+
`strihash` and `memihash` are case insensitive versions.
+`unsigned int sha1hash(const unsigned char *sha1)`::
+
+ Converts a cryptographic hash (e.g. SHA-1) into an int-sized hash code
+ for use in hash tables. Cryptographic hashes are supposed to have
+ uniform distribution, so in contrast to `memhash()`, this just copies
+ the first `sizeof(int)` bytes without shuffling any bits. Note that
+ the results will be different on big-endian and little-endian
+ platforms, so they should not be stored or transferred over the net.
+
`void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function, size_t initial_size)`::
Initializes a hashmap structure.
return hashcmp(cn1->peeled, peeled ? peeled : cn2->peeled);
}
-static inline unsigned int hash_sha1(const unsigned char *sha1)
-{
- unsigned int hash;
- memcpy(&hash, sha1, sizeof(hash));
- return hash;
-}
-
static inline struct commit_name *find_commit_name(const unsigned char *peeled)
{
struct commit_name key;
- hashmap_entry_init(&key, hash_sha1(peeled));
+ hashmap_entry_init(&key, sha1hash(peeled));
return hashmap_get(&names, &key, peeled);
}
if (!e) {
e = xmalloc(sizeof(struct commit_name));
hashcpy(e->peeled, peeled);
- hashmap_entry_init(e, hash_sha1(peeled));
+ hashmap_entry_init(e, sha1hash(peeled));
hashmap_add(&names, e);
e->path = NULL;
}
static unsigned int hash_obj(const struct object *obj, unsigned int n)
{
- unsigned int hash;
-
- memcpy(&hash, obj->sha1, sizeof(unsigned int));
- return hash % n;
+ return sha1hash(obj->sha1) % n;
}
static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
static unsigned int hash_filespec(struct diff_filespec *filespec)
{
- unsigned int hash;
if (!filespec->sha1_valid) {
if (diff_populate_filespec(filespec, 0))
return 0;
hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
}
- memcpy(&hash, filespec->sha1, sizeof(hash));
- return hash;
+ return sha1hash(filespec->sha1);
}
static int find_identical_files(struct hashmap *srcs,
extern unsigned int memhash(const void *buf, size_t len);
extern unsigned int memihash(const void *buf, size_t len);
+static inline unsigned int sha1hash(const unsigned char *sha1)
+{
+ /*
+ * Equivalent to 'return *(unsigned int *)sha1;', but safe on
+ * platforms that don't support unaligned reads.
+ */
+ unsigned int hash;
+ memcpy(&hash, sha1, sizeof(hash));
+ return hash;
+}
+
/* data structures */
struct hashmap_entry {
code; \
} }
-static inline khint_t __kh_oid_hash(const unsigned char *oid)
-{
- khint_t hash;
- memcpy(&hash, oid, sizeof(hash));
- return hash;
-}
-
#define __kh_oid_cmp(a, b) (hashcmp(a, b) == 0)
-KHASH_INIT(sha1, const unsigned char *, void *, 1, __kh_oid_hash, __kh_oid_cmp)
+KHASH_INIT(sha1, const unsigned char *, void *, 1, sha1hash, __kh_oid_cmp)
typedef kh_sha1_t khash_sha1;
-KHASH_INIT(sha1_pos, const unsigned char *, int, 1, __kh_oid_hash, __kh_oid_cmp)
+KHASH_INIT(sha1_pos, const unsigned char *, int, 1, sha1hash, __kh_oid_cmp)
typedef kh_sha1_pos_t khash_sha1_pos;
#endif /* __AC_KHASH_H */
*/
static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
{
- unsigned int hash;
-
- /*
- * Since the sha1 is essentially random, we just take the
- * required number of bits directly from the first
- * sizeof(unsigned int) bytes of sha1. First we have to copy
- * the bytes into a properly aligned integer. If we cared
- * about getting consistent results across architectures, we
- * would have to call ntohl() here, too.
- */
- memcpy(&hash, sha1, sizeof(unsigned int));
- return hash & (n - 1);
+ return sha1hash(sha1) & (n - 1);
}
/*
const unsigned char *sha1,
int *found)
{
- uint32_t i, hash, mask = (pdata->index_size - 1);
+ uint32_t i, mask = (pdata->index_size - 1);
- memcpy(&hash, sha1, sizeof(uint32_t));
- i = hash & mask;
+ i = sha1hash(sha1) & mask;
while (pdata->index[i] > 0) {
uint32_t pos = pdata->index[i] - 1;