1/*
2 * Copyright (C) 2013 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "SixCharacterHash.h"
28
29#include <wtf/StdLibExtras.h>
30
31#include <string.h>
32
33namespace WTF {
34
35#define TABLE ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789")
36
37unsigned sixCharacterHashStringToInteger(const char* string)
38{
39    unsigned hash = 0;
40
41    RELEASE_ASSERT(strlen(string) == 6);
42
43    for (unsigned i = 0; i < 6; ++i) {
44        hash *= 62;
45        unsigned c = string[i];
46        if (c >= 'A' && c <= 'Z') {
47            hash += c - 'A';
48            continue;
49        }
50        if (c >= 'a' && c <= 'z') {
51            hash += c - 'a' + 26;
52            continue;
53        }
54        ASSERT(c >= '0' && c <= '9');
55        hash += c - '0' + 26 * 2;
56    }
57
58    return hash;
59}
60
61std::array<char, 7> integerToSixCharacterHashString(unsigned hash)
62{
63    static_assert(WTF_ARRAY_LENGTH(TABLE) - 1 == 62, "Six character hash table is not 62 characters long.");
64
65    std::array<char, 7> buffer;
66    unsigned accumulator = hash;
67    for (unsigned i = 6; i--;) {
68        buffer[i] = TABLE[accumulator % 62];
69        accumulator /= 62;
70    }
71    buffer[6] = 0;
72    return buffer;
73}
74
75} // namespace WTF
76
77