Runtime function improvements by Piotr Fusik

git-svn-id: svn://svn.cc65.org/cc65/trunk@2577 b7a2c559-68d2-44c3-8de9-860c34a00d81
2003-10-28 08:47:47 +00:00
parent 4319fd9cc7
commit 6d8cdae722
7 changed files with 86 additions and 90 deletions
--- a/libsrc/runtime/subysp.s
+++ b/libsrc/runtime/subysp.s
@@ -1,26 +1,24 @@
 ;
-; Ullrich von Bassewitz, 25.10.2000
+; Piotr Fusik, 24.10.2003
+; originally by Ullrich von Bassewitz
 ;
 ; CC65 runtime: Decrement the stackpointer by value in y
 ;

-       	.export	  	subysp
-	.importzp	sp, tmp1
+	.export		subysp
+	.importzp	sp

 .proc	subysp

-       	sty    	tmp1		; Save the value
-	lda	sp    		; Get lo byte
+	tya
+	eor	#$ff
 	sec
-	sbc	tmp1   	       	; Subtract y value
-	sta	sp  	  	; Put result back
+	adc	sp
+	sta	sp
 	bcs	@L1
 	dec	sp+1
-@L1:   	rts			; Done
+@L1:	rts

 .endproc


-
-
-