1+ namespace GameFrameX . Foundation . Hash ;
2+
3+ /// <summary>
4+ /// CRC校验相关的实用函数。
5+ /// 提供CRC32和CRC64两种校验算法的实现。
6+ /// </summary>
7+ public static partial class CrcHelper
8+ {
9+ /// <summary>
10+ /// 缓存字节数组的长度,用于分块读取大文件
11+ /// </summary>
12+ private const int CachedBytesLength = 0x1000 ;
13+
14+ /// <summary>
15+ /// 用于缓存读取数据的字节数组
16+ /// </summary>
17+ private static readonly byte [ ] SCachedBytes = new byte [ CachedBytesLength ] ;
18+
19+ /// <summary>
20+ /// CRC32算法的实例
21+ /// </summary>
22+ private static readonly CrcHelper . Crc32 SAlgorithm = new ( ) ;
23+
24+ /// <summary>
25+ /// CRC64算法的实例
26+ /// </summary>
27+ private static readonly CrcHelper . Crc64 SAlgorithm64 = new ( ) ;
28+
29+ /// <summary>
30+ /// 计算二进制流的CRC64值
31+ /// </summary>
32+ /// <param name="bytes">要计算的二进制字节数组</param>
33+ /// <returns>计算得到的CRC64校验值</returns>
34+ public static ulong GetCrc64 ( byte [ ] bytes )
35+ {
36+ SAlgorithm64 . Reset ( ) ;
37+ SAlgorithm64 . Append ( bytes ) ;
38+ return SAlgorithm64 . GetCurrentHashAsUInt64 ( ) ;
39+ }
40+
41+ /// <summary>
42+ /// 计算流的CRC64值
43+ /// </summary>
44+ /// <param name="stream">要计算的数据流</param>
45+ /// <returns>计算得到的CRC64校验值</returns>
46+ public static ulong GetCrc64 ( Stream stream )
47+ {
48+ SAlgorithm64 . Reset ( ) ;
49+ SAlgorithm64 . Append ( stream ) ;
50+ return SAlgorithm64 . GetCurrentHashAsUInt64 ( ) ;
51+ }
52+
53+ /// <summary>
54+ /// 计算二进制流的CRC32值
55+ /// </summary>
56+ /// <param name="bytes">要计算的二进制字节数组</param>
57+ /// <returns>计算得到的CRC32校验值</returns>
58+ /// <exception cref="ArgumentNullException">当bytes参数为null时抛出</exception>
59+ public static int GetCrc32 ( byte [ ] bytes )
60+ {
61+ if ( bytes == null )
62+ {
63+ throw new ArgumentNullException ( nameof ( bytes ) , "Bytes is invalid." ) ;
64+ }
65+
66+ return GetCrc32 ( bytes , 0 , bytes . Length ) ;
67+ }
68+
69+ /// <summary>
70+ /// 计算二进制流指定范围的CRC32值
71+ /// </summary>
72+ /// <param name="bytes">要计算的二进制字节数组</param>
73+ /// <param name="offset">起始偏移量</param>
74+ /// <param name="length">要计算的长度</param>
75+ /// <returns>计算得到的CRC32校验值</returns>
76+ /// <exception cref="ArgumentNullException">当bytes参数为null时抛出</exception>
77+ /// <exception cref="ArgumentException">当offset或length参数无效时抛出</exception>
78+ public static int GetCrc32 ( byte [ ] bytes , int offset , int length )
79+ {
80+ if ( bytes == null )
81+ {
82+ throw new ArgumentNullException ( nameof ( bytes ) , "Bytes is invalid." ) ;
83+ }
84+
85+ if ( offset < 0 || length < 0 || offset + length > bytes . Length )
86+ {
87+ throw new ArgumentException ( "Offset or length is invalid." , nameof ( offset ) ) ;
88+ }
89+
90+ SAlgorithm . HashCore ( bytes , offset , length ) ;
91+ var result = ( int ) SAlgorithm . HashFinal ( ) ;
92+ SAlgorithm . Initialize ( ) ;
93+ return result ;
94+ }
95+
96+ /// <summary>
97+ /// 计算流的CRC32值
98+ /// </summary>
99+ /// <param name="stream">要计算的数据流</param>
100+ /// <returns>计算得到的CRC32校验值</returns>
101+ /// <exception cref="ArgumentNullException">当stream参数为null时抛出</exception>
102+ public static int GetCrc32 ( Stream stream )
103+ {
104+ if ( stream == null )
105+ {
106+ throw new ArgumentNullException ( nameof ( stream ) , "Stream is invalid." ) ;
107+ }
108+
109+ while ( true )
110+ {
111+ var bytesRead = stream . Read ( SCachedBytes , 0 , CachedBytesLength ) ;
112+ if ( bytesRead > 0 )
113+ {
114+ SAlgorithm . HashCore ( SCachedBytes , 0 , bytesRead ) ;
115+ }
116+ else
117+ {
118+ break ;
119+ }
120+ }
121+
122+ var result = ( int ) SAlgorithm . HashFinal ( ) ;
123+ SAlgorithm . Initialize ( ) ;
124+ Array . Clear ( SCachedBytes , 0 , CachedBytesLength ) ;
125+ return result ;
126+ }
127+
128+ /// <summary>
129+ /// 将CRC32值转换为字节数组
130+ /// </summary>
131+ /// <param name="crc32">要转换的CRC32值</param>
132+ /// <returns>转换后的4字节数组，按大端序排列</returns>
133+ public static byte [ ] GetCrc32Bytes ( int crc32 )
134+ {
135+ return new [ ] { ( byte ) ( ( crc32 >> 24 ) & 0xff ) , ( byte ) ( ( crc32 >> 16 ) & 0xff ) , ( byte ) ( ( crc32 >> 8 ) & 0xff ) , ( byte ) ( crc32 & 0xff ) , } ;
136+ }
137+
138+ /// <summary>
139+ /// 将CRC32值转换为字节数组并存入指定数组
140+ /// </summary>
141+ /// <param name="crc32">要转换的CRC32值</param>
142+ /// <param name="bytes">存放结果的目标数组</param>
143+ public static void GetCrc32Bytes ( int crc32 , byte [ ] bytes )
144+ {
145+ GetCrc32Bytes ( crc32 , bytes , 0 ) ;
146+ }
147+
148+ /// <summary>
149+ /// 将CRC32值转换为字节数组并存入指定数组的指定位置
150+ /// </summary>
151+ /// <param name="crc32">要转换的CRC32值</param>
152+ /// <param name="bytes">存放结果的目标数组</param>
153+ /// <param name="offset">在目标数组中的起始位置</param>
154+ /// <exception cref="ArgumentNullException">当bytes参数为null时抛出</exception>
155+ /// <exception cref="ArgumentException">当offset参数无效或目标数组剩余空间不足4字节时抛出</exception>
156+ public static void GetCrc32Bytes ( int crc32 , byte [ ] bytes , int offset )
157+ {
158+ if ( bytes == null )
159+ {
160+ throw new ArgumentNullException ( nameof ( bytes ) , "Result is invalid." ) ;
161+ }
162+
163+ if ( offset < 0 || offset + 4 > bytes . Length )
164+ {
165+ throw new ArgumentException ( "Offset or length is invalid." , nameof ( offset ) ) ;
166+ }
167+
168+ bytes [ offset ] = ( byte ) ( ( crc32 >> 24 ) & 0xff ) ;
169+ bytes [ offset + 1 ] = ( byte ) ( ( crc32 >> 16 ) & 0xff ) ;
170+ bytes [ offset + 2 ] = ( byte ) ( ( crc32 >> 8 ) & 0xff ) ;
171+ bytes [ offset + 3 ] = ( byte ) ( crc32 & 0xff ) ;
172+ }
173+
174+ /// <summary>
175+ /// 使用指定编码计算流的CRC32值
176+ /// </summary>
177+ /// <param name="stream">要计算的数据流</param>
178+ /// <param name="code">用于编码的字节数组，将与数据进行XOR运算</param>
179+ /// <param name="length">要计算的字节数，如果为负数或超过流长度则使用整个流</param>
180+ /// <returns>计算得到的CRC32校验值</returns>
181+ /// <exception cref="ArgumentNullException">当stream或code参数为null时抛出</exception>
182+ /// <exception cref="ArgumentException">当code长度小于等于0时抛出</exception>
183+ internal static int GetCrc32 ( Stream stream , byte [ ] code , int length )
184+ {
185+ if ( stream == null )
186+ {
187+ throw new ArgumentNullException ( nameof ( stream ) , "Stream is invalid." ) ;
188+ }
189+
190+ if ( code == null )
191+ {
192+ throw new ArgumentNullException ( nameof ( code ) , "Code is invalid." ) ;
193+ }
194+
195+ var codeLength = code . Length ;
196+ if ( codeLength <= 0 )
197+ {
198+ throw new ArgumentException ( "Code length is invalid." , nameof ( codeLength ) ) ;
199+ }
200+
201+ var bytesLength = ( int ) stream . Length ;
202+ if ( length < 0 || length > bytesLength )
203+ {
204+ length = bytesLength ;
205+ }
206+
207+ var codeIndex = 0 ;
208+ while ( true )
209+ {
210+ var bytesRead = stream . Read ( SCachedBytes , 0 , CachedBytesLength ) ;
211+ if ( bytesRead > 0 )
212+ {
213+ if ( length > 0 )
214+ {
215+ for ( var i = 0 ; i < bytesRead && i < length ; i ++ )
216+ {
217+ SCachedBytes [ i ] ^= code [ codeIndex ++ ] ;
218+ codeIndex %= codeLength ;
219+ }
220+
221+ length -= bytesRead ;
222+ }
223+
224+ SAlgorithm . HashCore ( SCachedBytes , 0 , bytesRead ) ;
225+ }
226+ else
227+ {
228+ break ;
229+ }
230+ }
231+
232+ var result = ( int ) SAlgorithm . HashFinal ( ) ;
233+ SAlgorithm . Initialize ( ) ;
234+ Array . Clear ( SCachedBytes , 0 , CachedBytesLength ) ;
235+ return result ;
236+ }
237+ }
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