taglinefilesource code
_IOR47include/asm-alpha/ioctl.h#define _IOR(type,nr,size)  _IOC(_IOC_READ,(type),(nr),sizeof(size))
_IOR47include/asm-i386/ioctl.h#define _IOR(c,d,t)  (IOC_OUT | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
_IOR103include/linux/soundcard.h#define  _IOR(x,y,t)  ((int)(IOC_OUT|((sizeof(t)&IOCPARM_MASK)<<16)|(x<<8)|y))