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/* $Id: ioctl.h,v 1.5 1993/07/19 21:53:50 root Exp root $
*
* linux/ioctl.h for Linux by H.H. Bergman.
*/
#ifndef _LINUX_IOCTL_H
#define _LINUX_IOCTL_H
/* ioctl command encoding: 32 bits total, command in lower 16 bits,
* size of the parameter structure in the lower 14 bits of the
* upper 16 bits.
* Encoding the size of the parameter structure in the ioctl request
* is useful for catching programs compiled with old versions
* and to avoid overwriting user space outside the user buffer area.
* The highest 2 bits are reserved for indicating the ``access mode''.
* NOTE: This limits the max parameter size to 16kB -1 !
*/
#define IOC_VOID 0x00000000 /* param in size field */
#define IOC_IN 0x40000000 /* user --> kernel */
#define IOC_OUT 0x80000000 /* kernel --> user */
#define IOC_INOUT (IOC_IN | IOC_OUT) /* both */
#define IOCSIZE_MASK 0x3fff0000 /* size (max 16k-1 bytes) */
#define IOCSIZE_SHIFT 16 /* how to get the size */
#define IOCSIZE_MAX ((PAGE_SIZE-1)&(IOCSIZE_MASK >> IOC_SHIFT))
#define IOCCMD_MASK 0x0000ffff /* command code */
#define IOCCMD_SHIFT 0
#define IOCPARM_MASK IOCCMD_MASK
#define IOCPARM_SHIFT IOCCMD_SHIFT
#define IOC_SIZE(cmd) (((cmd) & IOCSIZE_MASK) >> IOCSIZE_SHIFT)
#define IOCBASECMD(cmd) ((cmd) & ~IOCPARM_MASK)
#define IOCGROUP(cmd) (((cmd) >> 8) & 0xFF)
/* _IO(magic, subcode); size field is zero and the
* subcode determines the command.
*/
#define _IO(c,d) (IOC_VOID | ((c)<<8) | (d)) /* param encoded */
/* _IOXX(magic, subcode, arg_t); where arg_t is the type of the
* (last) argument field in the ioctl call, if present.
*/
#define _IOW(c,d,t) (IOC_IN | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
((c)<<8) | (d))
#define _IOR(c,d,t) (IOC_OUT | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
((c)<<8) | (d))
/* WR rather than RW to avoid conflict with stdio.h */
#define _IOWR(c,d,t) (IOC_INOUT | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
((c)<<8) | (d))
#endif /* _LINUX_IOCTL_H */
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