taglinefilesource code
_IOR40include/linux/ioctl.h#define _IOR(c,d,t)  (IOC_OUT | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
_IOR76include/linux/soundcard.h#define  _IOR(x,y,t)  ((int)(IOC_OUT|((sizeof(t)&IOCPARM_MASK)<<16)|(x<<8)|y))