Set X register to 0 so that 16bit promotion works as expected.

diff --git a/libsrc/c128/isfast.s b/libsrc/c128/isfast.s
index 01b59737197f9b6e50ab371c19ff5986a2ac2ee4..d40e2c7e9b62d97997cc5023906484b26fc0892c 100644 (file)
--- a/libsrc/c128/isfast.s
+++ b/libsrc/c128/isfast.s
@@ -14,6 +14,7 @@
 
         lda     VIC_CLK_128
         and     #$01
+        ldx     #$00
         rts
 
 .endproc