More additions

git-svn-id: svn://svn.cc65.org/cc65/trunk@2128 b7a2c559-68d2-44c3-8de9-860c34a00d81
2003-05-02 15:00:45 +00:00
parent 51a9e4351b
commit 58b9530c2b
15 changed files with 522 additions and 0 deletions
--- a/libsrc/nes/revers.s
+++ b/libsrc/nes/revers.s
@@ -0,0 +1,27 @@
+;
+; Ullrich von Bassewitz, 07.08.1998
+;
+; unsigned char revers (unsigned char onoff);
+;
+
+      	.export		_revers
+
+        .include        "nes.inc"
+
+.proc   _revers
+
+	ldx    	#$00		; Assume revers off
+	tay			; Test onoff
+	beq	L1		; Jump if off
+	ldx	#$80		; Load on value
+        ldy	#$00		; Assume old value is zero
+L1:     lda    	RVS             ; Load old value
+	stx	RVS             ; Set new value
+	beq	L2		; Jump if old value zero
+	iny			; Make old value = 1
+L2:	ldx	#$00		; Load high byte of result
+	tya			; Load low byte, set CC
+	rts
+
+.endproc
+