1 /* $Id: ioctl.h,v 1.5 1993/07/19 21:53:50 root Exp root $
2 *
3 * linux/ioctl.h for Linux by H.H. Bergman.
4 */
5
6 #ifndef _ASMI386_IOCTL_H
7 #define _ASMI386_IOCTL_H
8
9 /* ioctl command encoding: 32 bits total, command in lower 16 bits,
10 * size of the parameter structure in the lower 14 bits of the
11 * upper 16 bits.
12 * Encoding the size of the parameter structure in the ioctl request
13 * is useful for catching programs compiled with old versions
14 * and to avoid overwriting user space outside the user buffer area.
15 * The highest 2 bits are reserved for indicating the ``access mode''.
16 * NOTE: This limits the max parameter size to 16kB -1 !
17 */
18
19 /*
20 * The following is for compatibility across the various Linux
21 * platforms. The i386 ioctl numbering scheme doesn't really enforce
22 * a type field. De facto, however, the top 8 bits of the lower 16
23 * bits are indeed used as a type field, so we might just as well make
24 * this explicit here. Please be sure to use the decoding macros
25 * below from now on.
26 */
27 #define _IOC_NRBITS 8
28 #define _IOC_TYPEBITS 8
29 #define _IOC_SIZEBITS 14
30 #define _IOC_DIRBITS 2
31
32 #define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
33 #define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1)
34 #define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1)
35 #define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1)
36
37 #define _IOC_NRSHIFT 0
38 #define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS)
39 #define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS)
40 #define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS)
41
42 /*
43 * Direction bits.
44 */
45 #define _IOC_NONE 0U
46 #define _IOC_WRITE 1U
47 #define _IOC_READ 2U
48
49 #define _IOC(dir,type,nr,size) \
50 (((dir) << _IOC_DIRSHIFT) | \
51 ((type) << _IOC_TYPESHIFT) | \
52 ((nr) << _IOC_NRSHIFT) | \
53 ((size) << _IOC_SIZESHIFT))
54
55 /* used to create numbers */
56 #define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
57 #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
58 #define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
59 #define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
60
61 /* used to decode ioctl numbers.. */
62 #define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
63 #define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
64 #define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
65 #define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
66
67 /* ...and for the drivers/sound files... */
68
69 #define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT)
70 #define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT)
71 #define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
72 #define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
73 #define IOCSIZE_SHIFT (_IOC_SIZESHIFT)
74
75 #endif /* _ASMI386_IOCTL_H */
76
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