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cc65/libsrc/atmos/crt0.s
uz 8216bf1d6a Force an import of the special symbol __STARTUP__ in the C compiler when
main() is encountered. Define this symbol in the startup code. This will
automatically force linking of the startup code which can then reside inside
the standard library as any other object file.


git-svn-id: svn://svn.cc65.org/cc65/trunk@3988 b7a2c559-68d2-44c3-8de9-860c34a00d81
2009-07-31 12:05:42 +00:00

111 lines
2.4 KiB
ArmAsm

;
; Startup code for cc65 (Oric version)
;
; By Debrune Jérôme <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__, __BSS_LOAD__
.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 __BSS_LOAD__ ; $2AB
.dbyt __RAM_START__ ; $2A9
.byte $00 ; $2A8
.byte $00 ; Zero terminated name
; ------------------------------------------------------------------------
; 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__)
sta sp
lda #>(__RAM_START__ + __RAM_SIZE__)
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
; ------------------------------------------------------------------------
; Data
.segment "ZPSAVE"
zpsave: .res zpspace
.bss
spsave: .res 1
stsave: .res 1