#!/usr/bin/perl
#
# Given a C #define, surround it with
#   #ifndef foo
#   #define foo
#   #endif

for (<>) {
	if (/^#(\s*)define(\s+)([A-Za-z0-9_]*)/) {
		print "#$1ifndef$2$3\n";
		print;
		print "#endif\n";
	}
}