X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=hashtable%2Fhash.c;fp=hashtable%2Fhash.c;h=0000000000000000000000000000000000000000;hp=12f76d834e0a12ba7269d0f80227b4f3985f093b;hb=daf282ab93462198c6acd16b4aa624635df1bea5;hpb=10d32e930a6b67c3f196ca3bf4f247d444d8c2b6 diff --git a/hashtable/hash.c b/hashtable/hash.c deleted file mode 100644 index 12f76d834..000000000 --- a/hashtable/hash.c +++ /dev/null @@ -1,504 +0,0 @@ -/* - * Copyright (C) - Bob Jenkins, May 2006, Public Domain. - * Copyright (C) 2011 - David Goulet - * Copyright (C) 2011 - Mathieu Desnoyers - * - * 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 /* defines printf for tests */ -#include /* defines time_t for timings in the test */ -#include /* defines uint32_t etc */ -#include /* attempt to define endianness */ -#include /* attempt to define endianness */ -#include -#include -#include - -/* - * 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 -# 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); \ -} - -static __attribute__((unused)) -uint32_t hashword( - 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; -} - - -/* - * hashword2() -- same as hashword(), 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(). - */ -static __attribute__((unused)) -void hashword2(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; - - while (length > 3) { - a += k[0]; - b += k[1]; - c += k[2]; - mix(a, b, c); - length -= 3; - k += 3; - } - - switch (length) { - 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; - } - - *pc = c; - *pb = b; -} - -/* - * 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) { - a += k[0]; - b += k[1]; - c += k[2]; - mix(a,b,c); - length -= 12; - k += 3; - } - - /* - * "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 */ - const uint8_t *k8; - - 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; - } - - 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; - - 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; - } - - 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; -} - -#if (CAA_BITS_PER_LONG == 64) -/* - * Hash function for number value. - */ -unsigned long hash_key(void *_key, size_t length, unsigned long seed) -{ - union { - uint64_t v64; - uint32_t v32[2]; - } v; - union { - uint64_t v64; - uint32_t v32[2]; - } key; - - assert(length == sizeof(unsigned long)); - v.v64 = (uint64_t) seed; - key.v64 = (uint64_t) _key; - hashword2(key.v32, 2, &v.v32[0], &v.v32[1]); - return v.v64; -} -#else -/* - * Hash function for number value. - */ -unsigned long hash_key(void *_key, size_t length, unsigned long seed) -{ - uint32_t key = (uint32_t) _key; - - assert(length == sizeof(uint32_t)); - return hashword(&key, 1, seed); -} -#endif - -/* - * Hash function for string. - */ -unsigned long hash_key_str(void *key, size_t length, unsigned long seed) -{ - return hashlittle(key, length, seed); -} - -/* - * Hash function compare for number value. - */ -unsigned long hash_compare_key(void *key1, size_t key1_len, - void *key2, size_t key2_len) -{ - if (key1_len != key2_len) { - return -1; - } - - if (key1 == key2) { - return 0; - } - - return 1; -} - -/* - * Hash compare function for string. - */ -unsigned long hash_compare_key_str(void *key1, size_t key1_len, - void *key2, size_t key2_len) -{ - if (key1_len != key2_len) { - return -1; - } - - if (strncmp(key1, key2, key1_len) == 0) { - return 0; - } - - return 1; -}