cc65/libsrc/runtime/condes.s

;
; Ullrich von Bassewitz, 20.11.2000
;
; CC65 runtime: Support for calling module constructors/destructors
;
; The condes routine must be called with the table address in a/x and the
; size of the table (which must not be zero!) in y. The current implementation
; limits the table size to 254 bytes (127 vectors) but this shouldn't be
; problem for now and may be changed later.
;
; libinit and libdone call condes with the predefined module constructor and
; destructor tables, they must be called from the platform specific startup
; code.


       	.export	initlib, donelib, condes

       	.import	__CONSTRUCTOR_TABLE__, __CONSTRUCTOR_COUNT__
	.import	__DESTRUCTOR_TABLE__, __DESTRUCTOR_COUNT__

        .macpack        cpu

.code

; --------------------------------------------------------------------------
; Initialize library modules

.proc	initlib

	ldy    	#<(__CONSTRUCTOR_COUNT__*2)
       	beq    	exit
	lda    	#<__CONSTRUCTOR_TABLE__
	ldx    	#>__CONSTRUCTOR_TABLE__
        jmp     condes
exit:   rts

.endproc


; --------------------------------------------------------------------------
; Cleanup library modules

.proc	donelib

    	ldy 	#<(__DESTRUCTOR_COUNT__*2)
    	beq     initlib::exit
    	lda 	#<__DESTRUCTOR_TABLE__
    	ldx 	#>__DESTRUCTOR_TABLE__
    	jmp     condes

.endproc


; --------------------------------------------------------------------------
; Generic table call handler. The code uses self modifying code and goes
; into the data segment for this reason.
; NOTE: The routine must not be called if the table is empty!

.data

.proc	condes

     	sta   	fetch1+1
     	stx	fetch1+2
     	sta   	fetch2+1
     	stx	fetch2+2
loop:   dey
fetch1: lda     $FFFF,y                 ; Patched at runtime
        sta     jmpvec+2
     	dey
fetch2: lda     $FFFF,y                 ; Patched at runtime
        sta     jmpvec+1
       	sty    	index+1
jmpvec: jsr    	$FFFF                   ; Patched at runtime
index: 	ldy    	#$FF                    ; Patched at runtime
       	bne     loop
        rts

.endproc