path: root/Documentation/technical/api-hashmap.txt
diff options
authorKarsten Blees <>2014-07-02 22:20:20 (GMT)
committerJunio C Hamano <>2014-07-07 20:56:24 (GMT)
commit039dc71a7cb824300e242f8abc0fcb19dac93641 (patch)
tree9c38bb8655e0314cfe122b7355922c2413533825 /Documentation/technical/api-hashmap.txt
parent6f92e5ff3cdc813de8ef5327fd4bad492fb7d6c9 (diff)
hashmap: factor out getting a hash code from a SHA1
Copying the first bytes of a SHA1 is duplicated in six places, however, the implications (the actual value would depend on the endianness of the platform) is documented only once. Add a properly documented API for this. Signed-off-by: Karsten Blees <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'Documentation/technical/api-hashmap.txt')
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/technical/api-hashmap.txt b/Documentation/technical/api-hashmap.txt
index b977ae8..37727cd 100644
--- a/Documentation/technical/api-hashmap.txt
+++ b/Documentation/technical/api-hashmap.txt
@@ -58,6 +58,15 @@ Functions
`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.