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