New pushwysp implementation

git-svn-id: svn://svn.cc65.org/cc65/trunk@1071 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/runtime/pushwsp.s

@@ -8,13 +8,24 @@
       	.import		pushax
       	.importzp	sp
 
+	.macpack	generic
+
 pushw0sp:
-      	ldy	#1
+      	ldy	#2
 pushwysp:
-      	lda	(sp),y		; get hi byte
-      	tax
-      	dey
-      	lda	(sp),y		; get lo byte
-       	jmp	pushax		; push that
-
+	lda	sp	       	; 3
+       	sub    	#2     	       	; 4
+	sta	sp		; 3
+	bcs	@L1		; 3(+1)
+	dec	sp+1		; (5)
+@L1:	lda	(sp),y		; 5 =16
+	tax			; 2
+	dey			; 2
+	lda	(sp),y		; 5
+	ldy	#$00		; 2
+	sta	(sp),y		; 5
+	iny			; 2
+	txa			; 2
+	sta	(sp),y		; 5
+	rts