if err := inf.Close(); err != nil {
				t.Fatalf("close failed with: %v", err)
			}
		}()

		if err != nil {
			t.Fatalf("reopening covcounters file: %v", err)
		}
		if cdr, err = decodecounter.NewCounterDataReader(cfpath, inf); err != nil {
			t.Fatalf("opening covcounters for read: %v", err)
		}
		decodedArgs := cdr.OsArgs()
		aWant := "[arg0 arg1 arg_________2]"
		aGot := fmt.Sprintf("%+v", decodedArgs)

		mr, err = NewMreader(cf)
		if err != nil {
			return r.fatal("creating reader for counter data file %s: %s", cdf, err)
		}
		var cdr *decodecounter.CounterDataReader
		cdr, err = decodecounter.NewCounterDataReader(cdf, mr)
		if err != nil {
			return r.fatal("reading counter data file %s: %s", cdf, err)
		}
		r.vis.BeginCounterDataFile(cdf, cdr, p.Origins[k])
		var data decodecounter.FuncPayload
		for {

		cf, err := os.Open(cdf)
		if err != nil {
			return fmt.Errorf("opening counter data file %s: %s", cdf, err)
		}
		defer cf.Close()
		var cdr *decodecounter.CounterDataReader
		cdr, err = decodecounter.NewCounterDataReader(cdf, cf)
		if err != nil {
			return fmt.Errorf("reading counter data file %s: %s", cdf, err)
		}
		var data decodecounter.FuncPayload
		for {
			ok, err := cdr.NextFunc(&data)
			if err != nil {

	ftr      coverage.CounterFileFooter
	shdr     coverage.CounterSegmentHeader
	u32b     []byte
	u8b      []byte
	fcnCount uint32
	segCount uint32
	debug    bool
}

func NewCounterDataReader(fn string, rs io.ReadSeeker) (*CounterDataReader, error) {
	cdr := &CounterDataReader{
		mr:   rs,
		u32b: make([]byte, 4),
		u8b:  make([]byte, 1),
	}
	// Read header