taglinefilesource code
_IOW48include/asm-alpha/ioctl.h#define _IOW(type,nr,size)  _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
_IOW47include/linux/ioctl.h#define _IOW(c,d,t)  (IOC_IN | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
_IOW101include/linux/soundcard.h#define  _IOW(x,y,t)  ((int)(IOC_IN|((sizeof(t)&IOCPARM_MASK)<<16)|(x<<8)|y))