cc65/libsrc/geos-common/system/crt0.s

;
; Startup code for geos
;
; Maciej 'YTM/Elysium' Witkowiak
; 26.10.99, 10.3.2000, 15.8.2001, 23.12.2002

	    .export _exit
	    .export __STARTUP__ : absolute = 1		; Mark as startup
	    .import __STACKADDR__, __STACKSIZE__	; Linker generated
	    .import __BACKBUFSIZE__			; Linker generated
	    .import initlib, donelib
	    .import callmain
	    .import zerobss
	    .importzp sp

	    .include "jumptab.inc"
	    .include "geossym.inc"
	    .include "const.inc"

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

.segment	"STARTUP"

; GEOS 64/128 initializes the screen before starting an application while
; Apple GEOS does not. In order to provide identical startup conditions
; we initialize the screen here on Apple GEOS. For the same reason we set
; the pattern and dispBufferOn even on GEOS 64/128 although we don't use
; them here.

	lda #2			; Checkerboard pattern
	jsr SetPattern
	lda #<(ST_WR_FORE | .MIN (ST_WR_BACK, __BACKBUFSIZE__))
	sta dispBufferOn
.ifdef __GEOS_APPLE__
	jsr i_Rectangle
	.byte 0
	.byte SC_PIX_HEIGHT-1
	.word 0
	.word SC_PIX_WIDTH-1
.endif

; Clear the BSS data.

	jsr zerobss

; Setup stack.

	lda #<(__STACKADDR__ + __STACKSIZE__)
	ldx #>(__STACKADDR__ + __STACKSIZE__)
	sta sp
	stx sp+1

; Call module constructors.

	jsr initlib

; Push arguments and call main().

	cli
	jsr callmain

; Call module destructors.

_exit:	jsr donelib

	jmp EnterDeskTop	; Return control to the system