+++ /dev/null
-#ifndef CCAN_HASH_H
-#define CCAN_HASH_H
-#include <stdint.h>
-#include <stdlib.h>
-#include "config.h"
-
-/* Stolen mostly from: lookup3.c, by Bob Jenkins, May 2006, Public Domain.
- *
- * http://burtleburtle.net/bob/c/lookup3.c
- */
-
-/**
- * hash - fast hash of an array for internal use
- * @p: the array or pointer to first element
- * @num: the number of elements to hash
- * @base: the base number to roll into the hash (usually 0)
- *
- * The memory region pointed to by p is combined with the base to form
- * a 32-bit hash.
- *
- * This hash will have different results on different machines, so is
- * only useful for internal hashes (ie. not hashes sent across the
- * network or saved to disk).
- *
- * It may also change with future versions: it could even detect at runtime
- * what the fastest hash to use is.
- *
- * See also: hash_stable.
- *
- * Example:
- * #include "hash/hash.h"
- * #include <err.h>
- * #include <stdio.h>
- *
- * // Simple demonstration: idential strings will have the same hash, but
- * // two different strings will probably not.
- * int main(int argc, char *argv[])
- * {
- * uint32_t hash1, hash2;
- *
- * if (argc != 3)
- * err(1, "Usage: %s <string1> <string2>", argv[0]);
- *
- * hash1 = hash(argv[1], strlen(argv[1]), 0);
- * hash2 = hash(argv[2], strlen(argv[2]), 0);
- * printf("Hash is %s\n", hash1 == hash2 ? "same" : "different");
- * return 0;
- * }
- */
-#define hash(p, num, base) hash_any((p), (num)*sizeof(*(p)), (base))
-
-/**
- * hash_stable - hash of an array for external use
- * @p: the array or pointer to first element
- * @num: the number of elements to hash
- * @base: the base number to roll into the hash (usually 0)
- *
- * The memory region pointed to by p is combined with the base to form
- * a 32-bit hash.
- *
- * This hash will have the same results on different machines, so can
- * be used for external hashes (ie. not hashes sent across the network
- * or saved to disk). The results will not change in future versions
- * of this package.
- *
- * Example:
- * #include "hash/hash.h"
- * #include <err.h>
- * #include <stdio.h>
- *
- * int main(int argc, char *argv[])
- * {
- * if (argc != 2)
- * err(1, "Usage: %s <string-to-hash>", argv[0]);
- *
- * printf("Hash stable result is %u\n",
- * hash_stable(argv[1], strlen(argv[1]), 0));
- * return 0;
- * }
- */
-#define hash_stable(p, num, base) \
- hash_any_stable((p), (num)*sizeof(*(p)), (base))
-
-/**
- * hash_u32 - fast hash an array of 32-bit values for internal use
- * @key: the array of uint32_t
- * @num: the number of elements to hash
- * @base: the base number to roll into the hash (usually 0)
- *
- * The array of uint32_t pointed to by @key is combined with the base
- * to form a 32-bit hash. This is 2-3 times faster than hash() on small
- * arrays, but the advantage vanishes over large hashes.
- *
- * This hash will have different results on different machines, so is
- * only useful for internal hashes (ie. not hashes sent across the
- * network or saved to disk).
- */
-uint32_t hash_u32(const uint32_t *key, size_t num, uint32_t base);
-
-/* Our underlying operations. */
-uint32_t hash_any(const void *key, size_t length, uint32_t base);
-uint32_t hash_any_stable(const void *key, size_t length, uint32_t base);
-
-/**
- * hash_pointer - hash a pointer for internal use
- * @p: the pointer value to hash
- * @base: the base number to roll into the hash (usually 0)
- *
- * The pointer p (not what p points to!) is combined with the base to form
- * a 32-bit hash.
- *
- * This hash will have different results on different machines, so is
- * only useful for internal hashes (ie. not hashes sent across the
- * network or saved to disk).
- *
- * Example:
- * #include "hash/hash.h"
- *
- * // Code to keep track of memory regions.
- * struct region {
- * struct region *chain;
- * void *start;
- * unsigned int size;
- * };
- * // We keep a simple hash table.
- * static struct region *region_hash[128];
- *
- * static void add_region(struct region *r)
- * {
- * unsigned int h = hash_pointer(r->start);
- *
- * r->chain = region_hash[h];
- * region_hash[h] = r->chain;
- * }
- *
- * static void find_region(const void *start)
- * {
- * struct region *r;
- *
- * for (r = region_hash[hash_pointer(start)]; r; r = r->chain)
- * if (r->start == start)
- * return r;
- * return NULL;
- * }
- */
-static inline uint32_t hash_pointer(const void *p, uint32_t base)
-{
- if (sizeof(p) % sizeof(uint32_t) == 0) {
- /* This convoluted union is the right way of aliasing. */
- union {
- uint32_t u32[sizeof(p) / sizeof(uint32_t)];
- const void *p;
- } u;
- u.p = p;
- return hash_u32(u.u32, sizeof(p) / sizeof(uint32_t), base);
- }
- return hash(&p, 1, base);
-}
-#endif /* HASH_H */
projects / ccan / blobdiff