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1 /* tnum: tracked (or tristate) numbers
3 * A tnum tracks knowledge about the bits of a value. Each bit can be either
4 * known (0 or 1), or unknown (x). Arithmetic operations on tnums will
5 * propagate the unknown bits such that the tnum result represents all the
6 * possible results for possible values of the operands.
8 #include <linux/types.h>
16 /* Represent a known constant as a tnum. */
17 struct tnum
tnum_const(u64 value
);
18 /* A completely unknown value */
19 extern const struct tnum tnum_unknown
;
20 /* A value that's unknown except that @min <= value <= @max */
21 struct tnum
tnum_range(u64 min
, u64 max
);
23 /* Arithmetic and logical ops */
24 /* Shift a tnum left (by a fixed shift) */
25 struct tnum
tnum_lshift(struct tnum a
, u8 shift
);
26 /* Shift (rsh) a tnum right (by a fixed shift) */
27 struct tnum
tnum_rshift(struct tnum a
, u8 shift
);
28 /* Shift (arsh) a tnum right (by a fixed min_shift) */
29 struct tnum
tnum_arshift(struct tnum a
, u8 min_shift
);
30 /* Add two tnums, return @a + @b */
31 struct tnum
tnum_add(struct tnum a
, struct tnum b
);
32 /* Subtract two tnums, return @a - @b */
33 struct tnum
tnum_sub(struct tnum a
, struct tnum b
);
34 /* Bitwise-AND, return @a & @b */
35 struct tnum
tnum_and(struct tnum a
, struct tnum b
);
36 /* Bitwise-OR, return @a | @b */
37 struct tnum
tnum_or(struct tnum a
, struct tnum b
);
38 /* Bitwise-XOR, return @a ^ @b */
39 struct tnum
tnum_xor(struct tnum a
, struct tnum b
);
40 /* Multiply two tnums, return @a * @b */
41 struct tnum
tnum_mul(struct tnum a
, struct tnum b
);
43 /* Return a tnum representing numbers satisfying both @a and @b */
44 struct tnum
tnum_intersect(struct tnum a
, struct tnum b
);
46 /* Return @a with all but the lowest @size bytes cleared */
47 struct tnum
tnum_cast(struct tnum a
, u8 size
);
49 /* Returns true if @a is a known constant */
50 static inline bool tnum_is_const(struct tnum a
)
55 /* Returns true if @a == tnum_const(@b) */
56 static inline bool tnum_equals_const(struct tnum a
, u64 b
)
58 return tnum_is_const(a
) && a
.value
== b
;
61 /* Returns true if @a is completely unknown */
62 static inline bool tnum_is_unknown(struct tnum a
)
67 /* Returns true if @a is known to be a multiple of @size.
68 * @size must be a power of two.
70 bool tnum_is_aligned(struct tnum a
, u64 size
);
72 /* Returns true if @b represents a subset of @a. */
73 bool tnum_in(struct tnum a
, struct tnum b
);
75 /* Formatting functions. These have snprintf-like semantics: they will write
76 * up to @size bytes (including the terminating NUL byte), and return the number
77 * of bytes (excluding the terminating NUL) which would have been written had
78 * sufficient space been available. (Thus tnum_sbin always returns 64.)
80 /* Format a tnum as a pair of hex numbers (value; mask) */
81 int tnum_strn(char *str
, size_t size
, struct tnum a
);
82 /* Format a tnum as tristate binary expansion */
83 int tnum_sbin(char *str
, size_t size
, struct tnum a
);