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;
21 /* Arithmetic and logical ops */
22 /* Shift a tnum left (by a fixed shift) */
23 struct tnum tnum_lshift(struct tnum a, u8 shift);
24 /* Shift a tnum right (by a fixed shift) */
25 struct tnum tnum_rshift(struct tnum a, u8 shift);
26 /* Add two tnums, return @a + @b */
27 struct tnum tnum_add(struct tnum a, struct tnum b);
28 /* Subtract two tnums, return @a - @b */
29 struct tnum tnum_sub(struct tnum a, struct tnum b);
30 /* Bitwise-AND, return @a & @b */
31 struct tnum tnum_and(struct tnum a, struct tnum b);
32 /* Bitwise-OR, return @a | @b */
33 struct tnum tnum_or(struct tnum a, struct tnum b);
34 /* Bitwise-XOR, return @a ^ @b */
35 struct tnum tnum_xor(struct tnum a, struct tnum b);
36 /* Multiply two tnums, return @a * @b */
37 struct tnum tnum_mul(struct tnum a, struct tnum b);
39 /* Return a tnum representing numbers satisfying both @a and @b */
40 struct tnum tnum_intersect(struct tnum a, struct tnum b);
42 /* Return @a with all but the lowest @size bytes cleared */
43 struct tnum tnum_cast(struct tnum a, u8 size);
45 /* Returns true if @a is a known constant */
46 static inline bool tnum_is_const(struct tnum a)
51 /* Returns true if @a == tnum_const(@b) */
52 static inline bool tnum_equals_const(struct tnum a, u64 b)
54 return tnum_is_const(a) && a.value == b;
57 /* Returns true if @a is completely unknown */
58 static inline bool tnum_is_unknown(struct tnum a)
63 /* Returns true if @a is known to be a multiple of @size.
64 * @size must be a power of two.
66 bool tnum_is_aligned(struct tnum a, u64 size);
68 /* Returns true if @b represents a subset of @a. */
69 bool tnum_in(struct tnum a, struct tnum b);
71 /* Formatting functions. These have snprintf-like semantics: they will write
72 * up to @size bytes (including the terminating NUL byte), and return the number
73 * of bytes (excluding the terminating NUL) which would have been written had
74 * sufficient space been available. (Thus tnum_sbin always returns 64.)
76 /* Format a tnum as a pair of hex numbers (value; mask) */
77 int tnum_strn(char *str, size_t size, struct tnum a);
78 /* Format a tnum as tristate binary expansion */
79 int tnum_sbin(char *str, size_t size, struct tnum a);