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

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

.segment        "ONCE"

.proc   initlib

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

.endproc


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

.code

.proc   donelib

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

.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