Squeeze one cycle and several bytes out of the pushax routine.

git-svn-id: svn://svn.cc65.org/cc65/trunk@666 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/runtime/pushax.s

@@ -15,33 +15,21 @@ pusha0:	ldx	#0
 ; Beware^2: The optimizer knows about the value of Y after the function
 ;           returns!
 
-pushax:	ldy	sp
-       	beq	@L1
-       	dey
-       	beq	@L2
-       	dey
-@L0:	sty	sp
-.ifpc02
-      	sta	(sp)		; 65C02 version - saves 2 cycles and one byte
-      	ldy	#1		; get hi index
-.else
-      	ldy	#0    		; get index
-      	sta	(sp),y		; store lo byte
-      	iny	      		; bump idx
-.endif
-      	pha	      		; save it
-      	txa	      		; get hi byte
-    	sta	(sp),y		; store hi byte
-    	pla	    		; get A back
-    	rts	    		; done
-
-@L1:	dey
-@L2:	dey
-    	dec	sp+1
-.ifpc02
-     	bra	@L0
-.else
-    	jmp	@L0
-.endif
+.proc	pushax
 
+	pha
+	lda	sp
+	sec
+	sbc	#2
+	sta	sp		; (13)
+	bcs	@L1
+	dec	sp+1
+@L1:	ldy	#1
+	txa			; (20)
+	sta	(sp),y
+	pla
+	dey
+	sta	(sp),y		; (38)
+	rts
 
+.endproc