utils: add mask_merge.sh

Signed-off-by: Alessandro Comodi <acomodi@antmicro.com>

utils/maskmerge.sh

diff --git a/utils/maskmerge.sh b/utils/maskmerge.sh
new file mode 100755
index 0000000..e334b65
--- /dev/null
+++ b/utils/maskmerge.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+
+outfile="$1"
+shift
+
+touch "$outfile"
+mv "$outfile" "$outfile.tmp"
+
+for infile; do
+	echo "Reading mask bits from $infile."
+	grep ^bit "$infile" | sort -u >> "$outfile.tmp"
+done
+
+sort -u < "$outfile.tmp" > "$outfile"
+rm -f "$outfile.tmp"
+