Add Bob Jenkins' lookup3 32-bit and 64-bit hashes to pluginlib.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21155 a1c6a512-1295-4272-9138-f99709370657

3 files changed, 767 insertions, 0 deletions

diff --git a/apps/plugins/lib/SOURCES b/apps/plugins/lib/SOURCES
index 21a35d478a..5a6abc7848 100644
--- a/apps/plugins/lib/SOURCES
+++ b/apps/plugins/lib/SOURCES
@@ -1,4 +1,5 @@
 gcc-support.c
+jhash.c
 oldmenuapi.c
 configfile.c
 fixedpoint.c
diff --git a/apps/plugins/lib/jhash.c b/apps/plugins/lib/jhash.c
new file mode 100644
index 0000000000..780d220408
--- /dev/null
+++ b/apps/plugins/lib/jhash.c
@@ -0,0 +1,699 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2006 Bob Jenkins
+ * http://burtleburtle.net/bob/c/lookup3.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+/*
+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.
+*/
+
+#include "jhash.h"
+
+/*
+* My best guess at if you are big-endian or little-endian.  This may
+* need adjustment.
+*/
+#if defined(ROCKBOX_LITTLE_ENDIAN)
+# define HASH_LITTLE_ENDIAN 1
+# define HASH_BIG_ENDIAN 0
+#elif defined(ROCKBOX_BIG_ENDIAN)
+# define HASH_LITTLE_ENDIAN 0
+# define HASH_BIG_ENDIAN 1
+#else
+# define HASH_LITTLE_ENDIAN 0
+# define HASH_BIG_ENDIAN 0
+#endif
+
+#define hashsize(n) ((uint32_t)1<<(n))
+#define hashmask(n) (hashsize(n)-1)
+#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
+
+/*
+
+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.
+*/
+#define mix(a,b,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; \
+}
+
+/*
+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
+*/
+#define final(a,b,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); \
+}
+
+/*
+  k:       pointer to the key, an array of uint32_t
+  length:  number of elements in the key
+  initval: an initialization value
+  returns the 32-bit hash
+*/
+uint32_t hashw(const uint32_t *k, size_t length, uint32_t  initval)
+{
+    uint32_t a, b, c;
+
+    /* Set up the internal state */
+    a = b = c = 0xdeadbeef + (((uint32_t)length)<<2) + initval;
+
+    /* handle most of the key */
+    while (length > 3)
+    {
+        a += k[0];
+        b += k[1];
+        c += k[2];
+        mix(a,b,c);
+        length -= 3;
+        k += 3;
+    }
+
+    /* handle the last 3 uint32_t's */
+    switch(length) /* all the case statements fall through */
+    { 
+    case 3:
+        c+=k[2];
+    case 2:
+        b+=k[1];
+    case 1:
+        a+=k[0];
+        final(a,b,c);
+    case 0:     /* case 0: nothing left to add */
+        break;
+    }
+    /* report the result */
+    return c;
+}
+
+
+/*
+hashw2() -- same as hashw(), but take two seeds and return two
+32-bit values.  pc and pb must both be nonnull, and *pc and *pb must
+both be initialized with seeds.  If you pass in (*pb)==0, the output 
+(*pc) will be the same as the return value from hashword().
+  k:      pointer to the key, an array of uint32_t
+  length: number of elements in the key
+  pc, pb: pointers to primary and secondary initial values, also used to store
+          the hash results.
+*/
+void hashw2 (const uint32_t *k, size_t length, uint32_t *pc, uint32_t *pb)
+{
+    uint32_t a,b,c;
+
+    /* Set up the internal state */
+    a = b = c = 0xdeadbeef + ((uint32_t)(length<<2)) + *pc;
+    c += *pb;
+
+    /* handle most of the key */
+    while (length > 3)
+    {
+        a += k[0];
+        b += k[1];
+        c += k[2];
+        mix(a,b,c);
+        length -= 3;
+        k += 3;
+    }
+
+    /* handle the last 3 uint32_t's */
+    switch(length) /* all the case statements fall through */
+    { 
+    case 3:
+        c+=k[2];
+    case 2:
+        b+=k[1];
+    case 1:
+        a+=k[0];
+        final(a,b,c);
+    case 0: /* case 0: nothing left to add */
+        break;
+    }
+    /* report the result */
+    *pc=c; *pb=b;
+}
+
+
+/*
+hashs() -- hash a variable-length key into a 32-bit value
+  k:       pointer to the key, an array of bytes
+  length:  number of elements in the key
+  initval: an initialization value
+  returns the 32-bit hash
+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<n; ++i) h = hashlittle( k[i], len[i], h);
+
+By Bob Jenkins, 2006.  bob_jenkins@burtleburtle.net.  You may use this
+code any way you wish, private, educational, or commercial.  It's free.
+
+Use for hash table lookup, or anything where one collision in 2^^32 is
+acceptable.  Do NOT use for cryptographic purposes.
+*/
+
+uint32_t hashs( const void *key, size_t length, uint32_t initval)
+{
+    uint32_t a,b,c; /* internal state */
+    union { const void *ptr; size_t i; } u;/* needed for Mac Powerbook G4 */
+
+    /* Set up the internal state */
+    a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
+
+    u.ptr = key;
+#if HASH_LITTLE_ENDIAN
+    if ((u.i & 0x3) == 0) {
+        const uint32_t *k = (const uint32_t *)key;         /* read 32-bit chunks */
+
+        /* all but last block: aligned reads and affect 32 bits of (a,b,c) */
+        while (length > 12)
+        {
+            a += k[0];
+            b += k[1];
+            c += k[2];
+            mix(a,b,c);
+            length -= 12;
+            k += 3;
+        }
+
+/* handle the last (probably partial) block */
+        switch(length)
+        {
+        case 12:
+            c += k[2];
+            b += k[1];
+            a += k[0];
+            break;
+        case 11:
+            c += k[2] & 0xffffff;
+            b += k[1];
+            a += k[0];
+            break;
+        case 10:
+            c += k[2] & 0xffff;
+            b += k[1];
+            a += k[0];
+            break;
+        case 9:
+            c += k[2] & 0xff;
+            b += k[1];
+            a += k[0];
+            break;
+        case 8:
+            b += k[1];
+            a += k[0];
+            break;
+        case 7:
+            b += k[1] & 0xffffff;
+            a += k[0];
+            break;
+        case 6:
+            b += k[1] & 0xffff;
+            a += k[0];
+            break;
+        case 5:
+            b += k[1] & 0xff;
+            a += k[0];
+            break;
+        case 4:
+            a += k[0];
+            break;
+        case 3:
+            a += k[0] & 0xffffff;
+            break;
+        case 2 :
+            a += k[0] & 0xffff;
+            break;
+        case 1:
+            a += k[0] & 0xff;
+            break;
+        case 0: 
+            return c; /* zero length strings require no mixing */
+        }
+
+    } else if ((u.i & 0x1) == 0) {
+        const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */
+        const uint8_t  *k8;
+
+    /* all but last block: aligned reads and different mixing */
+        while (length > 12)
+        {
+            a += k[0] + (((uint32_t)k[1])<<16);
+            b += k[2] + (((uint32_t)k[3])<<16);
+            c += k[4] + (((uint32_t)k[5])<<16);
+            mix(a,b,c);
+            length -= 12;
+            k += 6;
+        }
+
+        /* handle the last (probably partial) block */
+        k8 = (const uint8_t *)k;
+        switch(length)
+        {
+        case 12:
+            c += k[4] + (((uint32_t)k[5])<<16);
+            b += k[2] + (((uint32_t)k[3])<<16);
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 11:
+            c += ((uint32_t)k8[10])<<16; /* fall through */
+        case 10:
+            c += k[4];
+            b += k[2] + (((uint32_t)k[3])<<16);
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 9:
+            c += k8[8]; /* fall through */
+        case 8:
+            b += k[2] + (((uint32_t)k[3])<<16);
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 7:
+            b += ((uint32_t)k8[6])<<16; /* fall through */
+        case 6:
+            b += k[2];
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 5:
+            b += k8[4]; /* fall through */
+        case 4:
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 3:
+            a += ((uint32_t)k8[2])<<16;      /* fall through */
+        case 2:
+            a += k[0];
+            break;
+        case 1:
+            a += k8[0];
+            break;
+        case 0:
+            return c; /* zero length requires no mixing */
+        }
+
+    } else
+#endif
+    { /* need to read the key one byte at a time */
+        const uint8_t *k = (const uint8_t *)key;
+
+        /* all but the last block: affect some 32 bits of (a,b,c) */
+        while (length > 12)
+        {
+            a += k[0];
+            a += ((uint32_t)k[1])<<8;
+            a += ((uint32_t)k[2])<<16;
+            a += ((uint32_t)k[3])<<24;
+            b += k[4];
+            b += ((uint32_t)k[5])<<8;
+            b += ((uint32_t)k[6])<<16;
+            b += ((uint32_t)k[7])<<24;
+            c += k[8];
+            c += ((uint32_t)k[9])<<8;
+            c += ((uint32_t)k[10])<<16;
+            c += ((uint32_t)k[11])<<24;
+            mix(a,b,c);
+            length -= 12;
+            k += 12;
+        }
+
+        /* last block: affect all 32 bits of (c) */
+        switch(length) /* all the case statements fall through */
+        {
+        case 12:
+            c += ((uint32_t)k[11])<<24;
+        case 11:
+            c += ((uint32_t)k[10])<<16;
+        case 10:
+            c += ((uint32_t)k[9])<<8;
+        case 9:
+            c += k[8];
+        case 8:
+            b += ((uint32_t)k[7])<<24;
+        case 7:
+            b += ((uint32_t)k[6])<<16;
+        case 6:
+            b += ((uint32_t)k[5])<<8;
+        case 5:
+            b += k[4];
+        case 4:
+            a += ((uint32_t)k[3])<<24;
+        case 3:
+            a += ((uint32_t)k[2])<<16;
+        case 2:
+            a += ((uint32_t)k[1])<<8;
+        case 1:
+            a +=k [0];
+            break;
+        case 0:
+            return c;
+        }
+    }
+
+    final(a,b,c);
+    return c;
+}
+
+
+/*
+hashs2: return 2 32-bit hash values
+  k:       pointer to the key, an array of bytes
+  length: number of elements in the key
+  pc, pb: pointers to primary and secondary initial values, also used to store
+          the hash results.
+* This is identical to hashlittle(), except it returns two 32-bit hash
+* values instead of just one.  This is good enough for hash table
+* lookup with 2^^64 buckets, or if you want a second hash if you're not
+* happy with the first, or if you want a probably-unique 64-bit ID for
+* the key.  *pc is better mixed than *pb, so use *pc first.  If you want
+* a 64-bit value do something like "*pc + (((uint64_t)*pb)<<32)".
+*/
+void hashs2(const void *key, size_t length, uint32_t *pc, uint32_t *pb)
+{
+    uint32_t a, b, c; /* internal state */
+    union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */
+
+    /* Set up the internal state */
+    a = b = c = 0xdeadbeef + ((uint32_t)length) + *pc;
+    c += *pb;
+
+    u.ptr = key;
+#if HASH_LITTLE_ENDIAN
+    if (((u.i & 0x3) == 0)) {
+        const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
+
+        /* all but last block: aligned reads and affect 32 bits of (a,b,c) */
+        while (length > 12)
+        {
+            a += k[0];
+            b += k[1];
+            c += k[2];
+            mix(a,b,c);
+            length -= 12;
+            k += 3;
+        }
+
+/* handle the last (probably partial) block */
+        switch(length)
+        {
+        case 12:
+            c += k[2];
+            b += k[1];
+            a += k[0];
+            break;
+        case 11:
+            c += k[2] & 0xffffff;
+            b += k[1];
+            a += k[0];
+            break;
+        case 10:
+            c += k[2] & 0xffff;
+            b += k[1];
+            a += k[0];
+            break;
+        case 9:
+            c += k[2] & 0xff;
+            b += k[1];
+            a += k[0];
+            break;
+        case 8:
+            b += k[1];
+            a += k[0];
+            break;
+        case 7:
+            b += k[1] & 0xffffff;
+            a += k[0];
+            break;
+        case 6:
+            b += k[1] & 0xffff;
+            a += k[0];
+            break;
+        case 5:
+            b += k[1] & 0xff;
+            a += k[0];
+            break;
+        case 4:
+            a += k[0];
+            break;
+        case 3:
+            a += k[0] & 0xffffff;
+            break;
+        case 2:
+            a += k[0] & 0xffff;
+            break;
+        case 1:
+            a += k[0] & 0xff;
+            break;
+        case 0:
+            *pc=c;
+            *pb=b;
+            return; /* zero length strings require no mixing */
+        }
+    } else if (((u.i & 0x1) == 0)) {
+        const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */
+        const uint8_t  *k8;
+
+        /* all but last block: aligned reads and different mixing */
+        while (length > 12)
+        {
+            a += k[0] + (((uint32_t)k[1])<<16);
+            b += k[2] + (((uint32_t)k[3])<<16);
+            c += k[4] + (((uint32_t)k[5])<<16);
+            mix(a,b,c);
+            length -= 12;
+            k += 6;
+        }
+
+        /* handle the last (probably partial) block */
+        k8 = (const uint8_t *)k;
+        switch(length)
+        {
+        case 12:
+            c += k[4] + (((uint32_t)k[5])<<16);
+            b += k[2] + (((uint32_t)k[3])<<16);
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 11:
+            c += ((uint32_t)k8[10])<<16; /* fall through */
+        case 10:
+            c += k[4];
+            b += k[2] + (((uint32_t)k[3])<<16);
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 9:
+            c += k8[8]; /* fall through */
+        case 8:
+            b += k[2] + (((uint32_t)k[3])<<16);
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 7:
+            b += ((uint32_t)k8[6])<<16; /* fall through */
+        case 6:
+            b += k[2];
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 5:
+            b += k8[4]; /* fall through */
+        case 4:
+            a += k[0] + (((uint32_t)k[1])<<16);
+            break;
+        case 3:
+            a += ((uint32_t)k8[2])<<16; /* fall through */
+        case 2:
+            a += k[0];
+            break;
+        case 1:
+            a += k8[0];
+            break;
+        case 0:
+            *pc=c;
+            *pb=b;
+            return; /* zero length strings require no mixing */
+        }
+    } else
+#endif
+    { /* need to read the key one byte at a time */
+        const uint8_t *k = (const uint8_t *)key;
+
+        /* all but the last block: affect some 32 bits of (a,b,c) */
+        while (length > 12)
+        {
+            a += k[0];
+            a += ((uint32_t)k[1])<<8;
+            a += ((uint32_t)k[2])<<16;
+            a += ((uint32_t)k[3])<<24;
+            b += k[4];
+            b += ((uint32_t)k[5])<<8;
+            b += ((uint32_t)k[6])<<16;
+            b += ((uint32_t)k[7])<<24;
+            c += k[8];
+            c += ((uint32_t)k[9])<<8;
+            c += ((uint32_t)k[10])<<16;
+            c += ((uint32_t)k[11])<<24;
+            mix(a,b,c);
+            length -= 12;
+            k += 12;
+        }
+
+        /* last block: affect all 32 bits of (c) */
+        switch(length) /* all the case statements fall through */
+        {
+        case 12:
+            c += ((uint32_t)k[11]) << 24;
+        case 11:
+            c += ((uint32_t)k[10]) << 16;
+        case 10:
+            c += ((uint32_t)k[9]) << 8;
+        case 9:
+            c += k[8];
+        case 8:
+            b += ((uint32_t)k[7]) << 24;
+        case 7:
+            b += ((uint32_t)k[6]) << 16;
+        case 6:
+            b += ((uint32_t)k[5]) << 8;
+        case 5:
+            b += k[4];
+        case 4:
+            a += ((uint32_t)k[3]) << 24;
+        case 3:
+            a += ((uint32_t)k[2]) << 16;
+        case 2:
+            a += ((uint32_t)k[1]) << 8;
+        case 1:
+            a += k[0];
+            break;
+        case 0:
+            *pc=c;
+            *pb=b;
+            return; /* zero length strings require no mixing */
+        }
+    }
+
+    final(a,b,c);
+    *pc=c;
+    *pb=b;
+}
diff --git a/apps/plugins/lib/jhash.h b/apps/plugins/lib/jhash.h
new file mode 100644
index 0000000000..97d1ac3d93
--- /dev/null
+++ b/apps/plugins/lib/jhash.h
@@ -0,0 +1,67 @@
+/***************************************************************************
+*             __________               __   ___.
+*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+*                     \/            \/     \/    \/            \/
+* $Id$
+*
+* Copyright (C) 2009 by Andrew Mahone
+*
+* jhash.c headers
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public License
+* as published by the Free Software Foundation; either version 2
+* of the License, or (at your option) any later version.
+*
+* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+* KIND, either express or implied.
+*
+****************************************************************************/
+
+#ifndef _LIB_JHASH_H_
+#define _LIB_JHASH_H_
+#include <inttypes.h>     /* defines uint32_t etc */
+#include <sys/types.h>
+#include <plugin.h>
+
+/*
+hashw() -- hash an array of uint32_t into a 32-bit value
+  k:       pointer to the key, an array of uint32_t
+  length:  number of elements in the key
+  initval: an initialization value
+  returns the 32-bit hash
+*/
+uint32_t hashw(const uint32_t *k, size_t length, uint32_t  initval);
+
+/*
+hashw() -- hash an array of uint32_t into two 32-bit values
+(*pc) will be the same as the return value from hashword().
+  k:      pointer to the key, an array of uint32_t
+  length: number of elements in the key
+  pc, pb: pointers to primary and secondary initial values, also used to store
+          the hash results.
+*/
+void hashw2 (const uint32_t *k, size_t length, uint32_t *pc, uint32_t *pb);
+
+/*
+hashs() -- hash an array of bytes into a 32-bit value
+  k:       pointer to the key, an array of bytes
+  length:  number of elements in the key
+  initval: an initialization value
+  returns the 32-bit hash
+*/
+uint32_t hashs( const void *key, size_t length, uint32_t initval);
+
+/*
+hashs2() -- hash an array of bytes into two 32-bit values
+  k:       pointer to the key, an array of bytes
+  length: number of elements in the key
+  pc, pb: pointers to primary and secondary initial values, also used to store
+          the hash results.
+*/
+void hashs2(const void *key, size_t length, uint32_t *pc, uint32_t *pb);
+#endif
+