Adler32 Checksumme berechnen

    • VB.NET

      Adler32 Checksumme berechnen

      Hier ist eine Klasse dich ich von C# nach Vb.Net übersetzt und modifiziert habe. Sie berechnet die Adler32-Checksumme eines Buffers oder Streams.

      VB.NET-Quellcode

      1. Public Class Adler32
      2. Private Const Base As Integer = 65521
      3. Private _Checksum As Long
      4. Public ReadOnly Property Checksum() As Long
      5. Get
      6. Return _Checksum
      7. End Get
      8. End Property
      10. Public Sub New()
      11. _Checksum = 0
      12. End Sub
      14. Public Sub Clear()
      15. _Checksum = 0
      16. End Sub
      18. Public Sub Update(ByVal value As Integer)
      19. Dim s1 As UInt32 = _Checksum And &HFFFF
      20. Dim s2 As UInt32 = _Checksum >> 16
      22. s1 = (s1 + (CUInt(value) And &HFF)) Mod Base
      23. s2 = (s1 + s2) Mod Base
      25. _Checksum = (s2 << 16) + s1
      26. End Sub
      27. Public Sub Update(ByVal buffer As Byte(), ByVal offset As UInt32, ByVal count As Integer)
      28. If buffer Is Nothing Then
      29. Throw New ArgumentNullException("Buffer")
      30. End If
      31. If count < 0 Then
      32. Throw New ArgumentOutOfRangeException("Count", "cannot be negative")
      33. End If
      34. If offset + count > buffer.Length Then
      35. Throw New ArgumentOutOfRangeException("Offset AndOr Count")
      36. End If
      38. Dim s1 As UInt32 = _Checksum And &HFFFF
      39. Dim s2 As UInt32 = _Checksum >> 16
      41. While count > 0
      42. Dim n As Integer = 3800
      43. If n > count Then
      44. n = count
      45. End If
      46. count -= n
      48. n -= 1
      49. While n >= 0
      50. s1 = s1 + CUInt(buffer(offset) And &HFF)
      51. s2 = s2 + s1
      52. offset += 1
      53. n -= 1
      54. End While
      55. s1 = s1 Mod Base
      56. s2 = s2 Mod Base
      57. End While
      59. _Checksum = (s2 << 16) Or s1
      60. End Sub
      61. Public Sub Update(ByVal Stream As FileStream, ByVal count As Integer)
      62. If Stream Is Nothing Then
      63. Throw New ArgumentNullException("Buffer")
      64. End If
      65. If count < 0 Then
      66. Throw New ArgumentOutOfRangeException("Count", "cannot be negative")
      67. End If
      68. If Stream.Position + count > Stream.Length Then
      69. Throw New ArgumentOutOfRangeException("Offset AndOr Count")
      70. End If
      72. Dim s1 As UInt32 = _Checksum And &HFFFF
      73. Dim s2 As UInt32 = _Checksum >> 16
      75. While count > 0
      76. Dim n As Integer = 3800
      77. If n > count Then
      78. n = count
      79. End If
      80. count -= n
      82. n -= 1
      83. While n >= 0
      84. s1 = s1 + CUInt(Stream.ReadByte() And &HFF)
      85. s2 = s2 + s1
      86. n -= 1
      87. End While
      88. s1 = s1 Mod Base
      89. s2 = s2 Mod Base
      90. End While
      92. _Checksum = (s2 << 16) Or s1
      93. End Sub
      94. End Class


      Hier ein kleines beispiel wie man die Manifest-Checksumme einer GCF Datei berechnet:

      VB.NET-Quellcode

      1. Dim adler32 As New Checksums.Adler32
      2. adler32.Update(Stream, 48)'Die ersten 12 UInts berechnen
      3. For i = 1 To 8
      4. adler32.Update(0)'Die folgenden 2 Uints auslassen
      5. Next
      6. Stream.Position += 8
      7. adler32.Update(Stream, Manifest.Header.BinarySize - 56)'den rest berechnen


      Copyright: © 1999, 2000, 2001 Free Software Foundation, Inc. © 2001 Mike Krueger
      Translation and modification: Me (rAzoR8)
      Source: koders.com/csharp/fid630960EA3…CC79915FB359B62788D3.aspx

      Dieser Beitrag wurde bereits 1 mal editiert, zuletzt von „razor8“ ()

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