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1 /*-------------------------------------------------------------------------
2  * drawElements Base Portability Library
3  * -------------------------------------
4  *
5  * Copyright 2014 The Android Open Source Project
6  *
7  * Licensed under the Apache License, Version 2.0 (the "License");
8  * you may not use this file except in compliance with the License.
9  * You may obtain a copy of the License at
10  *
11  *      http://www.apache.org/licenses/LICENSE-2.0
12  *
13  * Unless required by applicable law or agreed to in writing, software
14  * distributed under the License is distributed on an "AS IS" BASIS,
15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16  * See the License for the specific language governing permissions and
17  * limitations under the License.
18  *
19  *//*!
20  * \file
21  * \brief Basic string operations.
22  *//*--------------------------------------------------------------------*/
23 
24 #include "deString.h"
25 
26 #include <string.h>
27 #include <stdlib.h>
28 
29 #include <stdio.h>
30 #include <stdarg.h>
31 
32 DE_BEGIN_EXTERN_C
33 
34 /*--------------------------------------------------------------------*//*!
35  * \brief Compute hash from string.
36  * \param str    String to compute hash value for.
37  * \return Computed hash value.
38  *//*--------------------------------------------------------------------*/
deStringHash(const char * str)39 uint32_t deStringHash(const char *str)
40 {
41     /* \note [pyry] This hash is used in DT_GNU_HASH and is proven
42     to be robust for symbol hashing. */
43     /* \see http://sources.redhat.com/ml/binutils/2006-06/msg00418.html */
44     uint32_t hash = 5381;
45     unsigned int c;
46 
47     DE_ASSERT(str);
48     while ((c = (unsigned int)*str++) != 0)
49         hash = (hash << 5) + hash + c;
50 
51     return hash;
52 }
53 
deStringHashLeading(const char * str,int numLeadingChars)54 uint32_t deStringHashLeading(const char *str, int numLeadingChars)
55 {
56     uint32_t hash = 5381;
57     unsigned int c;
58 
59     DE_ASSERT(str);
60     while (numLeadingChars-- && (c = (unsigned int)*str++) != 0)
61         hash = (hash << 5) + hash + c;
62 
63     return hash;
64 }
65 
deMemoryHash(const void * ptr,size_t numBytes)66 uint32_t deMemoryHash(const void *ptr, size_t numBytes)
67 {
68     /* \todo [2010-05-10 pyry] Better generic hash function? */
69     const uint8_t *input = (const uint8_t *)ptr;
70     uint32_t hash        = 5381;
71 
72     DE_ASSERT(ptr);
73     while (numBytes--)
74         hash = (hash << 5) + hash + *input++;
75 
76     return hash;
77 }
78 
deStringBeginsWith(const char * str,const char * lead)79 bool deStringBeginsWith(const char *str, const char *lead)
80 {
81     const char *a = str;
82     const char *b = lead;
83 
84     while (*b)
85     {
86         if (*a++ != *b++)
87             return false;
88     }
89 
90     return true;
91 }
92 
93 DE_END_EXTERN_C
94