#define FIONBIO     _IOW('f', 126, u_long) /* set/clear non-blocking i/o */

##</code><code>##

#define _IOW(x,y,t)     (IOC_IN|(((long)sizeof(t)&IOCPARM_MASK)<<16)|((x)<<8)|(y))
#define IOCPARM_MASK    0x7f
#define IOC_IN          0x80000000      /* copy in parameters */