tnum.h (3467B)
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 9#ifndef _LINUX_TNUM_H 10#define _LINUX_TNUM_H 11 12#include <linux/types.h> 13 14struct tnum { 15 u64 value; 16 u64 mask; 17}; 18 19/* Constructors */ 20/* Represent a known constant as a tnum. */ 21struct tnum tnum_const(u64 value); 22/* A completely unknown value */ 23extern const struct tnum tnum_unknown; 24/* A value that's unknown except that @min <= value <= @max */ 25struct tnum tnum_range(u64 min, u64 max); 26 27/* Arithmetic and logical ops */ 28/* Shift a tnum left (by a fixed shift) */ 29struct tnum tnum_lshift(struct tnum a, u8 shift); 30/* Shift (rsh) a tnum right (by a fixed shift) */ 31struct tnum tnum_rshift(struct tnum a, u8 shift); 32/* Shift (arsh) a tnum right (by a fixed min_shift) */ 33struct tnum tnum_arshift(struct tnum a, u8 min_shift, u8 insn_bitness); 34/* Add two tnums, return @a + @b */ 35struct tnum tnum_add(struct tnum a, struct tnum b); 36/* Subtract two tnums, return @a - @b */ 37struct tnum tnum_sub(struct tnum a, struct tnum b); 38/* Bitwise-AND, return @a & @b */ 39struct tnum tnum_and(struct tnum a, struct tnum b); 40/* Bitwise-OR, return @a | @b */ 41struct tnum tnum_or(struct tnum a, struct tnum b); 42/* Bitwise-XOR, return @a ^ @b */ 43struct tnum tnum_xor(struct tnum a, struct tnum b); 44/* Multiply two tnums, return @a * @b */ 45struct tnum tnum_mul(struct tnum a, struct tnum b); 46 47/* Return a tnum representing numbers satisfying both @a and @b */ 48struct tnum tnum_intersect(struct tnum a, struct tnum b); 49 50/* Return @a with all but the lowest @size bytes cleared */ 51struct tnum tnum_cast(struct tnum a, u8 size); 52 53/* Returns true if @a is a known constant */ 54static inline bool tnum_is_const(struct tnum a) 55{ 56 return !a.mask; 57} 58 59/* Returns true if @a == tnum_const(@b) */ 60static inline bool tnum_equals_const(struct tnum a, u64 b) 61{ 62 return tnum_is_const(a) && a.value == b; 63} 64 65/* Returns true if @a is completely unknown */ 66static inline bool tnum_is_unknown(struct tnum a) 67{ 68 return !~a.mask; 69} 70 71/* Returns true if @a is known to be a multiple of @size. 72 * @size must be a power of two. 73 */ 74bool tnum_is_aligned(struct tnum a, u64 size); 75 76/* Returns true if @b represents a subset of @a. */ 77bool tnum_in(struct tnum a, struct tnum b); 78 79/* Formatting functions. These have snprintf-like semantics: they will write 80 * up to @size bytes (including the terminating NUL byte), and return the number 81 * of bytes (excluding the terminating NUL) which would have been written had 82 * sufficient space been available. (Thus tnum_sbin always returns 64.) 83 */ 84/* Format a tnum as a pair of hex numbers (value; mask) */ 85int tnum_strn(char *str, size_t size, struct tnum a); 86/* Format a tnum as tristate binary expansion */ 87int tnum_sbin(char *str, size_t size, struct tnum a); 88 89/* Returns the 32-bit subreg */ 90struct tnum tnum_subreg(struct tnum a); 91/* Returns the tnum with the lower 32-bit subreg cleared */ 92struct tnum tnum_clear_subreg(struct tnum a); 93/* Returns the tnum with the lower 32-bit subreg set to value */ 94struct tnum tnum_const_subreg(struct tnum a, u32 value); 95/* Returns true if 32-bit subreg @a is a known constant*/ 96static inline bool tnum_subreg_is_const(struct tnum a) 97{ 98 return !(tnum_subreg(a)).mask; 99} 100 101#endif /* _LINUX_TNUM_H */