How to operate with binary files faster? - vb.net

Question

What I'm trying to do:
Open two binary files, each 64 MB
Take first half of each byte of each file and combine those halves in 1 bytes same with second half, for example: first byte in first file is 0x51, in second file its 0xA2, so I need write two bytes in third file which are 0x5A and 0x12, same for whole bytes, therefore final length in third file will be 128 MB.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles
Button1.Click
Try
' choosing first file
OpenFileDialog1.FileName = "First file"
OpenFileDialog1.Title = "Choose the Address.bin file"
OpenFileDialog1.Filter = "bin files (*.bin)|*.bin|All files
(*.*)|*.*"
If OpenFileDialog1.ShowDialog() = Windows.Forms.DialogResult.OK
Then
Label1.Text =
System.IO.Path.GetFullPath(OpenFileDialog1.FileName)
Else
Exit Sub
End If
Catch ex As Exception
End Try
Try ' choosing first file
OpenFileDialog1.FileName = "Second FIle"
OpenFileDialog1.Title = "Choose the Flash.bin file"
OpenFileDialog1.Filter = "bin files (*.bin)|*.bin|All files (*.*)|*.*"
If OpenFileDialog1.ShowDialog() = Windows.Forms.DialogResult.OK Then
Label2.Text = System.IO.Path.GetFullPath(OpenFileDialog1.FileName)
Else
Exit Sub
End If
Catch ex As Exception
End Try
Dim firstFileByte(1) As Byte
Dim SecondFileByte(1) As Byte
Dim Result As String
Dim Result2 As String
Dim Final(1) As Byte
For i = 0 To FileLen(Label1.Text) - 1
Using FirstFile As New FileStream(Label1.Text, FileMode.Open) 'save
'FIRST DIGIT********************************************************************************************
FirstFile.Seek(i, SeekOrigin.Begin)
FirstFile.Read(firstFileByte, 0, 1)
'TextBox1.Text = final(0).ToString("X")
Using SecFile As New FileStream(Label2.Text, FileMode.Open) 'save
SecFile.Seek(i, SeekOrigin.Begin)
SecFile.Read(SecondFileByte, 0, 1)
End Using
Result = firstFileByte(0).ToString("X2").Substring(0, 1) & SecondFileByte(0).ToString("X2").Substring(0, 1) ' comobining frist half of the first file and second file
Result2 = firstFileByte(0).ToString("X2").Substring(1, 1) & SecondFileByte(0).ToString("X2").Substring(1, 1) ' comobining second half of the first file and second file
End Using
Using vFs As New FileStream(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) & "\Result.bin", FileMode.Append) ' save
TextBox1.Text = Result2
'Dim FileLenVar As UInt32 = FileLen(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) & "\Result.bin") - 1
Final(0) = Convert.ToByte(Result, 16) 'converting result to the byte
Final(1) = Convert.ToByte(Result2, 16)
vFs.Write(Final, 0, 1)
vFs.Write(Final, 1, 1)
End Using
Next
End Sub
It works, but takes a lot of time: it writes 1 MB in 1 minute. How can I optimize it?

Answer 1

The files are small enough to load into RAM for processing. Processing the data in RAM can minimise the disk I/O needed, the latter very often being the slowest part of a program, especially if it is done in very small pieces like individual bytes. As also noted by Ben Voigt, string operations are somewhat slower than numeric operations.
Here's a simple demonstration of what could be done:
Imports System.IO
Module Module1
Dim f1 As String = "C:\temp\A.bin"
Dim f2 As String = "C:\temp\B.bin"
Dim outFile As String = "C:\temp\C.bin"
Sub CombineFiles()
Dim a1 = File.ReadAllBytes(f1)
Dim a2 = File.ReadAllBytes(f2)
Dim c(a1.Length + a2.Length - 1) As Byte ' c for combined
Dim highBits As Byte = &HF0
Dim lowBits As Byte = &HF
For i = 0 To c.Length - 1 Step 2
c(i) = a1(i \ 2) And highBits Or a2(i \ 2) >> 4
c(i + 1) = a1(i \ 2) << 4 Or a2(i \ 2) And lowBits
Next
File.WriteAllBytes(outFile, c)
End Sub
Sub CreateTestFiles()
'TODO: be more creative with the generated data.
Dim nBytes = 64
Dim a(nBytes - 1) As Byte
For i = 0 To nBytes - 1
a(i) = &H12
Next
File.WriteAllBytes(f1, a)
For i = 0 To nBytes - 1
a(i) = &HAB
Next
File.WriteAllBytes(f2, a)
End Sub
Sub Main()
'CreateTestFiles()
CombineFiles()
End Sub
End Module
Of course, you'd check that the input files were of equal length, and check for any other possible problems ;)