diff options
author | Ashlee Young <ashlee@onosfw.com> | 2015-09-09 22:21:41 -0700 |
---|---|---|
committer | Ashlee Young <ashlee@onosfw.com> | 2015-09-09 22:21:41 -0700 |
commit | 8879b125d26e8db1a5633de5a9c692eb2d1c4f83 (patch) | |
tree | c7259d85a991b83dfa85ab2e339360669fc1f58e /framework/src/suricata/src/util-hash-lookup3.h | |
parent | 13d05bc8458758ee39cb829098241e89616717ee (diff) |
suricata checkin based on commit id a4bce14770beee46a537eda3c3f6e8e8565d5d0a
Change-Id: I9a214fa0ee95e58fc640e50bd604dac7f42db48f
Diffstat (limited to 'framework/src/suricata/src/util-hash-lookup3.h')
-rw-r--r-- | framework/src/suricata/src/util-hash-lookup3.h | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/framework/src/suricata/src/util-hash-lookup3.h b/framework/src/suricata/src/util-hash-lookup3.h new file mode 100644 index 00000000..1e37e910 --- /dev/null +++ b/framework/src/suricata/src/util-hash-lookup3.h @@ -0,0 +1,63 @@ +/* +------------------------------------------------------------------------------- +lookup3.c, by Bob Jenkins, May 2006, Public Domain. + +These are functions for producing 32-bit hashes for hash table lookup. +hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final() +are externally useful functions. Routines to test the hash are included +if SELF_TEST is defined. You can use this free for any purpose. It's in +the public domain. It has no warranty. + +You probably want to use hashlittle(). hashlittle() and hashbig() +hash byte arrays. hashlittle() is is faster than hashbig() on +little-endian machines. Intel and AMD are little-endian machines. +On second thought, you probably want hashlittle2(), which is identical to +hashlittle() except it returns two 32-bit hashes for the price of one. +You could implement hashbig2() if you wanted but I haven't bothered here. + +If you want to find a hash of, say, exactly 7 integers, do + a = i1; b = i2; c = i3; + mix(a,b,c); + a += i4; b += i5; c += i6; + mix(a,b,c); + a += i7; + final(a,b,c); +then use c as the hash value. If you have a variable length array of +4-byte integers to hash, use hashword(). If you have a byte array (like +a character string), use hashlittle(). If you have several byte arrays, or +a mix of things, see the comments above hashlittle(). + +Why is this so big? I read 12 bytes at a time into 3 4-byte integers, +then mix those integers. This is fast (you can do a lot more thorough +mixing with 12*3 instructions on 3 integers than you can with 3 instructions +on 1 byte), but shoehorning those bytes into integers efficiently is messy. +------------------------------------------------------------------------------- +*/ + +#ifndef __UTIL_HASH_LOOKUP3_H__ +#define __UTIL_HASH_LOOKUP3_H__ + +#define hashsize(n) ((uint32_t)1<<(n)) +#define hashmask(n) (hashsize(n)-1) + +uint32_t hashword(const uint32_t *k, /* the key, an array of uint32_t values */ + size_t length, /* the length of the key, in uint32_ts */ + uint32_t initval); /* the previous hash, or an arbitrary value */ + + +void hashword2 (const uint32_t *k, /* the key, an array of uint32_t values */ + size_t length, /* the length of the key, in uint32_ts */ + uint32_t *pc, /* IN: seed OUT: primary hash value */ + uint32_t *pb); /* IN: more seed OUT: secondary hash value */ + +uint32_t hashlittle( const void *key, size_t length, uint32_t initval); + +void hashlittle2(const void *key, /* the key to hash */ + size_t length, /* length of the key */ + uint32_t *pc, /* IN: primary initval, OUT: primary hash */ + uint32_t *pb); /* IN: secondary initval, OUT: secondary hash */ + +uint32_t hashbig( const void *key, size_t length, uint32_t initval); + +#endif /* __UTIL_HASH_LOOKUP3_H__ */ + |