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 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 ``` ``````/* tnum: tracked (or tristate) numbers * * A tnum tracks knowledge about the bits of a value. Each bit can be either * known (0 or 1), or unknown (x). Arithmetic operations on tnums will * propagate the unknown bits such that the tnum result represents all the * possible results for possible values of the operands. */ #include struct tnum { u64 value; u64 mask; }; /* Constructors */ /* Represent a known constant as a tnum. */ struct tnum tnum_const(u64 value); /* A completely unknown value */ extern const struct tnum tnum_unknown; /* A value that's unknown except that @min <= value <= @max */ struct tnum tnum_range(u64 min, u64 max); /* Arithmetic and logical ops */ /* Shift a tnum left (by a fixed shift) */ struct tnum tnum_lshift(struct tnum a, u8 shift); /* Shift a tnum right (by a fixed shift) */ struct tnum tnum_rshift(struct tnum a, u8 shift); /* Add two tnums, return @a + @b */ struct tnum tnum_add(struct tnum a, struct tnum b); /* Subtract two tnums, return @a - @b */ struct tnum tnum_sub(struct tnum a, struct tnum b); /* Bitwise-AND, return @a & @b */ struct tnum tnum_and(struct tnum a, struct tnum b); /* Bitwise-OR, return @a | @b */ struct tnum tnum_or(struct tnum a, struct tnum b); /* Bitwise-XOR, return @a ^ @b */ struct tnum tnum_xor(struct tnum a, struct tnum b); /* Multiply two tnums, return @a * @b */ struct tnum tnum_mul(struct tnum a, struct tnum b); /* Return a tnum representing numbers satisfying both @a and @b */ struct tnum tnum_intersect(struct tnum a, struct tnum b); /* Return @a with all but the lowest @size bytes cleared */ struct tnum tnum_cast(struct tnum a, u8 size); /* Returns true if @a is a known constant */ static inline bool tnum_is_const(struct tnum a) { return !a.mask; } /* Returns true if @a == tnum_const(@b) */ static inline bool tnum_equals_const(struct tnum a, u64 b) { return tnum_is_const(a) && a.value == b; } /* Returns true if @a is completely unknown */ static inline bool tnum_is_unknown(struct tnum a) { return !~a.mask; } /* Returns true if @a is known to be a multiple of @size. * @size must be a power of two. */ bool tnum_is_aligned(struct tnum a, u64 size); /* Returns true if @b represents a subset of @a. */ bool tnum_in(struct tnum a, struct tnum b); /* Formatting functions. These have snprintf-like semantics: they will write * up to @size bytes (including the terminating NUL byte), and return the number * of bytes (excluding the terminating NUL) which would have been written had * sufficient space been available. (Thus tnum_sbin always returns 64.) */ /* Format a tnum as a pair of hex numbers (value; mask) */ int tnum_strn(char *str, size_t size, struct tnum a); /* Format a tnum as tristate binary expansion */ int tnum_sbin(char *str, size_t size, struct tnum a); ``````