298 lines
9.5 KiB
C
298 lines
9.5 KiB
C
#include "jenkins_hash.h"
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#include <stdlib.h>
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#ifdef WIN32
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#define _USE_MATH_DEFINES //For M_LOG2E
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#endif
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#include <math.h>
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#include <limits.h>
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#include <string.h>
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//#define DEBUG
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#include "debug.h"
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#define hashsize(n) ((cmph_uint32)1<<(n))
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#define hashmask(n) (hashsize(n)-1)
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//#define NM2 /* Define this if you do not want power of 2 table sizes*/
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/*
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--------------------------------------------------------------------
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mix -- mix 3 32-bit values reversibly.
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For every delta with one or two bits set, and the deltas of all three
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high bits or all three low bits, whether the original value of a,b,c
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is almost all zero or is uniformly distributed,
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* If mix() is run forward or backward, at least 32 bits in a,b,c
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have at least 1/4 probability of changing.
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* If mix() is run forward, every bit of c will change between 1/3 and
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2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
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mix() was built out of 36 single-cycle latency instructions in a
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structure that could supported 2x parallelism, like so:
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a -= b;
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a -= c; x = (c>>13);
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b -= c; a ^= x;
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b -= a; x = (a<<8);
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c -= a; b ^= x;
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c -= b; x = (b>>13);
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...
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Unfortunately, superscalar Pentiums and Sparcs can't take advantage
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of that parallelism. They've also turned some of those single-cycle
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latency instructions into multi-cycle latency instructions. Still,
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this is the fastest good hash I could find. There were about 2^^68
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to choose from. I only looked at a billion or so.
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--------------------------------------------------------------------
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*/
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#define mix(a,b,c) \
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{ \
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a -= b; a -= c; a ^= (c>>13); \
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b -= c; b -= a; b ^= (a<<8); \
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c -= a; c -= b; c ^= (b>>13); \
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a -= b; a -= c; a ^= (c>>12); \
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b -= c; b -= a; b ^= (a<<16); \
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c -= a; c -= b; c ^= (b>>5); \
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a -= b; a -= c; a ^= (c>>3); \
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b -= c; b -= a; b ^= (a<<10); \
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c -= a; c -= b; c ^= (b>>15); \
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}
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/*
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--------------------------------------------------------------------
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hash() -- hash a variable-length key into a 32-bit value
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k : the key (the unaligned variable-length array of bytes)
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len : the length of the key, counting by bytes
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initval : can be any 4-byte value
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Returns a 32-bit value. Every bit of the key affects every bit of
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the return value. Every 1-bit and 2-bit delta achieves avalanche.
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About 6*len+35 instructions.
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The best hash table sizes are powers of 2. There is no need to do
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mod a prime (mod is sooo slow!). If you need less than 32 bits,
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use a bitmask. For example, if you need only 10 bits, do
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h = (h & hashmask(10));
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In which case, the hash table should have hashsize(10) elements.
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If you are hashing n strings (cmph_uint8 **)k, do it like this:
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for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h);
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By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. You may use this
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code any way you wish, private, educational, or commercial. It's free.
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See http://burtleburtle.net/bob/hash/evahash.html
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Use for hash table lookup, or anything where one collision in 2^^32 is
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acceptable. Do NOT use for cryptographic purposes.
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--------------------------------------------------------------------
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*/
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jenkins_state_t *jenkins_state_new(cmph_uint32 size) //size of hash table
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{
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jenkins_state_t *state = (jenkins_state_t *)malloc(sizeof(jenkins_state_t));
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DEBUGP("Initializing jenkins hash\n");
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state->seed = ((cmph_uint32)rand() % size);
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return state;
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}
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void jenkins_state_destroy(jenkins_state_t *state)
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{
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free(state);
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}
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inline void __jenkins_hash_vector(cmph_uint32 seed, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes)
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{
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register cmph_uint32 len, length;
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/* Set up the internal state */
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length = keylen;
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len = length;
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hashes[0] = hashes[1] = 0x9e3779b9; /* the golden ratio; an arbitrary value */
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hashes[2] = seed; /* the previous hash value - seed in our case */
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/*---------------------------------------- handle most of the key */
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while (len >= 12)
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{
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hashes[0] += ((cmph_uint32)k[0] +((cmph_uint32)k[1]<<8) +((cmph_uint32)k[2]<<16) +((cmph_uint32)k[3]<<24));
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hashes[1] += ((cmph_uint32)k[4] +((cmph_uint32)k[5]<<8) +((cmph_uint32)k[6]<<16) +((cmph_uint32)k[7]<<24));
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hashes[2] += ((cmph_uint32)k[8] +((cmph_uint32)k[9]<<8) +((cmph_uint32)k[10]<<16)+((cmph_uint32)k[11]<<24));
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mix(hashes[0],hashes[1],hashes[2]);
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k += 12; len -= 12;
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}
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/*------------------------------------- handle the last 11 bytes */
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hashes[2] += length;
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switch(len) /* all the case statements fall through */
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{
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case 11:
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hashes[2] +=((cmph_uint32)k[10]<<24);
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case 10:
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hashes[2] +=((cmph_uint32)k[9]<<16);
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case 9 :
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hashes[2] +=((cmph_uint32)k[8]<<8);
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/* the first byte of hashes[2] is reserved for the length */
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case 8 :
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hashes[1] +=((cmph_uint32)k[7]<<24);
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case 7 :
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hashes[1] +=((cmph_uint32)k[6]<<16);
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case 6 :
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hashes[1] +=((cmph_uint32)k[5]<<8);
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case 5 :
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hashes[1] +=(cmph_uint8) k[4];
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case 4 :
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hashes[0] +=((cmph_uint32)k[3]<<24);
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case 3 :
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hashes[0] +=((cmph_uint32)k[2]<<16);
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case 2 :
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hashes[0] +=((cmph_uint32)k[1]<<8);
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case 1 :
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hashes[0] +=(cmph_uint8)k[0];
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/* case 0: nothing left to add */
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}
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mix(hashes[0],hashes[1],hashes[2]);
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}
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cmph_uint32 jenkins_hash(jenkins_state_t *state, const char *k, cmph_uint32 keylen)
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{
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cmph_uint32 hashes[3];
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__jenkins_hash_vector(state->seed, k, keylen, hashes);
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return hashes[2];
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/* cmph_uint32 a, b, c;
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cmph_uint32 len, length;
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// Set up the internal state
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length = keylen;
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len = length;
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a = b = 0x9e3779b9; // the golden ratio; an arbitrary value
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c = state->seed; // the previous hash value - seed in our case
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// handle most of the key
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while (len >= 12)
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{
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a += (k[0] +((cmph_uint32)k[1]<<8) +((cmph_uint32)k[2]<<16) +((cmph_uint32)k[3]<<24));
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b += (k[4] +((cmph_uint32)k[5]<<8) +((cmph_uint32)k[6]<<16) +((cmph_uint32)k[7]<<24));
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c += (k[8] +((cmph_uint32)k[9]<<8) +((cmph_uint32)k[10]<<16)+((cmph_uint32)k[11]<<24));
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mix(a,b,c);
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k += 12; len -= 12;
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}
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// handle the last 11 bytes
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c += length;
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switch(len) /// all the case statements fall through
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{
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case 11:
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c +=((cmph_uint32)k[10]<<24);
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case 10:
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c +=((cmph_uint32)k[9]<<16);
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case 9 :
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c +=((cmph_uint32)k[8]<<8);
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// the first byte of c is reserved for the length
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case 8 :
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b +=((cmph_uint32)k[7]<<24);
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case 7 :
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b +=((cmph_uint32)k[6]<<16);
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case 6 :
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b +=((cmph_uint32)k[5]<<8);
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case 5 :
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b +=k[4];
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case 4 :
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a +=((cmph_uint32)k[3]<<24);
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case 3 :
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a +=((cmph_uint32)k[2]<<16);
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case 2 :
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a +=((cmph_uint32)k[1]<<8);
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case 1 :
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a +=k[0];
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// case 0: nothing left to add
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}
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mix(a,b,c);
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/// report the result
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return c;
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*/
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}
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void jenkins_hash_vector_(jenkins_state_t *state, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes)
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{
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__jenkins_hash_vector(state->seed, k, keylen, hashes);
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}
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void jenkins_state_dump(jenkins_state_t *state, char **buf, cmph_uint32 *buflen)
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{
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*buflen = sizeof(cmph_uint32);
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*buf = (char *)malloc(sizeof(cmph_uint32));
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if (!*buf)
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{
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*buflen = UINT_MAX;
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return;
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}
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memcpy(*buf, &(state->seed), sizeof(cmph_uint32));
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DEBUGP("Dumped jenkins state with seed %u\n", state->seed);
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return;
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}
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jenkins_state_t *jenkins_state_copy(jenkins_state_t *src_state)
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{
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jenkins_state_t *dest_state = (jenkins_state_t *)malloc(sizeof(jenkins_state_t));
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dest_state->hashfunc = src_state->hashfunc;
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dest_state->seed = src_state->seed;
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return dest_state;
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}
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jenkins_state_t *jenkins_state_load(const char *buf, cmph_uint32 buflen)
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{
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jenkins_state_t *state = (jenkins_state_t *)malloc(sizeof(jenkins_state_t));
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state->seed = *(cmph_uint32 *)buf;
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state->hashfunc = CMPH_HASH_JENKINS;
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DEBUGP("Loaded jenkins state with seed %u\n", state->seed);
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return state;
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}
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/** \fn void jenkins_state_pack(jenkins_state_t *state, void *jenkins_packed);
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* \brief Support the ability to pack a jenkins function into a preallocated contiguous memory space pointed by jenkins_packed.
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* \param state points to the jenkins function
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* \param jenkins_packed pointer to the contiguous memory area used to store the jenkins function. The size of jenkins_packed must be at least jenkins_state_packed_size()
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*/
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void jenkins_state_pack(jenkins_state_t *state, void *jenkins_packed)
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{
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if (state && jenkins_packed)
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{
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memcpy(jenkins_packed, &(state->seed), sizeof(cmph_uint32));
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}
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}
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/** \fn cmph_uint32 jenkins_state_packed_size(jenkins_state_t *state);
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* \brief Return the amount of space needed to pack a jenkins function.
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* \return the size of the packed function or zero for failures
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*/
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cmph_uint32 jenkins_state_packed_size()
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{
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return sizeof(cmph_uint32);
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}
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/** \fn cmph_uint32 jenkins_hash_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen);
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* \param jenkins_packed is a pointer to a contiguous memory area
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* \param key is a pointer to a key
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* \param keylen is the key length
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* \return an integer that represents a hash value of 32 bits.
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*/
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cmph_uint32 jenkins_hash_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen)
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{
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cmph_uint32 hashes[3];
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__jenkins_hash_vector(*((cmph_uint32 *)jenkins_packed), k, keylen, hashes);
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return hashes[2];
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}
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/** \fn jenkins_hash_vector_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes);
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* \param jenkins_packed is a pointer to a contiguous memory area
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* \param key is a pointer to a key
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* \param keylen is the key length
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* \param hashes is a pointer to a memory large enough to fit three 32-bit integers.
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*/
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void jenkins_hash_vector_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes)
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{
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__jenkins_hash_vector(*((cmph_uint32 *)jenkins_packed), k, keylen, hashes);
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}
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