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- /* 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.
- */
- #ifndef _LINUX_TNUM_H
- #define _LINUX_TNUM_H
- #include <linux/types.h>
- 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;
- /* An unknown value that is a superset of @min <= value <= @max.
- *
- * Could include values outside the range of [@min, @max].
- * For example tnum_range(0, 2) is represented by {0, 1, 2, *3*},
- * rather than the intended set of {0, 1, 2}.
- */
- 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 (rsh) a tnum right (by a fixed shift) */
- struct tnum tnum_rshift(struct tnum a, u8 shift);
- /* Shift (arsh) a tnum right (by a fixed min_shift) */
- struct tnum tnum_arshift(struct tnum a, u8 min_shift, u8 insn_bitness);
- /* 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.
- *
- * Note that using tnum_range() as @a requires extra cautions as tnum_in() may
- * return true unexpectedly due to tnum limited ability to represent tight
- * range, e.g.
- *
- * tnum_in(tnum_range(0, 2), tnum_const(3)) == true
- *
- * As a rule of thumb, if @a is explicitly coded rather than coming from
- * reg->var_off, it should be in form of tnum_const(), tnum_range(0, 2**n - 1),
- * or tnum_range(2**n, 2**(n+1) - 1).
- */
- 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);
- /* Returns the 32-bit subreg */
- struct tnum tnum_subreg(struct tnum a);
- /* Returns the tnum with the lower 32-bit subreg cleared */
- struct tnum tnum_clear_subreg(struct tnum a);
- /* Returns the tnum with the lower 32-bit subreg set to value */
- struct tnum tnum_const_subreg(struct tnum a, u32 value);
- /* Returns true if 32-bit subreg @a is a known constant*/
- static inline bool tnum_subreg_is_const(struct tnum a)
- {
- return !(tnum_subreg(a)).mask;
- }
- #endif /* _LINUX_TNUM_H */
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