209 lines
3.4 KiB
ArmAsm
209 lines
3.4 KiB
ArmAsm
; Startup code for cc65 and Shiru's NES library
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; based on code by Groepaz/Hitmen <groepaz@gmx.net>, Ullrich von Bassewitz <uz@cc65.org>
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; edited by Steven Hugg (remove integrated Famitone2 library, add NMICallback)
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.export _exit,__STARTUP__:absolute=1
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.import initlib,push0,popa,popax,_main,zerobss,copydata
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; Linker generated symbols
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.import __RAM_START__ ,__RAM_SIZE__
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.import __ROM0_START__ ,__ROM0_SIZE__
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.import __STARTUP_LOAD__,__STARTUP_RUN__,__STARTUP_SIZE__
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.import __CODE_LOAD__ ,__CODE_RUN__ ,__CODE_SIZE__
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.import __RODATA_LOAD__ ,__RODATA_RUN__ ,__RODATA_SIZE__
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.import NES_MAPPER,NES_PRG_BANKS,NES_CHR_BANKS,NES_MIRRORING
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.include "zeropage.inc"
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.include "nes.inc"
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FT_BASE_ADR =$0100 ;page in RAM, should be $xx00
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.define FT_THREAD 1 ;undefine if you call sound effects in the same thread as sound update
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.define FT_PAL_SUPPORT 1 ;undefine to exclude PAL support
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.define FT_NTSC_SUPPORT 1 ;undefine to exclude NTSC support
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.segment "ZEROPAGE"
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NTSC_MODE: .res 1
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FRAME_CNT1: .res 1
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FRAME_CNT2: .res 1
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VRAM_UPDATE: .res 1
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NAME_UPD_ADR: .res 2
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NAME_UPD_ENABLE: .res 1
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PAL_UPDATE: .res 1
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PAL_BG_PTR: .res 2
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PAL_SPR_PTR: .res 2
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SCROLL_X: .res 1
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SCROLL_Y: .res 1
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SCROLL_X1: .res 1
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SCROLL_Y1: .res 1
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PPU_CTRL_VAR: .res 1
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PPU_CTRL_VAR1: .res 1
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PPU_MASK_VAR: .res 1
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;;FT_TEMP: .res 3
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_oam_off: .res 1
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NMICallback: .res 3
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TEMP: .res 11
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.exportzp NTSC_MODE, FRAME_CNT1, FRAME_CNT2, VRAM_UPDATE
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.exportzp NAME_UPD_ADR, NAME_UPD_ENABLE
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.exportzp PAL_UPDATE, PAL_BG_PTR, PAL_SPR_PTR
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.exportzp SCROLL_X, SCROLL_Y, SCROLL_X1, SCROLL_Y1
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.exportzp PPU_CTRL_VAR, PPU_CTRL_VAR1, PPU_MASK_VAR
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.exportzp _oam_off, NMICallback
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.exportzp TEMP
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.include "zpvars.inc"
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.segment "HEADER"
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.byte $4e,$45,$53,$1a
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.byte <NES_PRG_BANKS
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.byte <NES_CHR_BANKS
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.byte <NES_MIRRORING|(<NES_MAPPER<<4)
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.byte <NES_MAPPER&$f0
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.res 8,0
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.segment "STARTUP"
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start:
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_exit:
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sei
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ldx #$ff
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txs
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inx
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stx PPU_MASK
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stx DMC_FREQ
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stx PPU_CTRL ;no NMI
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initPPU:
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bit PPU_STATUS
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@1:
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bit PPU_STATUS
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bpl @1
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@2:
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bit PPU_STATUS
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bpl @2
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; no APU frame counter IRQs
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lda #$40
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sta PPU_FRAMECNT
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clearPalette:
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lda #$3f
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sta PPU_ADDR
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stx PPU_ADDR
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lda #$0f
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ldx #$20
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@1:
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sta PPU_DATA
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dex
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bne @1
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clearVRAM:
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txa
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ldy #$20
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sty PPU_ADDR
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sta PPU_ADDR
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ldy #$10
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@1:
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sta PPU_DATA
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inx
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bne @1
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dey
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bne @1
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clearRAM:
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txa
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@1:
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sta $000,x
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sta $100,x
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sta $200,x
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sta $300,x
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sta $400,x
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sta $500,x
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sta $600,x
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sta $700,x
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inx
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bne @1
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lda #4
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jsr _pal_bright
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jsr _pal_clear
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jsr _oam_clear
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jsr zerobss
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jsr copydata
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lda #<(__RAM_START__+__RAM_SIZE__)
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sta sp
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lda #>(__RAM_START__+__RAM_SIZE__)
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sta sp+1 ; Set argument stack ptr
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jsr initlib
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; setup NMICallback trampoline to NOP
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lda #$4C ;JMP xxxx
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sta NMICallback
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lda #<HandyRTS
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sta NMICallback+1
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lda #>HandyRTS
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sta NMICallback+2
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lda #%10000000
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sta <PPU_CTRL_VAR
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sta PPU_CTRL ;enable NMI
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lda #%00000110
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sta <PPU_MASK_VAR
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waitSync3:
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lda <FRAME_CNT1
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@1:
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cmp <FRAME_CNT1
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beq @1
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detectNTSC:
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ldx #52 ;blargg's code
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ldy #24
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@1:
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dex
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bne @1
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dey
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bne @1
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lda PPU_STATUS
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and #$80
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sta <NTSC_MODE
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jsr _ppu_off
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lda #0
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sta PPU_SCROLL
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sta PPU_SCROLL
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sta PPU_OAM_ADDR
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jmp _main ;no parameters
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.include "neslib.sinc"
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.segment "CHARS"
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;;
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.segment "SAMPLES"
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;;
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.segment "VECTORS"
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.word nmi ;$fffa vblank nmi
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.word start ;$fffc reset
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.word irq ;$fffe irq / brk
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