X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Fjhash.h;fp=liblttng-ust%2Fjhash.h;h=0000000000000000000000000000000000000000;hb=9d4c8b2d907edb9ebc9bfde55602598e7ba0832e;hp=bd34cc5940d4a5a3b00b439ee653a82f87dd01a4;hpb=6ba6fd60507f8e045bdc4f1be14e9d99c6a15f7f;p=lttng-ust.git diff --git a/liblttng-ust/jhash.h b/liblttng-ust/jhash.h deleted file mode 100644 index bd34cc59..00000000 --- a/liblttng-ust/jhash.h +++ /dev/null @@ -1,224 +0,0 @@ -/* - * SPDX-License-Identifier: LGPL-2.1-only - * - * Copyright (C) 2011 Mathieu Desnoyers - */ - -#include -#include -#include -#include - -/* - * Hash function - * Source: http://burtleburtle.net/bob/c/lookup3.c - * Originally Public Domain - */ - -#define rot(x, k) (((x) << (k)) | ((x) >> (32 - (k)))) - -#define mix(a, b, c) \ -do { \ - 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; \ -} while (0) - -#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); \ -} - -#if (BYTE_ORDER == LITTLE_ENDIAN) -#define HASH_LITTLE_ENDIAN 1 -#else -#define HASH_LITTLE_ENDIAN 0 -#endif - -/* - * - * 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 < 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 initval) -{ - uint32_t a, b, c; /* internal state */ - union { - const void *ptr; - size_t i; - } u; - - /* Set up the internal state */ - a = b = c = 0xdeadbeef + ((uint32_t)length) + initval; - - u.ptr = key; - if (HASH_LITTLE_ENDIAN && ((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 */ - /* - * The original jhash.h reads beyond the end of string, and implements - * a special code path for VALGRIND. It seems to make ASan unhappy too - * though, so considering that hashing event names is not a fast-path - * in lttng-ust, remove the "fast" code entirely and use the slower - * but verifiable VALGRIND version of the code which does not issue - * out-of-bound reads. - */ - { - 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; - } - } - - } 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; /* fall through */ - case 11: c+=((uint32_t) k[10])<<16; /* fall through */ - case 10: c+=((uint32_t) k[9])<<8; /* fall through */ - case 9 : c+=k[8]; /* fall through */ - case 8 : b+=((uint32_t) k[7])<<24; /* fall through */ - case 7 : b+=((uint32_t) k[6])<<16; /* fall through */ - case 6 : b+=((uint32_t) k[5])<<8; /* fall through */ - case 5 : b+=k[4]; /* fall through */ - case 4 : a+=((uint32_t) k[3])<<24; /* fall through */ - case 3 : a+=((uint32_t) k[2])<<16; /* fall through */ - case 2 : a+=((uint32_t) k[1])<<8; /* fall through */ - case 1 : a+=k[0]; - break; - case 0 : return c; - } - } - - final(a, b, c); - return c; -} - -static inline -uint32_t jhash(const void *key, size_t length, uint32_t seed) -{ - return hashlittle(key, length, seed); -}