Binary search for ANSI string

[Elroy]

I've already got this working, but very inefficiently.

I need to search for an ANSI string in a Binary file. The file will already be opened as Binary.

Currently, I'm reading in chunks, and then converting those chunks to Unicode, and then using Instr against my search string.

I'd much prefer to convert my "sNeedle" string to a byte array, and do the search without messing with Unicode, but I don't have an algorithm to search for a byte array within a much larger byte array, which is what I need.

I took a look at InstrB, but I've never used that and I'm not sure how it works. I did do the following test, but it didn't do anything useful (always returning 0).

Option Explicit

Private Sub Form_Load()

    Dim bb() As Byte
    ReDim bb(3)
    bb(0) = 5
    Dim bb2() As Byte
    ReDim bb2(100)
    bb2(44) = 5

    Debug.Print InStrB(bb, bb2)

End Sub

Any ideas/suggestions?

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p.s. I suppose I could write loops to do my search, but I'm not sure that'd be any faster than what I'm doing.

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Here, I'll post what I'm doing (but don't like):

Private Function BinaryFileSearch(hFle As Integer, sSearchString As String, _
                                  Optional iStartPosition As Long = 1&, _
                                  Optional iFoundPosition As Long) As Boolean
    ' Returns true if sSearchString is found, else false.
    ' sSearchString can be no longer than 128.
    ' The lFoundPosition is a return argument.
    '    It returns the latest position before lStartPosition (if there isn't one after lStartPosition) or
    '    it returns the earliest position after lStartPosition.
    '
    Dim sFileData   As String
    Dim pFile       As Long
    Dim iLen        As Long
    Dim iPos        As Long
    '
    sFileData = Space$(1024&)
    iLen = LOF(hFle)
    pFile = iStartPosition
    Do
        If pFile > iLen Then Exit Do
        Get hFle, pFile, sFileData
        iPos = InStr(sFileData, sSearchString)
        If iPos <> 0& Then
            iFoundPosition = pFile + iPos - 1&
            If iFoundPosition >= iStartPosition Then
                BinaryFileSearch = True
                Exit Do
            End If
        End If
        pFile = ((pFile + 1024&) - Len(sSearchString)) + 1&
    Loop
End Function