【搬运】VB.NET和C#的CRC32校验，适合大型计算
C#代码
//
C#源代码
namespace
CLSO
{
class
CRC
{
public
static
readonly
uint
[] Table;
static
CRC()
{
Table
=
new
uint
[
256
];
const
uint
kPoly
=
0xEDB88320
;
for
(
uint
i
=
0
; i
<
256
; i
++
)
{
uint
r
=
i;
for
(
int
j
=
0
; j
<
8
; j
++
)
if
((r
&
1
)
!=
0
)
r
=
(r
>>
1
)
^
kPoly;
else
r
>>=
1
;
Table[i]
=
r;
}
}
uint
_value
=
0xFFFFFFFF
;
public
void
Init() { _value
=
0xFFFFFFFF
; }
public
void
UpdateByte(
byte
b)
{
_value
=
Table[(((
byte
)(_value))
^
b)]
^
(_value
>>
8
);
}
public
void
Update(
byte
[] data,
uint
offset,
uint
size)
{
for
(
uint
i
=
0
; i
<
size; i
++
)
_value
=
Table[((
byte
)_value)
^
data[offset
+
i]]
^
(_value
>>
8
);
}
public
uint
GetDigest() {
return
_value
^
0xFFFFFFFF
; }
static
uint
CalculateDigest(
byte
[] data,
uint
offset,
uint
size)
{
CRC crc
=
new
CRC();
//
crc.Init();
crc.Update(data, offset, size);
return
crc.GetDigest();
}
static
bool
VerifyDigest(
uint
digest,
byte
[] data,
uint
offset,
uint
size)
{
return
(CalculateDigest(data, offset, size)
==
digest);
}
}
}
VB代码
'
VB源代码
'
注意：本代码仅运行于VB 2005，不适用VB 2003
Public
Class
ClsoCRC
Public
Shared
ReadOnly
Table
As
UInteger
()
Shared
Sub
New
()
ReDim
Table(
256
)
For
i
As
UInteger
=
0
To
255
Dim
r
As
UInteger
=
i
For
j
As
Integer
=
0
To
7
If
(r
And
1
)
<>
0
Then
r
=
(r
>>
1
)
Xor
3988292384
Else
r
>>=
1
End
If
Next
Table(i)
=
r
Next
End Sub
Private
_value
As
UInteger
=
UInteger
.MaxValue
'''
<summary>
初始化类，重新计算CRC前请先调用本过程。
</summary>
Public
Sub
Init()
_value
=
UInt32.MaxValue
End Sub
'''
<summary>
更新并计算单个字节。(追加方式)
</summary>
'''
<param name="b">
数据字节。
</param>
Public
Sub
UpdateByte(
ByVal
b
As
Byte
)
_value
=
Table(UInt32toByte(_value)
Xor
b)
Xor
(_value
>>
8
)
End Sub
'''
<summary>
更新类并开始计算CRC。
</summary>
'''
<param name="data">
需要计算的数据组。
</param>
'''
<param name="offset">
偏移，一般设为0。
</param>
'''
<param name="size">
大小，一般设为数据组的Length。
</param>
Public
Sub
Update(
ByVal
data
As
Byte
(),
ByVal
offset
As
UInt32,
ByVal
size
As
UInt32)
For
i
As
UInteger
=
0
To
size
-
1
_value
=
Table(UInt32toByte(_value)
Xor
data(offset
+
i))
Xor
(_value
>>
8
)
Next
End Sub
'''
<summary>
获取CRC数据。
</summary>
Public
Function
GetDigest()
As
UInt32
Return
_value
Xor
UInt32.MaxValue
End Function
'''
<summary>
计算并获取CRC数据。(利用静态实例化实现)
</summary>
'''
<param name="data">
需要计算的数据组。
</param>
'''
<param name="offset">
偏移，一般设为0。
</param>
'''
<param name="size">
大小，一般设为数据组的Length。
</param>
Public
Shared
Function
CalculateDigest(
ByVal
data
As
Byte
(),
ByVal
offset
As
UInt32,
ByVal
size
As
UInt32)
As
UInt32
Dim
crc
As
New
ClsoCRC
'
crc.Init()
crc.Update(data, offset, size)
Return
crc.GetDigest
End Function
'''
<summary>
校验摘要
</summary>
'''
<param name="digest">
摘要
</param>
'''
<param name="data">
数据组
</param>
'''
<param name="offset">
偏移
</param>
'''
<param name="size">
大小
</param>
Private
Shared
Function
VerifyDigest(
ByVal
digest
As
UInt32,
ByVal
data
As
Byte
(),
ByVal
offset
As
UInt32,
ByVal
size
As
UInt32)
As
Boolean
Return
CalculateDigest(data, offset, size)
=
digest
End Function
'''
<summary>
返回BYTE (CLE添加)
</summary>
Private
Shared
Function
UInt32toByte(
ByVal
UInt32Value
As
UInteger
)
As
Byte
Return
UInt32Value
Mod
256
End Function
End Class