added more floating point stubs

c64/basic/,stubs_math/b947.inv_FAC1_mantissa.s

@@ -0,0 +1,19 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - invert FAC1 mantissa
+//
+// See also:
+// - [CM64] Computes Mapping the Commodore 64 - page 113
+// - https://www.c64-wiki.com/wiki/BASIC-ROM
+// - https://sta.c64.org/cbm64basconv.html
+//
+
+// XXX implement, test
+
+
+inv_FAC1_mantissa:
+
+	STUB_IMPLEMENTATION()