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f1174f77 EC |
1 | /* tnum: tracked (or tristate) numbers |
2 | * | |
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. | |
7 | */ | |
8 | #include <linux/types.h> | |
9 | ||
10 | struct tnum { | |
11 | u64 value; | |
12 | u64 mask; | |
13 | }; | |
14 | ||
15 | /* Constructors */ | |
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; | |
b03c9f9f EC |
20 | /* A value that's unknown except that @min <= value <= @max */ |
21 | struct tnum tnum_range(u64 min, u64 max); | |
f1174f77 EC |
22 | |
23 | /* Arithmetic and logical ops */ | |
24 | /* Shift a tnum left (by a fixed shift) */ | |
25 | struct tnum tnum_lshift(struct tnum a, u8 shift); | |
9cbe1f5a | 26 | /* Shift (rsh) a tnum right (by a fixed shift) */ |
f1174f77 | 27 | struct tnum tnum_rshift(struct tnum a, u8 shift); |
9cbe1f5a YS |
28 | /* Shift (arsh) a tnum right (by a fixed min_shift) */ |
29 | struct tnum tnum_arshift(struct tnum a, u8 min_shift); | |
f1174f77 EC |
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); | |
42 | ||
43 | /* Return a tnum representing numbers satisfying both @a and @b */ | |
44 | struct tnum tnum_intersect(struct tnum a, struct tnum b); | |
45 | ||
46 | /* Return @a with all but the lowest @size bytes cleared */ | |
47 | struct tnum tnum_cast(struct tnum a, u8 size); | |
48 | ||
49 | /* Returns true if @a is a known constant */ | |
50 | static inline bool tnum_is_const(struct tnum a) | |
51 | { | |
52 | return !a.mask; | |
53 | } | |
54 | ||
55 | /* Returns true if @a == tnum_const(@b) */ | |
56 | static inline bool tnum_equals_const(struct tnum a, u64 b) | |
57 | { | |
58 | return tnum_is_const(a) && a.value == b; | |
59 | } | |
60 | ||
61 | /* Returns true if @a is completely unknown */ | |
62 | static inline bool tnum_is_unknown(struct tnum a) | |
63 | { | |
64 | return !~a.mask; | |
65 | } | |
66 | ||
67 | /* Returns true if @a is known to be a multiple of @size. | |
68 | * @size must be a power of two. | |
69 | */ | |
70 | bool tnum_is_aligned(struct tnum a, u64 size); | |
71 | ||
72 | /* Returns true if @b represents a subset of @a. */ | |
73 | bool tnum_in(struct tnum a, struct tnum b); | |
74 | ||
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.) | |
79 | */ | |
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); |