--- /dev/null
+/*
+-------------------------------------------------------------------------------
+lookup3.c, by Bob Jenkins, May 2006, Public Domain.
+
+These are functions for producing 32-bit hashes for hash table lookup.
+hash_word(), 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 hash_word(). 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.
+-------------------------------------------------------------------------------
+*/
+//#define SELF_TEST 1
+
+#if 0
+#include <stdio.h> /* defines printf for tests */
+#include <time.h> /* defines time_t for timings in the test */
+#include <stdint.h> /* defines uint32_t etc */
+#include <sys/param.h> /* attempt to define endianness */
+#endif
+
+#include "hash.h"
+#ifdef linux
+# include <endian.h> /* attempt to define endianness */
+#endif
+
+/*
+ * My best guess at if you are big-endian or little-endian. This may
+ * need adjustment.
+ */
+#if (defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && \
+ __BYTE_ORDER == __LITTLE_ENDIAN) || \
+ (defined(i386) || defined(__i386__) || defined(__i486__) || \
+ defined(__i586__) || defined(__i686__) || defined(vax) || defined(MIPSEL))
+# define HASH_LITTLE_ENDIAN 1
+# define HASH_BIG_ENDIAN 0
+#elif (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && \
+ __BYTE_ORDER == __BIG_ENDIAN) || \
+ (defined(sparc) || defined(POWERPC) || defined(mc68000) || defined(sel))
+# define HASH_LITTLE_ENDIAN 0
+# define HASH_BIG_ENDIAN 1
+#else
+# error Unknown endian
+#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); \
+}
+
+/*
+--------------------------------------------------------------------
+ This works on all machines. To be useful, it requires
+ -- that the key be an array of uint32_t's, and
+ -- that the length be the number of uint32_t's in the key
+
+ The function hash_word() 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 hash_word() only because
+ hashlittle() has to dance around fitting the key bytes into registers.
+--------------------------------------------------------------------
+*/
+uint32_t hash_u32(
+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 */
+{
+ 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;
+}
+
+/*
+-------------------------------------------------------------------------------
+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
+ val2 : IN: can be any 4-byte value OUT: second 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. Note that the return value is better
+mixed than val2, so use that first.
+
+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.
+-------------------------------------------------------------------------------
+*/
+
+static uint32_t hashlittle( const void *key, size_t length, uint32_t *val2 )
+{
+ 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) + *val2;
+
+ u.ptr = key;
+ if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
+ const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
+#ifdef VALGRIND
+ const uint8_t *k8;
+#endif
+
+ /*------ 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 */
+ /*
+ * "k[2]&0xffffff" actually reads beyond the end of the string, but
+ * then masks off the part it's not allowed to read. Because the
+ * string is aligned, the masked-off tail is in the same word as the
+ * rest of the string. Every machine with memory protection I've seen
+ * does it on word boundaries, so is OK with this. But VALGRIND will
+ * still catch it and complain. The masking trick does make the hash
+ * noticably faster for short strings (like English words).
+ */
+#ifndef VALGRIND
+
+ 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 /* make valgrind happy */
+
+ k8 = (const uint8_t *)k;
+ switch(length)
+ {
+ case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+ case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
+ case 10: c+=((uint32_t)k8[9])<<8; /* fall through */
+ case 9 : c+=k8[8]; /* fall through */
+ case 8 : b+=k[1]; a+=k[0]; break;
+ case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
+ case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */
+ case 5 : b+=k8[4]; /* fall through */
+ case 4 : a+=k[0]; break;
+ case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
+ case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */
+ case 1 : a+=k8[0]; break;
+ case 0 : return c;
+ }
+
+#endif /* !valgrind */
+
+ } else if (HASH_LITTLE_ENDIAN && ((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 { /* 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);
+ *val2 = b;
+ return c;
+}
+
+/*
+ * hashbig():
+ * This is the same as hash_word() on big-endian machines. It is different
+ * from hashlittle() on all machines. hashbig() takes advantage of
+ * big-endian byte ordering.
+ */
+static uint32_t hashbig( const void *key, size_t length, uint32_t *val2)
+{
+ uint32_t a,b,c;
+ union { const void *ptr; size_t i; } u; /* to cast key to (size_t) happily */
+
+ /* Set up the internal state */
+ a = b = c = 0xdeadbeef + ((uint32_t)length) + *val2;
+
+ u.ptr = key;
+ if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) {
+ const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
+#ifdef VALGRIND
+ const uint8_t *k8;
+#endif
+
+ /*------ 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 */
+ /*
+ * "k[2]<<8" actually reads beyond the end of the string, but
+ * then shifts out the part it's not allowed to read. Because the
+ * string is aligned, the illegal read is in the same word as the
+ * rest of the string. Every machine with memory protection I've seen
+ * does it on word boundaries, so is OK with this. But VALGRIND will
+ * still catch it and complain. The masking trick does make the hash
+ * noticably faster for short strings (like English words).
+ */
+#ifndef VALGRIND
+
+ switch(length)
+ {
+ case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+ case 11: c+=k[2]&0xffffff00; b+=k[1]; a+=k[0]; break;
+ case 10: c+=k[2]&0xffff0000; b+=k[1]; a+=k[0]; break;
+ case 9 : c+=k[2]&0xff000000; b+=k[1]; a+=k[0]; break;
+ case 8 : b+=k[1]; a+=k[0]; break;
+ case 7 : b+=k[1]&0xffffff00; a+=k[0]; break;
+ case 6 : b+=k[1]&0xffff0000; a+=k[0]; break;
+ case 5 : b+=k[1]&0xff000000; a+=k[0]; break;
+ case 4 : a+=k[0]; break;
+ case 3 : a+=k[0]&0xffffff00; break;
+ case 2 : a+=k[0]&0xffff0000; break;
+ case 1 : a+=k[0]&0xff000000; break;
+ case 0 : return c; /* zero length strings require no mixing */
+ }
+
+#else /* make valgrind happy */
+
+ k8 = (const uint8_t *)k;
+ switch(length) /* all the case statements fall through */
+ {
+ case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+ case 11: c+=((uint32_t)k8[10])<<8; /* fall through */
+ case 10: c+=((uint32_t)k8[9])<<16; /* fall through */
+ case 9 : c+=((uint32_t)k8[8])<<24; /* fall through */
+ case 8 : b+=k[1]; a+=k[0]; break;
+ case 7 : b+=((uint32_t)k8[6])<<8; /* fall through */
+ case 6 : b+=((uint32_t)k8[5])<<16; /* fall through */
+ case 5 : b+=((uint32_t)k8[4])<<24; /* fall through */
+ case 4 : a+=k[0]; break;
+ case 3 : a+=((uint32_t)k8[2])<<8; /* fall through */
+ case 2 : a+=((uint32_t)k8[1])<<16; /* fall through */
+ case 1 : a+=((uint32_t)k8[0])<<24; break;
+ case 0 : return c;
+ }
+
+#endif /* !VALGRIND */
+
+ } else { /* 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 += ((uint32_t)k[0])<<24;
+ a += ((uint32_t)k[1])<<16;
+ a += ((uint32_t)k[2])<<8;
+ a += ((uint32_t)k[3]);
+ b += ((uint32_t)k[4])<<24;
+ b += ((uint32_t)k[5])<<16;
+ b += ((uint32_t)k[6])<<8;
+ b += ((uint32_t)k[7]);
+ c += ((uint32_t)k[8])<<24;
+ c += ((uint32_t)k[9])<<16;
+ c += ((uint32_t)k[10])<<8;
+ c += ((uint32_t)k[11]);
+ 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+=k[11];
+ case 11: c+=((uint32_t)k[10])<<8;
+ case 10: c+=((uint32_t)k[9])<<16;
+ case 9 : c+=((uint32_t)k[8])<<24;
+ case 8 : b+=k[7];
+ case 7 : b+=((uint32_t)k[6])<<8;
+ case 6 : b+=((uint32_t)k[5])<<16;
+ case 5 : b+=((uint32_t)k[4])<<24;
+ case 4 : a+=k[3];
+ case 3 : a+=((uint32_t)k[2])<<8;
+ case 2 : a+=((uint32_t)k[1])<<16;
+ case 1 : a+=((uint32_t)k[0])<<24;
+ break;
+ case 0 : return c;
+ }
+ }
+
+ final(a,b,c);
+ *val2 = b;
+ return c;
+}
+
+/* I basically use hashlittle here, but use native endian within each
+ * element. This delivers least-surprise: hash such as "int arr[] = {
+ * 1, 2 }; hash_stable(arr, 2, 0);" will be the same on big and little
+ * endian machines, even though a bytewise hash wouldn't be. */
+uint64_t hash64_stable_64(const void *key, size_t n, uint64_t base)
+{
+ const uint64_t *k = key;
+ uint32_t a,b,c;
+
+ /* Set up the internal state */
+ a = b = c = 0xdeadbeef + ((uint32_t)n*8) + (base >> 32) + base;
+
+ while (n > 3) {
+ a += (uint32_t)k[0];
+ b += (uint32_t)(k[0] >> 32);
+ c += (uint32_t)k[1];
+ mix(a,b,c);
+ a += (uint32_t)(k[1] >> 32);
+ b += (uint32_t)k[2];
+ c += (uint32_t)(k[2] >> 32);
+ mix(a,b,c);
+ n -= 3;
+ k += 3;
+ }
+ switch (n) {
+ case 2:
+ a += (uint32_t)k[0];
+ b += (uint32_t)(k[0] >> 32);
+ c += (uint32_t)k[1];
+ mix(a,b,c);
+ a += (uint32_t)(k[1] >> 32);
+ break;
+ case 1:
+ a += (uint32_t)k[0];
+ b += (uint32_t)(k[0] >> 32);
+ break;
+ case 0:
+ return c;
+ }
+ final(a,b,c);
+ return ((uint64_t)b << 32) | c;
+}
+
+uint64_t hash64_stable_32(const void *key, size_t n, uint64_t base)
+{
+ const uint32_t *k = key;
+ uint32_t a,b,c;
+
+ /* Set up the internal state */
+ a = b = c = 0xdeadbeef + ((uint32_t)n*4) + (base >> 32) + base;
+
+ while (n > 3) {
+ a += k[0];
+ b += k[1];
+ c += k[2];
+ mix(a,b,c);
+
+ n -= 3;
+ k += 3;
+ }
+ switch (n) {
+ case 2:
+ b += (uint32_t)k[1];
+ case 1:
+ a += (uint32_t)k[0];
+ break;
+ case 0:
+ return c;
+ }
+ final(a,b,c);
+ return ((uint64_t)b << 32) | c;
+}
+
+uint64_t hash64_stable_16(const void *key, size_t n, uint64_t base)
+{
+ const uint16_t *k = key;
+ uint32_t a,b,c;
+
+ /* Set up the internal state */
+ a = b = c = 0xdeadbeef + ((uint32_t)n*2) + (base >> 32) + base;
+
+ while (n > 6) {
+ a += (uint32_t)k[0] + ((uint32_t)k[1] << 16);
+ b += (uint32_t)k[2] + ((uint32_t)k[3] << 16);
+ c += (uint32_t)k[4] + ((uint32_t)k[5] << 16);
+ mix(a,b,c);
+
+ n -= 6;
+ k += 6;
+ }
+
+ switch (n) {
+ case 5:
+ c += (uint32_t)k[4];
+ case 4:
+ b += ((uint32_t)k[3] << 16);
+ case 3:
+ b += (uint32_t)k[2];
+ case 2:
+ a += ((uint32_t)k[1] << 16);
+ case 1:
+ a += (uint32_t)k[0];
+ break;
+ case 0:
+ return c;
+ }
+ final(a,b,c);
+ return ((uint64_t)b << 32) | c;
+}
+
+uint64_t hash64_stable_8(const void *key, size_t n, uint64_t base)
+{
+ uint32_t b32 = base + (base >> 32);
+ uint32_t lower = hashlittle(key, n, &b32);
+
+ return ((uint64_t)b32 << 32) | lower;
+}
+
+uint32_t hash_any(const void *key, size_t length, uint32_t base)
+{
+ if (HASH_BIG_ENDIAN)
+ return hashbig(key, length, &base);
+ else
+ return hashlittle(key, length, &base);
+}
+
+uint32_t hash_stable_64(const void *key, size_t n, uint32_t base)
+{
+ return hash64_stable_64(key, n, base);
+}
+
+uint32_t hash_stable_32(const void *key, size_t n, uint32_t base)
+{
+ return hash64_stable_32(key, n, base);
+}
+
+uint32_t hash_stable_16(const void *key, size_t n, uint32_t base)
+{
+ return hash64_stable_16(key, n, base);
+}
+
+uint32_t hash_stable_8(const void *key, size_t n, uint32_t base)
+{
+ return hashlittle(key, n, &base);
+}
+
+/* Jenkins' lookup8 is a 64 bit hash, but he says it's obsolete. Use
+ * the plain one and recombine into 64 bits. */
+uint64_t hash64_any(const void *key, size_t length, uint64_t base)
+{
+ uint32_t b32 = base + (base >> 32);
+ uint32_t lower;
+
+ if (HASH_BIG_ENDIAN)
+ lower = hashbig(key, length, &b32);
+ else
+ lower = hashlittle(key, length, &b32);
+
+ return ((uint64_t)b32 << 32) | lower;
+}
+
+#ifdef SELF_TEST
+
+/* used for timings */
+void driver1()
+{
+ uint8_t buf[256];
+ uint32_t i;
+ uint32_t h=0;
+ time_t a,z;
+
+ time(&a);
+ for (i=0; i<256; ++i) buf[i] = 'x';
+ for (i=0; i<1; ++i)
+ {
+ h = hashlittle(&buf[0],1,h);
+ }
+ time(&z);
+ if (z-a > 0) printf("time %d %.8x\n", z-a, h);
+}
+
+/* check that every input bit changes every output bit half the time */
+#define HASHSTATE 1
+#define HASHLEN 1
+#define MAXPAIR 60
+#define MAXLEN 70
+void driver2()
+{
+ uint8_t qa[MAXLEN+1], qb[MAXLEN+2], *a = &qa[0], *b = &qb[1];
+ uint32_t c[HASHSTATE], d[HASHSTATE], i=0, j=0, k, l, m=0, z;
+ uint32_t e[HASHSTATE],f[HASHSTATE],g[HASHSTATE],h[HASHSTATE];
+ uint32_t x[HASHSTATE],y[HASHSTATE];
+ uint32_t hlen;
+
+ printf("No more than %d trials should ever be needed \n",MAXPAIR/2);
+ for (hlen=0; hlen < MAXLEN; ++hlen)
+ {
+ z=0;
+ for (i=0; i<hlen; ++i) /*----------------------- for each input byte, */
+ {
+ for (j=0; j<8; ++j) /*------------------------ for each input bit, */
+ {
+ for (m=1; m<8; ++m) /*------------ for serveral possible initvals, */
+ {
+ for (l=0; l<HASHSTATE; ++l)
+ e[l]=f[l]=g[l]=h[l]=x[l]=y[l]=~((uint32_t)0);
+
+ /*---- check that every output bit is affected by that input bit */
+ for (k=0; k<MAXPAIR; k+=2)
+ {
+ uint32_t finished=1;
+ /* keys have one bit different */
+ for (l=0; l<hlen+1; ++l) {a[l] = b[l] = (uint8_t)0;}
+ /* have a and b be two keys differing in only one bit */
+ a[i] ^= (k<<j);
+ a[i] ^= (k>>(8-j));
+ c[0] = hashlittle(a, hlen, m);
+ b[i] ^= ((k+1)<<j);
+ 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; l<HASHSTATE; ++l)
+ {
+ e[l] &= (c[l]^d[l]);
+ f[l] &= ~(c[l]^d[l]);
+ g[l] &= c[l];
+ h[l] &= ~c[l];
+ x[l] &= d[l];
+ y[l] &= ~d[l];
+ if (e[l]|f[l]|g[l]|h[l]|x[l]|y[l]) finished=0;
+ }
+ if (finished) break;
+ }
+ if (k>z) 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 %d j %d m %d len %d\n", i, j, m, hlen);
+ }
+ if (z==MAXPAIR) goto done;
+ }
+ }
+ }
+ done:
+ if (z < MAXPAIR)
+ {
+ printf("Mix success %2d bytes %2d initvals ",i,m);
+ printf("required %d trials\n", z/2);
+ }
+ }
+ printf("\n");
+}
+
+/* Check for reading beyond the end of the buffer and alignment problems */
+void driver3()
+{
+ uint8_t buf[MAXLEN+20], *b;
+ uint32_t len;
+ uint8_t q[] = "This is the time for all good men to come to the aid of their country...";
+ uint32_t h;
+ uint8_t qq[] = "xThis is the time for all good men to come to the aid of their country...";
+ uint32_t i;
+ uint8_t qqq[] = "xxThis is the time for all good men to come to the aid of their country...";
+ uint32_t j;
+ uint8_t qqqq[] = "xxxThis is the time for all good men to come to the aid of their country...";
+ uint32_t ref,x,y;
+ uint8_t *p;
+
+ printf("Endianness. These lines should all be the same (for values filled in):\n");
+ printf("%.8x %.8x %.8x\n",
+ hash_word((const uint32_t *)q, (sizeof(q)-1)/4, 13),
+ hash_word((const uint32_t *)q, (sizeof(q)-5)/4, 13),
+ hash_word((const uint32_t *)q, (sizeof(q)-9)/4, 13));
+ p = q;
+ 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 = &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));
+ printf("\n");
+
+ /* check that hashlittle2 and hashlittle produce the same results */
+ i=47; j=0;
+ hashlittle2(q, sizeof(q), &i, &j);
+ if (hashlittle(q, sizeof(q), 47) != i)
+ printf("hashlittle2 and hashlittle mismatch\n");
+
+ /* check that hash_word2 and hash_word produce the same results */
+ len = 0xdeadbeef;
+ i=47, j=0;
+ hash_word2(&len, 1, &i, &j);
+ if (hash_word(&len, 1, 47) != i)
+ printf("hash_word2 and hash_word mismatch %x %x\n",
+ i, hash_word(&len, 1, 47));
+
+ /* check hashlittle doesn't read before or after the ends of the string */
+ for (h=0, b=buf+1; h<8; ++h, ++b)
+ {
+ for (i=0; i<MAXLEN; ++i)
+ {
+ len = i;
+ for (j=0; j<i; ++j) *(b+j)=0;
+
+ /* these should all be equal */
+ ref = hashlittle(b, len, (uint32_t)1);
+ *(b+i)=(uint8_t)~0;
+ *(b-1)=(uint8_t)~0;
+ x = hashlittle(b, len, (uint32_t)1);
+ y = hashlittle(b, len, (uint32_t)1);
+ if ((ref != x) || (ref != y))
+ {
+ printf("alignment error: %.8x %.8x %.8x %d %d\n",ref,x,y,
+ h, i);
+ }
+ }
+ }
+}
+
+/* check for problems with nulls */
+ void driver4()
+{
+ uint8_t buf[1];
+ uint32_t h,i,state[HASHSTATE];
+
+
+ buf[0] = ~0;
+ for (i=0; i<HASHSTATE; ++i) state[i] = 1;
+ printf("These should all be different\n");
+ for (i=0, h=0; i<8; ++i)
+ {
+ h = hashlittle(buf, 0, h);
+ printf("%2ld 0-byte strings, hash is %.8x\n", i, h);
+ }
+}
+
+
+int main()
+{
+ driver1(); /* test that the key is hashed: used for timings */
+ driver2(); /* test that whole key is hashed thoroughly */
+ driver3(); /* test that nothing but the key is hashed */
+ driver4(); /* test hashing multiple buffers (all buffers are null) */
+ return 1;
+}
+
+#endif /* SELF_TEST */
--- /dev/null
+#ifndef CCAN_HASH_H
+#define CCAN_HASH_H
+#include <stdint.h>
+#include <stdlib.h>
+#include "config.h"
+
+/* Stolen mostly from: lookup3.c, by Bob Jenkins, May 2006, Public Domain.
+ *
+ * http://burtleburtle.net/bob/c/lookup3.c
+ */
+
+/**
+ * hash - fast hash of an array for internal use
+ * @p: the array or pointer to first element
+ * @num: the number of elements to hash
+ * @base: the base number to roll into the hash (usually 0)
+ *
+ * The memory region pointed to by p is combined with the base to form
+ * a 32-bit hash.
+ *
+ * This hash will have different results on different machines, so is
+ * only useful for internal hashes (ie. not hashes sent across the
+ * network or saved to disk).
+ *
+ * It may also change with future versions: it could even detect at runtime
+ * what the fastest hash to use is.
+ *
+ * See also: hash64, hash_stable.
+ *
+ * Example:
+ * #include "hash/hash.h"
+ * #include <err.h>
+ * #include <stdio.h>
+ *
+ * // Simple demonstration: idential strings will have the same hash, but
+ * // two different strings will probably not.
+ * int main(int argc, char *argv[])
+ * {
+ * uint32_t hash1, hash2;
+ *
+ * if (argc != 3)
+ * err(1, "Usage: %s <string1> <string2>", argv[0]);
+ *
+ * hash1 = hash(argv[1], strlen(argv[1]), 0);
+ * hash2 = hash(argv[2], strlen(argv[2]), 0);
+ * printf("Hash is %s\n", hash1 == hash2 ? "same" : "different");
+ * return 0;
+ * }
+ */
+#define hash(p, num, base) hash_any((p), (num)*sizeof(*(p)), (base))
+
+/**
+ * hash_stable - hash of an array for external use
+ * @p: the array or pointer to first element
+ * @num: the number of elements to hash
+ * @base: the base number to roll into the hash (usually 0)
+ *
+ * The array of simple integer types pointed to by p is combined with
+ * the base to form a 32-bit hash.
+ *
+ * This hash will have the same results on different machines, so can
+ * be used for external hashes (ie. hashes sent across the network or
+ * saved to disk). The results will not change in future versions of
+ * this module.
+ *
+ * Note that it is only legal to hand an array of simple integer types
+ * to this hash (ie. char, uint16_t, int64_t, etc). In these cases,
+ * the same values will have the same hash result, even though the
+ * memory representations of integers depend on the machine
+ * endianness.
+ *
+ * See also:
+ * hash64_stable
+ *
+ * Example:
+ * #include "hash/hash.h"
+ * #include <err.h>
+ * #include <stdio.h>
+ *
+ * int main(int argc, char *argv[])
+ * {
+ * if (argc != 2)
+ * err(1, "Usage: %s <string-to-hash>", argv[0]);
+ *
+ * printf("Hash stable result is %u\n",
+ * hash_stable(argv[1], strlen(argv[1]), 0));
+ * return 0;
+ * }
+ */
+#define hash_stable(p, num, base) \
+ (EXPR_BUILD_ASSERT(sizeof(*(p)) == 8 || sizeof(*(p)) == 4 \
+ || sizeof(*(p)) == 2 || sizeof(*(p)) == 1) + \
+ sizeof(*(p)) == 8 ? hash_stable_64((p), (num), (base)) \
+ : sizeof(*(p)) == 4 ? hash_stable_32((p), (num), (base)) \
+ : sizeof(*(p)) == 2 ? hash_stable_16((p), (num), (base)) \
+ : hash_stable_8((p), (num), (base)))
+
+/**
+ * hash_u32 - fast hash an array of 32-bit values for internal use
+ * @key: the array of uint32_t
+ * @num: the number of elements to hash
+ * @base: the base number to roll into the hash (usually 0)
+ *
+ * The array of uint32_t pointed to by @key is combined with the base
+ * to form a 32-bit hash. This is 2-3 times faster than hash() on small
+ * arrays, but the advantage vanishes over large hashes.
+ *
+ * This hash will have different results on different machines, so is
+ * only useful for internal hashes (ie. not hashes sent across the
+ * network or saved to disk).
+ */
+uint32_t hash_u32(const uint32_t *key, size_t num, uint32_t base);
+
+/**
+ * hash_string - very fast hash of an ascii string
+ * @str: the nul-terminated string
+ *
+ * The string is hashed, using a hash function optimized for ASCII and
+ * similar strings. It's weaker than the other hash functions.
+ *
+ * This hash may have different results on different machines, so is
+ * only useful for internal hashes (ie. not hashes sent across the
+ * network or saved to disk). The results will be different from the
+ * other hash functions in this module, too.
+ */
+static inline uint32_t hash_string(const char *string)
+{
+ /* This is Karl Nelson <kenelson@ece.ucdavis.edu>'s X31 hash.
+ * It's a little faster than the (much better) lookup3 hash(): 56ns vs
+ * 84ns on my 2GHz Intel Core Duo 2 laptop for a 10 char string. */
+ uint32_t ret;
+
+ for (ret = 0; *string; string++)
+ ret = (ret << 5) - ret + *string;
+
+ return ret;
+}
+
+/**
+ * hash64 - fast 64-bit hash of an array for internal use
+ * @p: the array or pointer to first element
+ * @num: the number of elements to hash
+ * @base: the 64-bit base number to roll into the hash (usually 0)
+ *
+ * The memory region pointed to by p is combined with the base to form
+ * a 64-bit hash.
+ *
+ * This hash will have different results on different machines, so is
+ * only useful for internal hashes (ie. not hashes sent across the
+ * network or saved to disk).
+ *
+ * It may also change with future versions: it could even detect at runtime
+ * what the fastest hash to use is.
+ *
+ * See also: hash.
+ *
+ * Example:
+ * #include <ccan/hash/hash.h>
+ * #include <err.h>
+ * #include <stdio.h>
+ *
+ * // Simple demonstration: idential strings will have the same hash, but
+ * // two different strings will probably not.
+ * int main(int argc, char *argv[])
+ * {
+ * uint64_t hash1, hash2;
+ *
+ * if (argc != 3)
+ * err(1, "Usage: %s <string1> <string2>", argv[0]);
+ *
+ * hash1 = hash64(argv[1], strlen(argv[1]), 0);
+ * hash2 = hash64(argv[2], strlen(argv[2]), 0);
+ * printf("Hash is %s\n", hash1 == hash2 ? "same" : "different");
+ * return 0;
+ * }
+ */
+#define hash64(p, num, base) hash64_any((p), (num)*sizeof(*(p)), (base))
+
+/**
+ * hash64_stable - 64 bit hash of an array for external use
+ * @p: the array or pointer to first element
+ * @num: the number of elements to hash
+ * @base: the base number to roll into the hash (usually 0)
+ *
+ * The array of simple integer types pointed to by p is combined with
+ * the base to form a 64-bit hash.
+ *
+ * This hash will have the same results on different machines, so can
+ * be used for external hashes (ie. hashes sent across the network or
+ * saved to disk). The results will not change in future versions of
+ * this module.
+ *
+ * Note that it is only legal to hand an array of simple integer types
+ * to this hash (ie. char, uint16_t, int64_t, etc). In these cases,
+ * the same values will have the same hash result, even though the
+ * memory representations of integers depend on the machine
+ * endianness.
+ *
+ * See also:
+ * hash_stable
+ *
+ * Example:
+ * #include <ccan/hash/hash.h>
+ * #include <err.h>
+ * #include <stdio.h>
+ *
+ * int main(int argc, char *argv[])
+ * {
+ * if (argc != 2)
+ * err(1, "Usage: %s <string-to-hash>", argv[0]);
+ *
+ * printf("Hash stable result is %llu\n",
+ * (long long)hash64_stable(argv[1], strlen(argv[1]), 0));
+ * return 0;
+ * }
+ */
+#define hash64_stable(p, num, base) \
+ (EXPR_BUILD_ASSERT(sizeof(*(p)) == 8 || sizeof(*(p)) == 4 \
+ || sizeof(*(p)) == 2 || sizeof(*(p)) == 1) + \
+ sizeof(*(p)) == 8 ? hash64_stable_64((p), (num), (base)) \
+ : sizeof(*(p)) == 4 ? hash64_stable_32((p), (num), (base)) \
+ : sizeof(*(p)) == 2 ? hash64_stable_16((p), (num), (base)) \
+ : hash64_stable_8((p), (num), (base)))
+
+
+/**
+ * hashl - fast 32/64-bit hash of an array for internal use
+ * @p: the array or pointer to first element
+ * @num: the number of elements to hash
+ * @base: the base number to roll into the hash (usually 0)
+ *
+ * This is either hash() or hash64(), on 32/64 bit long machines.
+ */
+#define hashl(p, num, base) \
+ (EXPR_BUILD_ASSERT(sizeof(long) == sizeof(uint32_t) \
+ || sizeof(long) == sizeof(uint64_t)) + \
+ (sizeof(long) == sizeof(uint64_t) \
+ ? hash64((p), (num), (base)) : hash((p), (num), (base))))
+
+/* Our underlying operations. */
+uint32_t hash_any(const void *key, size_t length, uint32_t base);
+uint32_t hash_stable_64(const void *key, size_t n, uint32_t base);
+uint32_t hash_stable_32(const void *key, size_t n, uint32_t base);
+uint32_t hash_stable_16(const void *key, size_t n, uint32_t base);
+uint32_t hash_stable_8(const void *key, size_t n, uint32_t base);
+uint64_t hash64_any(const void *key, size_t length, uint64_t base);
+uint64_t hash64_stable_64(const void *key, size_t n, uint64_t base);
+uint64_t hash64_stable_32(const void *key, size_t n, uint64_t base);
+uint64_t hash64_stable_16(const void *key, size_t n, uint64_t base);
+uint64_t hash64_stable_8(const void *key, size_t n, uint64_t base);
+
+/**
+ * hash_pointer - hash a pointer for internal use
+ * @p: the pointer value to hash
+ * @base: the base number to roll into the hash (usually 0)
+ *
+ * The pointer p (not what p points to!) is combined with the base to form
+ * a 32-bit hash.
+ *
+ * This hash will have different results on different machines, so is
+ * only useful for internal hashes (ie. not hashes sent across the
+ * network or saved to disk).
+ *
+ * Example:
+ * #include "hash/hash.h"
+ *
+ * // Code to keep track of memory regions.
+ * struct region {
+ * struct region *chain;
+ * void *start;
+ * unsigned int size;
+ * };
+ * // We keep a simple hash table.
+ * static struct region *region_hash[128];
+ *
+ * static void add_region(struct region *r)
+ * {
+ * unsigned int h = hash_pointer(r->start);
+ *
+ * r->chain = region_hash[h];
+ * region_hash[h] = r->chain;
+ * }
+ *
+ * static void find_region(const void *start)
+ * {
+ * struct region *r;
+ *
+ * for (r = region_hash[hash_pointer(start)]; r; r = r->chain)
+ * if (r->start == start)
+ * return r;
+ * return NULL;
+ * }
+ */
+static inline uint32_t hash_pointer(const void *p, uint32_t base)
+{
+ if (sizeof(p) % sizeof(uint32_t) == 0) {
+ /* This convoluted union is the right way of aliasing. */
+ union {
+ uint32_t u32[sizeof(p) / sizeof(uint32_t)];
+ const void *p;
+ } u;
+ u.p = p;
+ return hash_u32(u.u32, sizeof(p) / sizeof(uint32_t), base);
+ } else
+ return hash(&p, 1, base);
+}
+#endif /* HASH_H */
git.samba.org / metze / samba / wip.git / commitdiff