if fd.isBlocking == 0 {
		runtime_Semacquire(&fd.csema)
	}

	return err
}

// SetBlocking puts the file into blocking mode.
func (fd *FD) SetBlocking() error {
	if err := fd.incref(); err != nil {
		return err
	}
	defer fd.decref()
	// Atomic store so that concurrent calls to SetBlocking
	// do not cause a race condition. isBlocking only ever goes
	// from 0 to 1 so there is no real race here.

		t.Fatalf("expect 16 abcd and 4 1234 but got %s. r.w=%d, r.r=%d", rb.Bytes(nil), rb.w, rb.r)
	}
}

func TestRingBuffer_WriteBlocking(t *testing.T) {
	rb := New(64).SetBlocking(true)

	// check empty or full
	if !rb.IsEmpty() {
		t.Fatalf("expect IsEmpty is true but got false")
	}
	if rb.IsFull() {
		t.Fatalf("expect IsFull is false but got true")
	}
	if rb.Length() != 0 {

		size: size,
	}
}

// NewBuffer returns a new RingBuffer whose buffer is provided.
func NewBuffer(b []byte) *RingBuffer {
	return &RingBuffer{
		buf:  b,
		size: len(b),
	}
}

// SetBlocking sets the blocking mode of the ring buffer.
// If block is true, Read and Write will block when there is no data to read or no space to write.
// If block is false, Read and Write will return ErrIsEmpty or ErrIsFull immediately.

	// because historically we have always returned a descriptor
	// opened in blocking mode. The File will continue to work,
	// but any blocking operation will tie up a thread.
	if f.nonblock {
		f.pfd.SetBlocking()
	}

	return uintptr(f.pfd.Sysfd)
}

// NewFile returns a new File with the given file descriptor and
// name. The returned value will be nil if fd is not a valid file