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git.proxmox.com Git - mirror_ovs.git/blob - lib/hash.c
2 * Copyright (c) 2008, 2009, 2010, 2012, 2013 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
19 #include "unaligned.h"
21 /* Returns the hash of 'a', 'b', and 'c'. */
23 hash_3words(uint32_t a
, uint32_t b
, uint32_t c
)
25 return mhash_finish(mhash_add(mhash_add(mhash_add(a
, 0), b
), c
), 12);
28 /* Returns the hash of the 'n' bytes at 'p', starting from 'basis'. */
30 hash_bytes(const void *p_
, size_t n
, uint32_t basis
)
32 const uint32_t *p
= p_
;
38 hash
= mhash_add(hash
, get_unaligned_u32(p
));
47 hash
= mhash_add__(hash
, tmp
);
50 return mhash_finish(hash
, orig_n
);
53 /* Returns the hash of the 'n' 32-bit words at 'p', starting from 'basis'.
54 * 'p' must be properly aligned. */
56 hash_words(const uint32_t p
[], size_t n_words
, uint32_t basis
)
62 for (i
= 0; i
< n_words
; i
++) {
63 hash
= mhash_add(hash
, p
[i
]);
65 return mhash_finish(hash
, n_words
* 4);
69 hash_double(double x
, uint32_t basis
)
72 BUILD_ASSERT_DECL(sizeof x
== sizeof value
);
74 memcpy(value
, &x
, sizeof value
);
75 return hash_3words(value
[0], value
[1], basis
);