#endif
} ovs_32aligned_u64;
+typedef union {
+ uint32_t u32[4];
+ struct {
+ uint64_t lo, hi;
+ } u64;
+} ovs_u128;
+
+/* Returns non-zero if the parameters have equal value. */
+static inline int
+ovs_u128_equal(const ovs_u128 *a, const ovs_u128 *b)
+{
+ return (a->u64.hi == b->u64.hi) && (a->u64.lo == b->u64.lo);
+}
+
/* A 64-bit value, in network byte order, that is only aligned on a 32-bit
* boundary. */
typedef struct {
/*
- * Copyright (c) 2008, 2009, 2010, 2012, 2013 Nicira, Inc.
+ * Copyright (c) 2008, 2009, 2010, 2012, 2013, 2014 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
{
return hash_words64_inline(p, n_words, basis);
}
+
+#if !(defined(__x86_64__))
+void
+hash_bytes128(const void *p_, size_t len, uint32_t basis, ovs_u128 *out)
+{
+ const uint32_t c1 = 0x239b961b;
+ const uint32_t c2 = 0xab0e9789;
+ const uint32_t c3 = 0x38b34ae5;
+ const uint32_t c4 = 0xa1e38b93;
+ const uint8_t *tail, *data = (const uint8_t *)p_;
+ const uint32_t *blocks = (const uint32_t *)p_;
+ const int nblocks = len / 16;
+ uint32_t h1 = basis;
+ uint32_t h2 = basis;
+ uint32_t h3 = basis;
+ uint32_t h4 = basis;
+ uint32_t k1, k2, k3, k4;
+
+ /* Body */
+ for (int i = 0; i < nblocks; i++) {
+ uint32_t k1 = get_unaligned_u32(&blocks[i * 4 + 0]);
+ uint32_t k2 = get_unaligned_u32(&blocks[i * 4 + 1]);
+ uint32_t k3 = get_unaligned_u32(&blocks[i * 4 + 2]);
+ uint32_t k4 = get_unaligned_u32(&blocks[i * 4 + 3]);
+
+ k1 *= c1;
+ k1 = hash_rot(k1, 15);
+ k1 *= c2;
+ h1 ^= k1;
+
+ h1 = hash_rot(h1, 19);
+ h1 += h2;
+ h1 = h1 * 5 + 0x561ccd1b;
+
+ k2 *= c2;
+ k2 = hash_rot(k2, 16);
+ k2 *= c3;
+ h2 ^= k2;
+
+ h2 = hash_rot(h2, 17);
+ h2 += h3;
+ h2 = h2 * 5 + 0x0bcaa747;
+
+ k3 *= c3;
+ k3 = hash_rot(k3, 17);
+ k3 *= c4;
+ h3 ^= k3;
+
+ h3 = hash_rot(h3, 15);
+ h3 += h4;
+ h3 = h3 * 5 + 0x96cd1c35;
+
+ k4 *= c4;
+ k4 = hash_rot(k4, 18);
+ k4 *= c1;
+ h4 ^= k4;
+
+ h4 = hash_rot(h4, 13);
+ h4 += h1;
+ h4 = h4 * 5 + 0x32ac3b17;
+ }
+
+ /* Tail */
+ k1 = k2 = k3 = k4 = 0;
+ tail = data + nblocks * 16;
+ switch (len & 15) {
+ case 15:
+ k4 ^= tail[14] << 16;
+ case 14:
+ k4 ^= tail[13] << 8;
+ case 13:
+ k4 ^= tail[12] << 0;
+ k4 *= c4;
+ k4 = hash_rot(k4, 18);
+ k4 *= c1;
+ h4 ^= k4;
+
+ case 12:
+ k3 ^= tail[11] << 24;
+ case 11:
+ k3 ^= tail[10] << 16;
+ case 10:
+ k3 ^= tail[9] << 8;
+ case 9:
+ k3 ^= tail[8] << 0;
+ k3 *= c3;
+ k3 = hash_rot(k3, 17);
+ k3 *= c4;
+ h3 ^= k3;
+
+ case 8:
+ k2 ^= tail[7] << 24;
+ case 7:
+ k2 ^= tail[6] << 16;
+ case 6:
+ k2 ^= tail[5] << 8;
+ case 5:
+ k2 ^= tail[4] << 0;
+ k2 *= c2;
+ k2 = hash_rot(k2, 16);
+ k2 *= c3;
+ h2 ^= k2;
+
+ case 4:
+ k1 ^= tail[3] << 24;
+ case 3:
+ k1 ^= tail[2] << 16;
+ case 2:
+ k1 ^= tail[1] << 8;
+ case 1:
+ k1 ^= tail[0] << 0;
+ k1 *= c1;
+ k1 = hash_rot(k1, 15);
+ k1 *= c2;
+ h1 ^= k1;
+ };
+
+ /* Finalization */
+ h1 ^= len;
+ h2 ^= len;
+ h3 ^= len;
+ h4 ^= len;
+
+ h1 += h2;
+ h1 += h3;
+ h1 += h4;
+ h2 += h1;
+ h3 += h1;
+ h4 += h1;
+
+ h1 = mhash_finish(h1);
+ h2 = mhash_finish(h2);
+ h3 = mhash_finish(h3);
+ h4 = mhash_finish(h4);
+
+ h1 += h2;
+ h1 += h3;
+ h1 += h4;
+ h2 += h1;
+ h3 += h1;
+ h4 += h1;
+
+ out->u32[0] = h1;
+ out->u32[1] = h2;
+ out->u32[2] = h3;
+ out->u32[3] = h4;
+}
+
+#else /* __x86_64__ */
+
+static inline uint64_t
+hash_rot64(uint64_t x, int8_t r)
+{
+ return (x << r) | (x >> (64 - r));
+}
+
+static inline uint64_t
+fmix64(uint64_t k)
+{
+ k ^= k >> 33;
+ k *= 0xff51afd7ed558ccdULL;
+ k ^= k >> 33;
+ k *= 0xc4ceb9fe1a85ec53ULL;
+ k ^= k >> 33;
+
+ return k;
+}
+
+void
+hash_bytes128(const void *p_, size_t len, uint32_t basis, ovs_u128 *out)
+{
+ const uint64_t c1 = 0x87c37b91114253d5ULL;
+ const uint64_t c2 = 0x4cf5ad432745937fULL;
+ const uint8_t *tail, *data = (const uint8_t *)p_;
+ const uint64_t *blocks = (const uint64_t *)p_;
+ const int nblocks = len / 16;
+ uint64_t h1 = basis;
+ uint64_t h2 = basis;
+ uint64_t k1, k2;
+
+ /* Body */
+ for (int i = 0; i < nblocks; i++) {
+ k1 = get_unaligned_u64(&blocks[i * 2 + 0]);
+ k2 = get_unaligned_u64(&blocks[i * 2 + 1]);
+
+ k1 *= c1;
+ k1 = hash_rot64(k1, 31);
+ k1 *= c2;
+ h1 ^= k1;
+
+ h1 = hash_rot64(h1, 27);
+ h1 += h2;
+ h1 = h1 * 5 + 0x52dce729;
+
+ k2 *= c2;
+ k2 = hash_rot64(k2, 33);
+ k2 *= c1;
+ h2 ^= k2;
+
+ h2 = hash_rot64(h2, 31);
+ h2 += h1;
+ h2 = h2 * 5 + 0x38495ab5;
+ }
+
+ /* Tail */
+ k1 = 0;
+ k2 = 0;
+ tail = data + nblocks * 16;
+ switch (len & 15) {
+ case 15:
+ k2 ^= ((uint64_t) tail[14]) << 48;
+ case 14:
+ k2 ^= ((uint64_t) tail[13]) << 40;
+ case 13:
+ k2 ^= ((uint64_t) tail[12]) << 32;
+ case 12:
+ k2 ^= ((uint64_t) tail[11]) << 24;
+ case 11:
+ k2 ^= ((uint64_t) tail[10]) << 16;
+ case 10:
+ k2 ^= ((uint64_t) tail[9]) << 8;
+ case 9:
+ k2 ^= ((uint64_t) tail[8]) << 0;
+ k2 *= c2;
+ k2 = hash_rot64(k2, 33);
+ k2 *= c1;
+ h2 ^= k2;
+
+ case 8:
+ k1 ^= ((uint64_t) tail[7]) << 56;
+ case 7:
+ k1 ^= ((uint64_t) tail[6]) << 48;
+ case 6:
+ k1 ^= ((uint64_t) tail[5]) << 40;
+ case 5:
+ k1 ^= ((uint64_t) tail[4]) << 32;
+ case 4:
+ k1 ^= ((uint64_t) tail[3]) << 24;
+ case 3:
+ k1 ^= ((uint64_t) tail[2]) << 16;
+ case 2:
+ k1 ^= ((uint64_t) tail[1]) << 8;
+ case 1:
+ k1 ^= ((uint64_t) tail[0]) << 0;
+ k1 *= c1;
+ k1 = hash_rot64(k1, 31);
+ k1 *= c2;
+ h1 ^= k1;
+ };
+
+ /* Finalization */
+ h1 ^= len;
+ h2 ^= len;
+ h1 += h2;
+ h2 += h1;
+ h1 = fmix64(h1);
+ h2 = fmix64(h2);
+ h1 += h2;
+ h2 += h1;
+
+ out->u64.lo = h1;
+ out->u64.hi = h2;
+}
+#endif /* __x86_64__ */
/*
- * Copyright (c) 2008, 2009, 2010, 2012, 2013 Nicira, Inc.
+ * Copyright (c) 2008, 2009, 2010, 2012, 2013, 2014 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
}
uint32_t hash_bytes(const void *, size_t n_bytes, uint32_t basis);
+void hash_bytes128(const void *_, size_t n_bytes, uint32_t basis,
+ ovs_u128 *out);
static inline uint32_t hash_int(uint32_t x, uint32_t basis);
static inline uint32_t hash_2words(uint32_t, uint32_t);
return hash * 5 + 0xe6546b64;
}
-static inline uint32_t mhash_finish(uint32_t hash, uint32_t n_bytes)
+static inline uint32_t mhash_finish(uint32_t hash)
{
- hash ^= n_bytes;
hash ^= hash >> 16;
hash *= 0x85ebca6b;
hash ^= hash >> 13;
}
#if !(defined(__SSE4_2__) && defined(__x86_64__))
-/* Mhash-based implemantation. */
+/* Mhash-based implementation. */
static inline uint32_t hash_add(uint32_t hash, uint32_t data)
{
static inline uint32_t hash_finish(uint32_t hash, uint32_t final)
{
- return mhash_finish(hash, final);
+ return mhash_finish(hash ^ final);
}
/* Returns the hash of the 'n' 32-bit words at 'p', starting from 'basis'.
}
}
+static void
+set_bit128(ovs_u128 array[16], int bit)
+{
+ assert(bit >= 0 && bit <= 2048);
+ memset(array, 0, sizeof(ovs_u128) * 16);
+ if (bit < 2048) {
+ int b = bit % 128;
+
+ if (b < 64) {
+ array[bit / 128].u64.lo = UINT64_C(1) << (b % 64);
+ } else {
+ array[bit / 128].u64.hi = UINT64_C(1) << (b % 64);
+ }
+ }
+}
+
static uint32_t
hash_words_cb(uint32_t input)
{
return hash_int(input, 0);
}
+static uint32_t
+hash_bytes128_cb(uint32_t input)
+{
+ ovs_u128 hash;
+
+ hash_bytes128(&input, sizeof input, 0, &hash);
+ return hash.u64.lo;
+}
+
static void
check_word_hash(uint32_t (*hash)(uint32_t), const char *name,
int min_unique)
}
}
+static void
+check_256byte_hash(void (*hash)(const void *, size_t, uint32_t, ovs_u128 *),
+ const char *name, const int min_unique)
+{
+ const uint64_t unique_mask = (UINT64_C(1) << min_unique) - 1;
+ const int n_bits = 256 * 8;
+ int i, j;
+
+ for (i = 0; i < n_bits; i++) {
+ for (j = i + 1; j < n_bits; j++) {
+ OVS_PACKED(struct offset_ovs_u128 {
+ uint32_t a;
+ ovs_u128 b[16];
+ }) in0_data;
+ ovs_u128 *in0, in1[16], in2[16];
+ ovs_u128 out0, out1, out2;
+
+ in0 = in0_data.b;
+ set_bit128(in0, i);
+ set_bit128(in1, i);
+ set_bit128(in2, j);
+ hash(in0, sizeof(ovs_u128) * 16, 0, &out0);
+ hash(in1, sizeof(ovs_u128) * 16, 0, &out1);
+ hash(in2, sizeof(ovs_u128) * 16, 0, &out2);
+ if (!ovs_u128_equal(&out0, &out1)) {
+ printf("%s hash not the same for non-64 aligned data "
+ "%016"PRIx64"%016"PRIx64" != %016"PRIx64"%016"PRIx64"\n",
+ name, out0.u64.lo, out0.u64.hi, out1.u64.lo, out1.u64.hi);
+ }
+ if ((out1.u64.lo & unique_mask) == (out2.u64.lo & unique_mask)) {
+ printf("%s has a partial collision:\n", name);
+ printf("hash(1 << %4d) == %016"PRIx64"%016"PRIx64"\n", i,
+ out1.u64.hi, out1.u64.lo);
+ printf("hash(1 << %4d) == %016"PRIx64"%016"PRIx64"\n", j,
+ out2.u64.hi, out2.u64.lo);
+ printf("The low-order %d bits of output are both "
+ "0x%"PRIx64"\n", min_unique, out1.u64.lo & unique_mask);
+ }
+ }
+ }
+}
+
static void
test_hash_main(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
{
* function.
*/
check_word_hash(hash_int_cb, "hash_int", 12);
+ check_word_hash(hash_bytes128_cb, "hash_bytes128", 12);
+
+ /* Check that all hashes computed with hash_bytes128 with 1-bit (or no
+ * 1-bits) set within 16 128-bit words have different values in their
+ * lowest 23 bits.
+ *
+ * Given a random distribution, the probability of at least one collision
+ * in any set of 23 bits is approximately
+ *
+ * 1 - ((2**23 - 1)/2**23)**C(2049,2)
+ * == 1 - (8,388,607/8,388,608)**2,098,176
+ * =~ 0.22
+ *
+ * so we are doing pretty well to not have any collisions in 23 bits.
+ */
+ check_256byte_hash(hash_bytes128, "hash_bytes128", 23);
}
OVSTEST_REGISTER("test-hash", test_hash_main);