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cc65/libsrc/lynx/crt0.s
2020-04-02 10:42:06 +02:00

136 lines
3.1 KiB
ArmAsm

; ***
; CC65 Lynx Library
;
; Originally by Bastian Schick
; http://www.geocities.com/SiliconValley/Byte/4242/lynx/
;
; Ported to cc65 (http://www.cc65.org) by
; Shawn Jefferson, June 2004
;
; ***
;
; Startup code for cc65 (Lynx version). Based on the Atari 8-bit startup
; code structure. The C stack is located at the end of the RAM memory
; segment, and grows downward. Bastian Schick's executable header is put
; on the front of the fully linked binary (see EXEHDR segment.)
;
.export _exit
.export __STARTUP__ : absolute = 1 ; Mark as startup
.import initlib, donelib
.import zerobss
.import callmain
.import _main
.import __MAIN_START__, __MAIN_SIZE__, __STACKSIZE__
.include "zeropage.inc"
.include "extzp.inc"
.include "lynx.inc"
; ------------------------------------------------------------------------
; Mikey and Suzy init data, reg offsets and data
.rodata
SuzyInitReg: .byte $28,$2a,$04,$06,$92,$83,$90
SuzyInitData: .byte $7f,$7f,$00,$00,$24,$f3,$01
MikeyInitReg: .byte $00,$01,$08,$09,$20,$28,$30,$38,$44,$50,$8a,$8b,$8c,$92,$93
MikeyInitData: .byte $9e,$18,$68,$1f,$00,$00,$00,$00,$00,$ff,$1a,$1b,$04,$0d,$29
; ------------------------------------------------------------------------
; Actual code
.segment "STARTUP"
; Set up the system.
sei
ldx #$FF
txs
; Init the bank switching.
lda #$C
sta MAPCTL ; $FFF9
; Disable all timer interrupts.
lda #$80
trb TIM0CTLA
trb TIM1CTLA
trb TIM2CTLA
trb TIM3CTLA
trb TIM5CTLA
trb TIM6CTLA
trb TIM7CTLA
; Disable the TX/RX IRQ; set to 8E1.
lda #%00011101
sta SERCTL
; Clear all pending interrupts.
lda INTSET
sta INTRST
; Set up the stack.
lda #<(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
ldx #>(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
sta sp
stx sp+1
; Init Mickey.
ldx #.sizeof(MikeyInitReg)-1
mloop: ldy MikeyInitReg,x
lda MikeyInitData,x
sta $fd00,y
dex
bpl mloop
; These are RAM-shadows of read-only regs.
ldx #$1b
stx __iodat
dex ; $1A
stx __iodir
ldx #$d
stx __viddma
; Init Suzy.
ldx #.sizeof(SuzyInitReg)-1
sloop: ldy SuzyInitReg,x
lda SuzyInitData,x
sta $fc00,y
dex
bpl sloop
lda #$24
sta __sprsys
cli
; Clear the BSS data.
jsr zerobss
; Call the module constructors.
jsr initlib
; Push the command-line arguments; and, call main().
jsr callmain
; Call the module destructors. This is also the exit() entry.
_exit: jsr donelib ; Run module destructors
; Endless loop
noret: bra noret