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cc65/libsrc/apple2/crt0.s
cuz f3b93741ab Use the condes feature
git-svn-id: svn://svn.cc65.org/cc65/trunk@470 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-11-22 22:19:09 +00:00

122 lines
2.2 KiB
ArmAsm

;
; Startup code for cc65 (Apple2 version)
;
; This must be the *first* file on the linker command line
;
.export _exit
.import initlib, donelib
.import zerobss, push0
.import _main
.include "apple2.inc"
; ------------------------------------------------------------------------
; Define and export the ZP variables for the C64 runtime
.exportzp sp, sreg, regsave
.exportzp ptr1, ptr2, ptr3, ptr4
.exportzp tmp1, tmp2, tmp3, tmp4
.exportzp regbank, zpspace
; These zero page entries overlap with the sweet-16 registers in
; the standard apple2 linker config. They must be changed if sweet-16
; is to be supported
.zeropage
zpstart = *
sp: .res 2 ; Stack pointer
sreg: .res 2 ; Secondary register/high 16 bit for longs
regsave: .res 2 ; slot to save/restore (E)AX into
ptr1: .res 2
ptr2: .res 2
ptr3: .res 2
ptr4: .res 2
tmp1: .res 1
tmp2: .res 1
tmp3: .res 1
tmp4: .res 1
regbank: .res 6 ; 6 byte register bank
zpspace = * - zpstart ; Zero page space allocated
.code
; ------------------------------------------------------------------------
; Actual code
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x ; Save the zero page locations we need
dex
bpl L1
; Clear the BSS data
jsr zerobss
; Save system stuff and setup the stack
tsx
stx spsave ; Save the system stack ptr
lda #<TOPMEM
sta sp
lda #>TOPMEM
sta sp+1 ; Set argument stack ptr
; Call module constructors
jsr initlib
; Initialize conio stuff
lda #$ff
sta TEXTTYP
; Set up to use Apple ROM $C000-$CFFF
;; sta USEROM
; Pass an empty command line
jsr push0 ; argc
jsr push0 ; argv
ldy #4 ; Argument size
jsr _main ; call the users code
; Call module destructors. This is also the _exit entry.
_exit: jsr donelib
; Restore system stuff
lda #$ff ; Reset text mode
sta TEXTTYP
ldx spsave
txs ; Restore stack pointer
; Copy back the zero page stuff
ldx #zpspace-1
L2: lda zpsave,x
sta sp,x
dex
bpl L2
; Reset changed vectors, back to basic
jmp RESTOR
.data
zpsave: .res zpspace
.bss
spsave: .res 1