cc65/libsrc/atmos/crt0.s

;
; Startup code for cc65 (Oric version)
;
; By Debrune J<>r<EFBFBD>me <jede@oric.org> and Ullrich von Bassewitz <uz@cc65.org>
;

        .export         _exit
        .export         __STARTUP__ : absolute = 1      ; Mark as startup
        .import         initlib, donelib
        .import         callmain, zerobss
        .import         __RAM_START__, __RAM_SIZE__
        .import         __ZPSAVE_LOAD__, __STACKSIZE__

        .include        "zeropage.inc"
        .include        "atmos.inc"

; ------------------------------------------------------------------------
; Oric tape header

.segment        "TAPEHDR"

        .byte   $16, $16, $16   ; Sync bytes
        .byte   $24             ; End of header marker

        .byte   $00                             ; $2B0
        .byte   $00                             ; $2AF
        .byte   $80                             ; $2AE Machine code flag
        .byte   $C7                             ; $2AD Autoload flag
        .dbyt   __ZPSAVE_LOAD__ - 1             ; $2AB
        .dbyt   __RAM_START__                   ; $2A9
        .byte   $00                             ; $2A8
        .byte   ((.VERSION >> 8) & $0F) + '0'
        .byte   ((.VERSION >> 4) & $0F) + '0'
        .byte   (.VERSION & $0F) + '0'
        .byte   $00                             ; Zero terminated compiler version

; ------------------------------------------------------------------------
; Place the startup code in a special segment.

.segment        "STARTUP"

; Save the zero page area we're about to use

        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

; Unprotect columns 0 and 1

        lda     STATUS
        sta     stsave
        and     #%11011111
        sta     STATUS

; Save system stuff and setup the stack

        tsx
        stx     spsave          ; Save system stk ptr

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

; Call module constructors

        jsr     initlib

; Push arguments and call main()

        jsr     callmain

; Call module destructors. This is also the _exit entry.

_exit:  jsr     donelib         ; Run module destructors

; Restore system stuff

        ldx     spsave
        txs
        lda     stsave
        sta     STATUS

; Copy back the zero page stuff

        ldx     #zpspace-1
L2:     lda     zpsave,x
        sta     sp,x
        dex
        bpl     L2

; Back to BASIC

        rts

; ------------------------------------------------------------------------

.segment        "ZPSAVE"

zpsave: .res    zpspace

; ------------------------------------------------------------------------

.bss

spsave: .res    1
stsave: .res    1