr nz, .fillscr
nuclear@4: ENDC
nuclear@0: 
nuclear@0: 	; center viewport
nuclear@0: 	ld a, yoffs_center
nuclear@0: 	ldh [REG_SCY], a
nuclear@0: 	ld a, xoffs_center
nuclear@0: 	ldh [REG_SCX], a
nuclear@0: 
nuclear@0: 	; configure LCD
nuclear@0: 	ld a, LCDC_DISPON | LCDC_CHAR_8000 | LCDC_BGON
nuclear@0: 	ldh [REG_LCDC], a
nuclear@0: 	ret
nuclear@0: 
nuclear@0: wait_vsync:
nuclear@0: 	ldh a, [REG_LY]
nuclear@0: 	cp a, 144
nuclear@0: 	jr c, wait_vsync
nuclear@0: 	ret
nuclear@0: 
nuclear@3: read_input:
nuclear@3: 	; read D-pad
nuclear@3: 	ld a, P1_DPAD
nuclear@3: 	ld [REG_P1], a
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	cpl
nuclear@3: 	and a, $0f
nuclear@3: 	swap a
nuclear@3: 	ld b, a
nuclear@3: 	; read buttons
nuclear@3: 	ld a, P1_BUTTONS
nuclear@3: 	ld [REG_P1], a
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	ld a, [REG_P1]
nuclear@3: 	cpl
nuclear@3: 	and a, $0f
nuclear@3: 	or a, b
nuclear@3: 	ld b, a
nuclear@3: 	; reset port
nuclear@3: 	ld a, P1_DPAD | P1_BUTTONS
nuclear@3: 	ldh [REG_P1], a
nuclear@3: 	; calculate differences and save state variables
nuclear@3: 	ldh a, [bnstate]
nuclear@3: 	xor a, b
nuclear@3: 	ldh [bnxor], a
nuclear@3: 	ld a, b
nuclear@3: 	ldh [bnstate], a
nuclear@3: 	ret
nuclear@3: 
nuclear@0: section "data", ROM0, align[8]
nuclear@0: sintab:
nuclear@0: include "sin.inc"
nuclear@0: 
nuclear@4: IF BUILD == BUILD_LOGO
nuclear@0: tiles:
nuclear@0: incbin "logo.tiles"
nuclear@0: tiles_end:
nuclear@0: tilemap:
nuclear@0: incbin "logo.tilemap"
nuclear@0: tilemap_end:
nuclear@4: 
nuclear@4: ELSE
nuclear@4: ; chessboard tiles
nuclear@4: tiles:
nuclear@4: 	db $55,$00
nuclear@4: 	db $aa,$00
nuclear@4: 	db $55,$00
nuclear@4: 	db $aa,$00
nuclear@4: 	db $55,$00
nuclear@4: 	db $aa,$00
nuclear@4: 	db $55,$00
nuclear@4: 	db $aa,$00
nuclear@4: 
nuclear@4: 	db $ff,$aa
nuclear@4: 	db $ff,$55
nuclear@4: 	db $ff,$aa
nuclear@4: 	db $ff,$55
nuclear@4: 	db $ff,$aa
nuclear@4: 	db $ff,$55
nuclear@4: 	db $ff,$aa
nuclear@4: 	db $ff,$55
nuclear@4: tiles_end:
nuclear@4: ENDC