taglinefilesource code
_IOWR43include/linux/ioctl.h#define _IOWR(c,d,t)  (IOC_INOUT | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
_IOWR81include/linux/soundcard.h#define  _IOWR(x,y,t)  ((int)(IOC_INOUT|((sizeof(t)&IOCPARM_MASK)<<16)|(x<<8)|y))