crt0.s

; Startup code for cc65 and Shiru's NES library
; based on code by Groepaz/Hitmen <groepaz@gmx.net>, Ullrich von Bassewitz <uz@cc65.org>


FT_DPCM_OFF				= $c000		;$c000..$ffc0, 64-byte steps
FT_SFX_STREAMS			= 4			;number of sound effects played at once, 1..4

.define FT_DPCM_ENABLE  1			;undefine to exclude all DMC code
.define FT_SFX_ENABLE   1			;undefine to exclude all sound effects code



    .export _exit,__STARTUP__:absolute=1
	.import initlib,push0,popa,popax,_main,zerobss,copydata

; Linker generated symbols
	.import __RAM_START__   ,__RAM_SIZE__
	.import __ROM0_START__  ,__ROM0_SIZE__
	.import __STARTUP_LOAD__,__STARTUP_RUN__,__STARTUP_SIZE__
	.import	__CODE_LOAD__   ,__CODE_RUN__   ,__CODE_SIZE__
	.import	__RODATA_LOAD__ ,__RODATA_RUN__ ,__RODATA_SIZE__
	.import NES_MAPPER,NES_PRG_BANKS,NES_CHR_BANKS,NES_MIRRORING
    .include "zeropage.inc"



FT_BASE_ADR		=$0100	;page in RAM, should be $xx00

.define FT_THREAD       1	;undefine if you call sound effects in the same thread as sound update
.define FT_PAL_SUPPORT	1   ;undefine to exclude PAL support
.define FT_NTSC_SUPPORT	1   ;undefine to exclude NTSC support


PPU_CTRL	=$2000
PPU_MASK	=$2001
PPU_STATUS	=$2002
PPU_OAM_ADDR=$2003
PPU_OAM_DATA=$2004
PPU_SCROLL	=$2005
PPU_ADDR	=$2006
PPU_DATA	=$2007
PPU_OAM_DMA	=$4014
PPU_FRAMECNT=$4017
DMC_FREQ	=$4010
CTRL_PORT1	=$4016
CTRL_PORT2	=$4017

OAM_BUF		=$0200
PAL_BUF		=$01c0



.segment "ZEROPAGE"

NTSC_MODE: 			.res 1
FRAME_CNT1: 		.res 1
FRAME_CNT2: 		.res 1
VRAM_UPDATE: 		.res 1
NAME_UPD_ADR: 		.res 2
NAME_UPD_ENABLE: 	.res 1
PAL_UPDATE: 		.res 1
PAL_BG_PTR: 		.res 2
PAL_SPR_PTR: 		.res 2
SCROLL_X: 			.res 1
SCROLL_Y: 			.res 1
SCROLL_X1: 			.res 1
SCROLL_Y1: 			.res 1
PAD_STATE: 			.res 2		;one byte per controller
PAD_STATEP: 		.res 2
PAD_STATET: 		.res 2
PPU_CTRL_VAR: 		.res 1
PPU_CTRL_VAR1: 		.res 1
PPU_MASK_VAR: 		.res 1
RAND_SEED: 			.res 2
FT_TEMP: 			.res 3

TEMP: 				.res 11

PAD_BUF		=TEMP+1

PTR			=TEMP	;word
LEN			=TEMP+2	;word
NEXTSPR		=TEMP+4
SCRX		=TEMP+5
SCRY		=TEMP+6
SRC			=TEMP+7	;word
DST			=TEMP+9	;word

RLE_LOW		=TEMP
RLE_HIGH	=TEMP+1
RLE_TAG		=TEMP+2
RLE_BYTE	=TEMP+3



.segment "HEADER"

    .byte $4e,$45,$53,$1a
	.byte <NES_PRG_BANKS
	.byte <NES_CHR_BANKS
	.byte <NES_MIRRORING|(<NES_MAPPER<<4)
	.byte <NES_MAPPER&$f0
	.res 8,0



.segment "STARTUP"

start:
_exit:

    sei
    ldx #$ff
    txs
    inx
    stx PPU_MASK
    stx DMC_FREQ
    stx PPU_CTRL		;no NMI

initPPU:
    bit PPU_STATUS
@1:
    bit PPU_STATUS
    bpl @1
@2:
    bit PPU_STATUS
    bpl @2

clearPalette:
	lda #$3f
	sta PPU_ADDR
	stx PPU_ADDR
	lda #$0f
	ldx #$20
@1:
	sta PPU_DATA
	dex
	bne @1

clearVRAM:
	txa
	ldy #$20
	sty PPU_ADDR
	sta PPU_ADDR
	ldy #$10
@1:
	sta PPU_DATA
	inx
	bne @1
	dey
	bne @1

clearRAM:
    txa
@1:
    sta $000,x
    sta $100,x
    sta $200,x
    sta $300,x
    sta $400,x
    sta $500,x
    sta $600,x
    sta $700,x
    inx
    bne @1

	lda #4
	jsr _pal_bright
	jsr _pal_clear
	jsr _oam_clear

    jsr	zerobss
	jsr	copydata

    lda #<(__RAM_START__+__RAM_SIZE__)
    sta	sp
    lda	#>(__RAM_START__+__RAM_SIZE__)
    sta	sp+1            ; Set argument stack ptr

	jsr	initlib

	lda #%10000000
	sta <PPU_CTRL_VAR
	sta PPU_CTRL		;enable NMI
	lda #%00000110
	sta <PPU_MASK_VAR

waitSync3:
	lda <FRAME_CNT1
@1:
	cmp <FRAME_CNT1
	beq @1

detectNTSC:
	ldx #52				;blargg's code
	ldy #24
@1:
	dex
	bne @1
	dey
	bne @1

	lda PPU_STATUS
	and #$80
	sta <NTSC_MODE

	jsr _ppu_off

	lda #0
	ldx #0
	jsr _set_vram_update

	ldx #<music_data
	ldy #>music_data
	lda <NTSC_MODE
	jsr FamiToneInit

	.if(FT_SFX_ENABLE)
	ldx #<sounds_data
	ldy #>sounds_data
	jsr FamiToneSfxInit
	.endif

	lda #$fd
	sta <RAND_SEED
	sta <RAND_SEED+1

	lda #0
	sta PPU_SCROLL
	sta PPU_SCROLL

	jmp _main			;no parameters

	.include "neslib.s"

.segment "RODATA"

music_data:
	.include "music.s"

	.if(FT_SFX_ENABLE)
sounds_data:
	.include "sounds.s"
	.endif

.segment "SAMPLES"

	;.incbin "music_dpcm.bin"

.segment "VECTORS"

    .word nmi	;$fffa vblank nmi
    .word start	;$fffc reset
   	.word irq	;$fffe irq / brk


.segment "CHARS"

	.incbin "tileset.chr"