firFilter

scope(failure) {writefln("Unittest failure :%s(%s)", __FILE__, __LINE__); stdout.flush();}
scope(success) {writefln("Unittest success :%s(%s)", __FILE__, __LINE__); stdout.flush();}

auto arr = [0, 1, 2, 3].repeatStream,
     flt1 = arr.firFilter([0, 1]);

assert(flt1.read(new int[8]) == [0, 0, 0*1+1*0, 1, 2, 3, 0, 1]);

auto flt2 = arr.firFilter([1, 2]);
assert(flt2.read(new int[6]) == [0, 0, 0*2+1*1, 1*2+2*1, 2*2+3*1, 3*2+0*1]);