implemented 2 more simple math routines

c64/basic/,stubs_math/bbd4.MOVMF2.s

@@ -0,0 +1,24 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - copy FAC1 to memory location, rounds if asked
+//
+// Input:
+// - .X - address low byte
+// - .Y - address high byte
+// - $70 - if MSB is set performs rouding
+//
+// Output:
+// - .A - FAC1 exponent
+//
+// See also:
+// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
+// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
+//
+
+// XXX provide implementation
+
+MOVFM2:
+	STUB_IMPLEMENTATION()