extern int ndmchan_post_poll (struct ndmchan *chtab[], unsigned n_chtab);
extern void ndmchan_compress (struct ndmchan *ch);
extern int ndmchan_n_avail (struct ndmchan *ch);
extern int ndmchan_post_poll (struct ndmchan *chtab[], unsigned n_chtab);
extern void ndmchan_compress (struct ndmchan *ch);
extern int ndmchan_n_avail (struct ndmchan *ch);