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lookup8.cpp
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//
// Created by icybee&freezer on 2021/4/7.
//
/*
--------------------------------------------------------------------
lookup8.c, by Bob Jenkins, January 4 1997, Public Domain.
hash(), hash2(), hash3, and mix() 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 has no warranty.
2009: This is obsolete. I recently timed lookup3.c as being faster
at producing 64-bit results.
--------------------------------------------------------------------
*/
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include "include/tools/lookup8.h"
ub8 hash1(ub1* k,ub8 length,ub8 level)
{
ub8 a,b,c,len;
/* Set up the internal state */
len = length;
a = b = level; /* the previous hash value */
c = 0x9e3779b97f4a7c13LL; /* the golden ratio; an arbitrary value */
/*---------------------------------------- handle most of the key */
while (len >= 24)
{
a += (k[0] +((ub8)k[ 1]<< 8)+((ub8)k[ 2]<<16)+((ub8)k[ 3]<<24)
+((ub8)k[4 ]<<32)+((ub8)k[ 5]<<40)+((ub8)k[ 6]<<48)+((ub8)k[ 7]<<56));
b += (k[8] +((ub8)k[ 9]<< 8)+((ub8)k[10]<<16)+((ub8)k[11]<<24)
+((ub8)k[12]<<32)+((ub8)k[13]<<40)+((ub8)k[14]<<48)+((ub8)k[15]<<56));
c += (k[16] +((ub8)k[17]<< 8)+((ub8)k[18]<<16)+((ub8)k[19]<<24)
+((ub8)k[20]<<32)+((ub8)k[21]<<40)+((ub8)k[22]<<48)+((ub8)k[23]<<56));
mix64(a,b,c);
k += 24; len -= 24;
}
/*------------------------------------- handle the last 23 bytes */
c += length;
switch(len) /* all the case statements fall through */
{
case 23: c+=((ub8)k[22]<<56);
case 22: c+=((ub8)k[21]<<48);
case 21: c+=((ub8)k[20]<<40);
case 20: c+=((ub8)k[19]<<32);
case 19: c+=((ub8)k[18]<<24);
case 18: c+=((ub8)k[17]<<16);
case 17: c+=((ub8)k[16]<<8);
/* the first byte of c is reserved for the length */
case 16: b+=((ub8)k[15]<<56);
case 15: b+=((ub8)k[14]<<48);
case 14: b+=((ub8)k[13]<<40);
case 13: b+=((ub8)k[12]<<32);
case 12: b+=((ub8)k[11]<<24);
case 11: b+=((ub8)k[10]<<16);
case 10: b+=((ub8)k[ 9]<<8);
case 9: b+=((ub8)k[ 8]);
case 8: a+=((ub8)k[ 7]<<56);
case 7: a+=((ub8)k[ 6]<<48);
case 6: a+=((ub8)k[ 5]<<40);
case 5: a+=((ub8)k[ 4]<<32);
case 4: a+=((ub8)k[ 3]<<24);
case 3: a+=((ub8)k[ 2]<<16);
case 2: a+=((ub8)k[ 1]<<8);
case 1: a+=((ub8)k[ 0]);
/* case 0: nothing left to add */
}
mix64(a,b,c);
/*-------------------------------------------- report the result */
return c;
}
/*
--------------------------------------------------------------------
This works on all machines, is identical to hash() on little-endian
machines, and it is much faster than hash(), but it requires
-- that the key be an array of ub8's, and
-- that all your machines have the same endianness, and
-- that the length be the number of ub8's in the key
--------------------------------------------------------------------
*/
ub8 hash2(ub8* k,ub8 length,ub8 level)
{
ub8 a,b,c,len;
/* Set up the internal state */
len = length;
a = b = level; /* the previous hash value */
c = 0x9e3779b97f4a7c13LL; /* the golden ratio; an arbitrary value */
/*---------------------------------------- handle most of the key */
while (len >= 3)
{
a += k[0];
b += k[1];
c += k[2];
mix64(a,b,c);
k += 3; len -= 3;
}
/*-------------------------------------- handle the last 2 ub8's */
c += (length<<3);
switch(len) /* all the case statements fall through */
{
/* c is reserved for the length */
case 2: b+=k[1];
case 1: a+=k[0];
/* case 0: nothing left to add */
}
mix64(a,b,c);
/*-------------------------------------------- report the result */
return c;
}
/*
--------------------------------------------------------------------
This is identical to hash() on little-endian machines, and it is much
faster than hash(), but a little slower than hash2(), and it requires
-- that all your machines be little-endian, for example all Intel x86
chips or all VAXen. It gives wrong results on big-endian machines.
--------------------------------------------------------------------
*/
ub8 hash3(ub1* k,ub8 length,ub8 level)
{
ub8 a,b,c,len;
/* Set up the internal state */
len = length;
a = b = level; /* the previous hash value */
c = 0x9e3779b97f4a7c13LL; /* the golden ratio; an arbitrary value */
/*---------------------------------------- handle most of the key */
if (((size_t)k)&7)
{
while (len >= 24)
{
a += (k[0] +((ub8)k[ 1]<< 8)+((ub8)k[ 2]<<16)+((ub8)k[ 3]<<24)
+((ub8)k[4 ]<<32)+((ub8)k[ 5]<<40)+((ub8)k[ 6]<<48)+((ub8)k[ 7]<<56));
b += (k[8] +((ub8)k[ 9]<< 8)+((ub8)k[10]<<16)+((ub8)k[11]<<24)
+((ub8)k[12]<<32)+((ub8)k[13]<<40)+((ub8)k[14]<<48)+((ub8)k[15]<<56));
c += (k[16] +((ub8)k[17]<< 8)+((ub8)k[18]<<16)+((ub8)k[19]<<24)
+((ub8)k[20]<<32)+((ub8)k[21]<<40)+((ub8)k[22]<<48)+((ub8)k[23]<<56));
mix64(a,b,c);
k += 24; len -= 24;
}
}
else
{
while (len >= 24) /* aligned */
{
a += *(ub8 *)(k+0);
b += *(ub8 *)(k+8);
c += *(ub8 *)(k+16);
mix64(a,b,c);
k += 24; len -= 24;
}
}
/*------------------------------------- handle the last 23 bytes */
c += length;
switch(len) /* all the case statements fall through */
{
case 23: c+=((ub8)k[22]<<56);
case 22: c+=((ub8)k[21]<<48);
case 21: c+=((ub8)k[20]<<40);
case 20: c+=((ub8)k[19]<<32);
case 19: c+=((ub8)k[18]<<24);
case 18: c+=((ub8)k[17]<<16);
case 17: c+=((ub8)k[16]<<8);
/* the first byte of c is reserved for the length */
case 16: b+=((ub8)k[15]<<56);
case 15: b+=((ub8)k[14]<<48);
case 14: b+=((ub8)k[13]<<40);
case 13: b+=((ub8)k[12]<<32);
case 12: b+=((ub8)k[11]<<24);
case 11: b+=((ub8)k[10]<<16);
case 10: b+=((ub8)k[ 9]<<8);
case 9: b+=((ub8)k[ 8]);
case 8: a+=((ub8)k[ 7]<<56);
case 7: a+=((ub8)k[ 6]<<48);
case 6: a+=((ub8)k[ 5]<<40);
case 5: a+=((ub8)k[ 4]<<32);
case 4: a+=((ub8)k[ 3]<<24);
case 3: a+=((ub8)k[ 2]<<16);
case 2: a+=((ub8)k[ 1]<<8);
case 1: a+=((ub8)k[ 0]);
/* case 0: nothing left to add */
}
mix64(a,b,c);
/*-------------------------------------------- report the result */
return c;
}