removed jmpvec in favor of callax function

git-svn-id: svn://svn.cc65.org/cc65/trunk@1841 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/geos/common/_sys.s

@@ -0,0 +1,79 @@
+;
+; void __fastcall__ _sys (struct regs* r);
+;
+; Ullrich von Bassewitz, 16.12.1998
+;
+;
+; The function could also export jmpvec as general purpose jump vector that
+; lies in the data segment so it's address may be patched at runtime.
+;
+
+  	.export		__sys
+	.importzp	ptr1
+
+
+__sys:	sta	ptr1
+	stx	ptr1+1	      	; Save the pointer to r
+
+; Fetch the PC and store it into the jump vector
+
+	ldy	#5
+	lda	(ptr1),y
+	sta	jmpvec+2
+	dey	
+	lda	(ptr1),y
+	sta	jmpvec+1
+
+; Get the flags, mask unnecessary bits and push them. Push a
+
+	dey
+	lda	(ptr1),y
+	and	#%11001011
+	pha
+	ldy	#0
+	lda	(ptr1),y
+	pha
+
+; Get and assign X and Y
+
+	iny
+	lda	(ptr1),y
+	tay
+	iny
+	lda	(ptr1),y
+	tay
+
+; Set a and the flags, call the machine code routine
+
+	pla
+	plp
+	jsr	jmpvec
+
+; Back from the routine. Save the flags and a
+
+	php
+	pha
+
+; Put the register values into the regs structure
+
+	tya
+	ldy	#2
+	sta	(ptr1),y
+	dey
+	txa
+	sta	(ptr1),y
+	dey
+	pla
+	sta	(ptr1),y
+	ldy	#3
+	pla
+	sta	(ptr1),y
+
+; Done
+
+	rts
+
+.data
+
+jmpvec:	jmp	$FFFF
+