X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=libsrc%2Fruntime%2Fsub.s;h=1240737adcbcca44587d7b221e2605f932f7d19b;hb=bc6dadb3dbddcb1923c628102aa6342cd356cec0;hp=9108b271059d1d5f8b8756b24ea04f0b7d76fd2f;hpb=53dd513176425872128ef26031d00952ef7a0628;p=cc65

diff --git a/libsrc/runtime/sub.s b/libsrc/runtime/sub.s
index 9108b2710..1240737ad 100644
--- a/libsrc/runtime/sub.s
+++ b/libsrc/runtime/sub.s
@@ -5,8 +5,8 @@
 ;
 
        	.export		tossuba0, tossubax
-	.import		addysp1		
-	.importzp	sp, ptr1
+	.import		addysp1
+	.importzp	sp
 
 ;
 ; AX = TOS - AX
@@ -15,17 +15,21 @@
 tossuba0:
 	ldx	#0
 tossubax:
-	ldy	#0
-	sta	ptr1
-	stx	ptr1+1
-	lda	(sp),y		; lo byte
-	sec
-	sbc	ptr1
-	sta	ptr1		; save lo byte
+      	sec
+      	eor	#$FF
+.ifpc02
+        adc	(sp)
+	ldy	#1
+.else
+      	ldy	#0
+      	adc	(sp),y		; Subtract low byte
 	iny
-	lda	(sp),y
-	sbc	ptr1+1
-	tax
-	lda	ptr1
-	jmp	addysp1		; drop TOS, set condition codes
+.endif
+	pha			; Save high byte
+        txa
+	eor	#$FF
+	adc	(sp),y		; Subtract high byte
+	tax			; High byte into X
+	pla			; Restore low byte
+	jmp	addysp1		; drop TOS