8 sed -e 's/^#/##/' <$2/$f >a
9 sed -e 's/^#/##/' <$3/$f >b
10 diff --ifdef=$1 a b |./ifdef.py |sed -e 's/^#if\([^@]*\)@@/@#if\1@/; s/@@#else\([^@]*\)/@#else\1@/; s/@@#endif\([^@]*\)/@#endif\1@/' >$4/$f
12 sed -e 's/^#/##/' <$2/$f >$4/$f
20 sed -e 's/^#/##/' <$3/$f >$4/$f