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Open Source Chemistry Library
package com.actelion.research.util;
import java.util.Date;
/**
* http://burtleburtle.net/bob/c/lookup3.c
-------------------------------------------------------------------------------
lookup3.c, by Bob Jenkins, May 2006, Public Domain.
These are functions for producing 32-bit hashes for hash table lookup.
hashword(), hashlittle(), 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 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.
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().
-------------------------------------------------------------------------------
*/
public class BurtleHasher {
// The static constructor prevents many new calls
private static BurtleHasherABC abcHashlittleInteger = new BurtleHasherABC(0,0,0);
public static int hashsize(long n) {
int v = 1<<(n);
return v;
}
/**
*
* @param n number of bits set in mask.
* @return
*/
public static int hashmask(int n) {
int v = (hashsize(n)-1);
return v;
}
public static long rot(long x, long k) {
long v = (((x)<<(k)) ^ ((x)>>>(32-(k))));
return v;
}
/*
-------------------------------------------------------------------------------
mix -- mix 3 32-bit values reversibly.
This is reversible, so any information in (a,b,c) before mix() is
still in (a,b,c) after mix().
If four pairs of (a,b,c) inputs are run through mix(), or through
mix() in reverse, there are at least 32 bits of the output that
are sometimes the same for one pair and different for another pair.
This was tested for:
* pairs that differed by one bit, by two bits, in any combination
of top bits of (a,b,c), or in any combination of bottom bits of
(a,b,c).
* "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
is commonly produced by subtraction) look like a single 1-bit
difference.
* the base values were pseudorandom, all zero but one bit set, or
all zero plus a counter that starts at zero.
Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
satisfy this are
4 6 8 16 19 4
9 15 3 18 27 15
14 9 3 7 17 3
Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
for "differ" defined as + with a one-bit base and a two-bit delta. I
used http://burtleburtle.net/bob/hash/avalanche.html to choose
the operations, constants, and arrangements of the variables.
This does not achieve avalanche. There are input bits of (a,b,c)
that fail to affect some output bits of (a,b,c), especially of a. The
most thoroughly mixed value is c, but it doesn't really even achieve
avalanche in c.
This allows some parallelism. Read-after-writes are good at doubling
the number of bits affected, so the goal of mixing pulls in the opposite
direction as the goal of parallelism. I did what I could. Rotates
seem to cost as much as shifts on every machine I could lay my hands
on, and rotates are much kinder to the top and bottom bits, so I used
rotates.
-------------------------------------------------------------------------------
*/
private static void mix(BurtleHasherABC abc) {
long a = abc.a;
long b = abc.b;
long c = abc.c;
a -= c;
a ^= rot(c, 4);
c += b;
b -= a;
b ^= rot(a, 6);
a += c;
c -= b;
c ^= rot(b, 8);
b += a;
a -= c;
a ^= rot(c, 16);
c += b;
b -= a;
b ^= rot(a, 19);
a += c;
c -= b;
c ^= rot(b, 4);
b += a;
abc.a = a;
abc.b = b;
abc.c = c;
}
/*
--------------------------------------------------------------------
mix -- mix 3 64-bit values reversibly.
mix() takes 48 machine instructions, but only 24 cycles on a superscalar
machine (like Intel's new MMX architecture). It requires 4 64-bit
registers for 4::2 parallelism.
All 1-bit deltas, all 2-bit deltas, all deltas composed of top bits of
(a,b,c), and all deltas of bottom bits were tested. All deltas were
tested both on random keys and on keys that were nearly all zero.
These deltas all cause every bit of c to change between 1/3 and 2/3
of the time (well, only 113/400 to 287/400 of the time for some
2-bit delta). These deltas all cause at least 80 bits to change
among (a,b,c) when the mix is run either forward or backward (yes it
is reversible).
This implies that a hash using mix64 has no funnels. There may be
characteristics with 3-bit deltas or bigger, I didn't test for
those.
--------------------------------------------------------------------
*/
public static void mix64(BurtleHasherABC abc) {
abc.a = abc.a - abc.b;
abc.a = abc.a - abc.c;
abc.a = abc.a ^ (abc.c >> 43);
abc.b = abc.b - abc.c;
abc.b = abc.b - abc.a;
abc.b = abc.b ^ (abc.a << 9);
abc.c = abc.c - abc.a;
abc.c = abc.c - abc.b;
abc.c = abc.c ^ (abc.b >> 8);
abc.a = abc.a - abc.b;
abc.a = abc.a - abc.c;
abc.a = abc.a ^ (abc.c >> 38);
abc.b = abc.b - abc.c;
abc.b = abc.b - abc.a;
abc.b = abc.b ^ (abc.a << 23);
abc.c = abc.c - abc.a;
abc.c = abc.c - abc.b;
abc.c = abc.c ^ (abc.b >> 5);
abc.a = abc.a - abc.b;
abc.a = abc.a - abc.c;
abc.a = abc.a ^ (abc.c >> 35);
abc.b = abc.b - abc.c;
abc.b = abc.b - abc.a;
abc.b = abc.b ^ (abc.a << 49);
abc.c = abc.c - abc.a;
abc.c = abc.c - abc.b;
abc.c = abc.c ^ (abc.b >> 11);
abc.a = abc.a - abc.b;
abc.a = abc.a - abc.c;
abc.a = abc.a ^ (abc.c >> 12);
abc.b = abc.b - abc.c;
abc.b = abc.b - abc.a;
abc.b = abc.b ^ (abc.a << 18);
abc.c = abc.c - abc.a;
abc.c = abc.c - abc.b;
abc.c = abc.c ^ (abc.b >> 22);
}
/*
* -------------------------------------------------------------------------------
* final -- final mixing of 3 32-bit values (a,b,c) into c
*
* Pairs of (a,b,c) values differing in only a few bits will usually produce
* values of c that look totally different. This was tested for pairs that
* differed by one bit, by two bits, in any combination of top bits of
* (a,b,c), or in any combination of bottom bits of (a,b,c). "differ" is
* defined as +, -, ^, or ~^. For + and -, I transformed the output delta to
* a Gray code (a^(a>>1)) so a string of 1's (as is commonly produced by
* subtraction) look like a single 1-bit difference. the base values were
* pseudorandom, all zero but one bit set, or all zero plus a counter that
* starts at zero.
*
* These constants passed: 14 11 25 16 4 14 24 12 14 25 16 4 14 24 and these
* came close: 4 8 15 26 3 22 24 10 8 15 26 3 22 24 11 8 15 26 3 22 24
* -------------------------------------------------------------------------------
*/
private static void finalMix(BurtleHasherABC abc)
{
long a = abc.a;
long b = abc.b;
long c = abc.c;
c ^= b;
c -= rot(b,14);
a ^= c;
a -= rot(c,11);
b ^= a;
b -= rot(a,25);
c ^= b;
c -= rot(b,16);
a ^= c;
a -= rot(c,4);
b ^= a;
b -= rot(a,14);
c ^= b;
c -= rot(b,24);
abc.a = a;
abc.b = b;
abc.c = c;
}
/*
--------------------------------------------------------------------
This works on all machines. To be useful, it requires
-- that the key be an array of uint32_t's, and
-- that all your machines have the same endianness, and
-- that the length be the number of uint32_t's in the key
The function hashword() is identical to hashlittle() on little-endian
machines, and identical to hashbig() on big-endian machines,
except that the length has to be measured in uint32_ts rather than in
bytes. hashlittle() is more complicated than hashword() only because
hashlittle() has to dance around fitting the key bytes into registers.
--------------------------------------------------------------------
*/
public static int hashword(String w, long initval)
{
// 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 */
int length = w.length();
byte [] k = w.getBytes();
long a,b,c;
/* Set up the internal state */
a = b = c = 0xdeadbeef + (((long)length)<<2) + initval;
BurtleHasherABC abc = new BurtleHasherABC(a,b,c);
/*------------------------------------------------- handle most of the key */
int cc = 0;
while (length > 3)
{
abc.a += k[cc+0];
abc.b += k[cc+1];
abc.c += k[cc+2];
mix(abc);
length -= 3;
cc += 3;
}
/*------------------------------------------- handle the last 3 uint32_t's */
switch(length) /* all the case statements fall through */
{
case 3 : abc.c+=k[2];
case 2 : abc.b+=k[1];
case 1 : abc.a+=k[0];
finalMix(abc);
case 0: /* case 0: nothing left to add */
break;
}
/*------------------------------------------------------ report the result */
return (int)abc.c;
}
/*
-------------------------------------------------------------------------------
hashlittle() -- hash a variable-length key into a 32-bit value
k : the key (the unaligned variable-length array of bytes)
length : the length of the key, counting by bytes
initval : can be any 4-byte value
Returns a 32-bit value. Every bit of the key affects every bit of
the return value. Two keys differing by one or two bits will have
totally different hash values.
The best hash table sizes are powers of 2. There is no need to do
mod a prime (mod is sooo slow!). If you need less than 32 bits,
use a bitmask. For example, if you need only 10 bits, do
h = (h & hashmask(10));
In which case, the hash table should have hashsize(10) elements.
If you are hashing n strings (uint8_t **)k, do it like this:
for (i=0, h=0; i 12)
{
abc.a += k[cc+0];
abc.a += ((long)k[cc+1])<<8;
abc.a += ((long)k[cc+2])<<16;
abc.a += ((long)k[cc+3])<<24;
abc.b += k[cc+4];
abc.b += ((long)k[cc+5])<<8;
abc.b += ((long)k[cc+6])<<16;
abc.b += ((long)k[cc+7])<<24;
abc.c += k[cc+8];
abc.c += ((long)k[cc+9])<<8;
abc.c += ((long)k[cc+10])<<16;
abc.c += ((long)k[cc+11])<<24;
mix(abc);
length -= 12;
cc += 12;
}
/*-------------------------------- last block: affect all 32 bits of (c) */
switch(length) /* all the case statements fall through */
{
case 12: abc.c+=((long)k[cc + 11])<<24;
case 11: abc.c+=((long)k[cc + 10])<<16;
case 10: abc.c+=((long)k[cc + 9])<<8;
case 9 : abc.c+=k[8];
case 8 : abc.b+=((long)k[cc + 7])<<24;
case 7 : abc.b+=((long)k[cc + 6])<<16;
case 6 : abc.b+=((long)k[cc + 5])<<8;
case 5 : abc.b+=k[4];
case 4 : abc.a+=((long)k[cc + 3])<<24;
case 3 : abc.a+=((long)k[cc + 2])<<16;
case 2 : abc.a+=((long)k[cc + 1])<<8;
case 1 : abc.a+=k[cc + 0];
break;
case 0 : return (int)abc.c;
}
finalMix(abc);
return (int)abc.c;
}
public static int hashlittle(byte [] k, long initval) {
return hashlittle(k, initval, k.length);
}
/**
*
* @param k
* @param initval
* @param size the hash value will be calculated for k up to size fields.
* @return
*/
public static int hashlittle(byte [] k, long initval, int size) {
long a,b,c;
/* Set up the internal state */
int length = size;
a = b = c = 0xdeadbeef + ((long)length) + initval;
/* need to read the key one byte at a time */
BurtleHasherABC abc = new BurtleHasherABC(a,b,c);
int cc=0;
/*--------------- all but the last block: affect some 32 bits of (a,b,c) */
while (length > 12)
{
abc.a += k[cc+0];
abc.a += ((long)k[cc+1])<<8;
abc.a += ((long)k[cc+2])<<16;
abc.a += ((long)k[cc+3])<<24;
abc.b += k[cc+4];
abc.b += ((long)k[cc+5])<<8;
abc.b += ((long)k[cc+6])<<16;
abc.b += ((long)k[cc+7])<<24;
abc.c += k[cc+8];
abc.c += ((long)k[cc+9])<<8;
abc.c += ((long)k[cc+10])<<16;
abc.c += ((long)k[cc+11])<<24;
mix(abc);
length -= 12;
cc += 12;
}
/*-------------------------------- last block: affect all 32 bits of (c) */
switch(length) /* all the case statements fall through */
{
case 12: abc.c+=((long)k[cc + 11])<<24;
case 11: abc.c+=((long)k[cc + 10])<<16;
case 10: abc.c+=((long)k[cc + 9])<<8;
case 9 : abc.c+=k[8];
case 8 : abc.b+=((long)k[cc + 7])<<24;
case 7 : abc.b+=((long)k[cc + 6])<<16;
case 6 : abc.b+=((long)k[cc + 5])<<8;
case 5 : abc.b+=k[4];
case 4 : abc.a+=((long)k[cc + 3])<<24;
case 3 : abc.a+=((long)k[cc + 2])<<16;
case 2 : abc.a+=((long)k[cc + 1])<<8;
case 1 : abc.a+=k[cc + 0];
break;
case 0 : return (int)abc.c;
}
finalMix(abc);
return (int)abc.c;
}
/**
* MvK 10.02.2010
* @param k
* @param initval
* @return
*/
public static int hashlittle(int [] k, long initval) {
return hashlittle(k, initval, k.length);
}
/**
*
* @param k
* @param initval
* @param size the hash value will be calculated for k up to size fields.
* @return
*/
public static int hashlittle(int [] k, long initval, int size) {
long a,b,c;
/* Set up the internal state */
int length = size;
a = b = c = 0xdeadbeef + ((long)length) + initval;
/* need to read the key one byte at a time */
abcHashlittleInteger.a = a;
abcHashlittleInteger.b = b;
abcHashlittleInteger.c = c;
int cc=0;
/*--------------- all but the last block: affect some 32 bits of (a,b,c) */
while (length > 12) {
abcHashlittleInteger.a += k[cc+0];
abcHashlittleInteger.a += ((long)k[cc+1])<<8;
abcHashlittleInteger.a += ((long)k[cc+2])<<16;
abcHashlittleInteger.a += ((long)k[cc+3])<<24;
abcHashlittleInteger.b += k[cc+4];
abcHashlittleInteger.b += ((long)k[cc+5])<<8;
abcHashlittleInteger.b += ((long)k[cc+6])<<16;
abcHashlittleInteger.b += ((long)k[cc+7])<<24;
abcHashlittleInteger.c += k[cc+8];
abcHashlittleInteger.c += ((long)k[cc+9])<<8;
abcHashlittleInteger.c += ((long)k[cc+10])<<16;
abcHashlittleInteger.c += ((long)k[cc+11])<<24;
mix(abcHashlittleInteger);
length -= 12;
cc += 12;
}
/*-------------------------------- last block: affect all 32 bits of (c) */
switch(length) /* all the case statements fall through */
{
case 12: abcHashlittleInteger.c+=((long)k[cc + 11])<<24;
case 11: abcHashlittleInteger.c+=((long)k[cc + 10])<<16;
case 10: abcHashlittleInteger.c+=((long)k[cc + 9])<<8;
case 9 : abcHashlittleInteger.c+=k[8];
case 8 : abcHashlittleInteger.b+=((long)k[cc + 7])<<24;
case 7 : abcHashlittleInteger.b+=((long)k[cc + 6])<<16;
case 6 : abcHashlittleInteger.b+=((long)k[cc + 5])<<8;
case 5 : abcHashlittleInteger.b+=k[4];
case 4 : abcHashlittleInteger.a+=((long)k[cc + 3])<<24;
case 3 : abcHashlittleInteger.a+=((long)k[cc + 2])<<16;
case 2 : abcHashlittleInteger.a+=((long)k[cc + 1])<<8;
case 1 : abcHashlittleInteger.a+=k[cc + 0];
break;
case 0 : return (int)abcHashlittleInteger.c;
}
finalMix(abcHashlittleInteger);
return (int)abcHashlittleInteger.c;
}
/* used for timings */
public static void driver1()
{
int size = 256;
Date daStart = new Date();
String s = "";
for (int i=0; i>(8-j));
c[0] = hashlittle(a, hlen, m);
b[i] ^= ((k+1)<>(8-j));
d[0] = hashlittle(b, hlen, m);
// check every bit is 1, 0, set, and not set at least once
for (l=0; lz) z=k;
if (k==MAXPAIR)
{
printf("Some bit didn't change: ");
printf("%.8x %.8x %.8x %.8x %.8x %.8x ",
e[0],f[0],g[0],h[0],x[0],y[0]);
printf("i %ld j %ld m %ld len %ld\n",i,j,m,hlen);
}
if (z==MAXPAIR) {
bFin = true;
break;
}
}
if(bFin)
break;
}
if(bFin)
break;
}
if(bFin)
if (z < MAXPAIR)
{
printf("Mix success %2ld bytes %2ld initvals ",i,m);
printf("required %ld trials\n",z/2);
}
}
printf("\n");
*/
}
/* Check for reading beyond the end of the buffer and alignment problems */
public static void driver3()
{
// uint8_t q[] = "This is the time for all good men to come to the aid of their country...";
String q = "This is the time for all good men to come to the aid of their country...";
// uint8_t qq[] = "xThis is the time for all good men to come to the aid of their country...";
String qq = "xThis is the time for all good men to come to the aid of their country...";
// uint8_t qqq[] = "xxThis is the time for all good men to come to the aid of their country...";
String qqq = "xxThis is the time for all good men to come to the aid of their country...";
// uint8_t qqqq[] = "xxxThis is the time for all good men to come to the aid of their country...";
String qqqq = "xxxThis is the time for all good men to come to the aid of their country...";
long h,i,j,ref,x,y;
// uint8_t *p;
System.out.println("Endianness. These lines should all be the same (for values filled in):\n");
System.out.println("\n");
// System.out.println(hashword(q, ((q.length())-1)/4, 13));
// System.out.println(hashword(q, ((q.length())-5)/4, 13));
// System.out.println(hashword(q, ((q.length())-9)/4, 13));
System.out.println(hashword(q, 13));
String p1 = "";
String p2 = "";
p1 = q.substring(0, q.length()-1);
p2 = q.substring(0, q.length()-2);
System.out.println(hashlittle(p1, 13) + " " + hashlittle(p2, 13));
p1 = q.substring(0, q.length()-3);
p2 = q.substring(0, q.length()-4);
System.out.println(hashlittle(p1, 13) + " " + hashlittle(p2, 13));
p1 = q.substring(0, q.length()-5);
p2 = q.substring(0, q.length()-6);
System.out.println(hashlittle(p1, 13) + " " + hashlittle(p2, 13));
p1 = q.substring(0, q.length()-7);
p2 = q.substring(0, q.length()-8);
System.out.println(hashlittle(p1, 13) + " " + hashlittle(p2, 13));
p1 = q.substring(0, q.length()-9);
p2 = q.substring(0, q.length()-10);
System.out.println(hashlittle(p1, 13) + " " + hashlittle(p2, 13));
p1 = q.substring(0, q.length()-11);
p2 = q.substring(0, q.length()-12);
System.out.println(hashlittle(p1, 13) + " " + hashlittle(p2, 13));
/*
p = &qq[1];
printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
p = &qqq[2];
printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
p = &qqqq[3];
printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
*/
System.out.println("\n");
/*
for (h=0, b=buf+1; h<8; ++h, ++b)
{
for (i=0; i