diff options
Diffstat (limited to 'lib/birdlib.h')
| -rw-r--r-- | lib/birdlib.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/lib/birdlib.h b/lib/birdlib.h index e03bd0b2..b7226411 100644 --- a/lib/birdlib.h +++ b/lib/birdlib.h @@ -162,6 +162,7 @@ void bug(const char *msg, ...) NORET; void debug(const char *msg, ...); /* Printf to debug output */ void debug_safe(const char *msg); /* Printf to debug output, async-safe */ + /* Debugging */ #if defined(LOCAL_DEBUG) || defined(GLOBAL_DEBUG) @@ -196,10 +197,36 @@ asm( ); #endif + /* Pseudorandom numbers */ u32 random_u32(void); void random_init(void); void random_bytes(void *buf, size_t size); + +/* Hashing */ + +/* Constant parameter for non-parametrized hashes */ +#define HASH_PARAM 2902958171u + +/* Precomputed powers of HASH_PARAM */ +#define HASH_PARAM1 ((u64) HASH_PARAM) +#define HASH_PARAM2 (HASH_PARAM1 * HASH_PARAM) +#define HASH_PARAM3 (HASH_PARAM2 * HASH_PARAM) +#define HASH_PARAM4 (HASH_PARAM3 * HASH_PARAM) + +/* Reduce intermediate 64-bit value to final 32-bit value */ +static inline u32 hash_value(u64 a) +{ return ((u32) a) ^ ((u32) (a >> 32)); } + +static inline u64 u32_hash0(u32 v, u32 p, u64 acc) +{ return (acc + v) * p; } + +static inline u64 u64_hash0(u64 v, u32 p, u64 acc) +{ return u32_hash0(v >> 32, p, u32_hash0(v, p, acc)); } + +static inline u32 u64_hash(u64 v) +{ return hash_value(u64_hash0(v, HASH_PARAM, 0)); } + #endif |