+/* Values for bd_state */
+#define BPF_IDLE 0 /* no select in progress or kqueue pending */
+#define BPF_WAITING 1 /* waiting for read timeout in select/kqueue */
+#define BPF_TIMED_OUT 2 /* read timeout has expired in select/kqueue */
+#define BPF_DRAINING 3 /* waiting for timeout routine to finish during close */
+
+/* Test whether a BPF is ready for read(). */
+#define bpf_ready(bd) ((bd)->bd_hlen != 0 || \
+ (((bd)->bd_immediate || (bd)->bd_state == BPF_TIMED_OUT) && \
+ (bd)->bd_slen != 0))
+
+