Question

I am looking for a effective/efficient way in VB6 to take a byte array split it into “chunks” and write each “chunk” to a file. The reason behind this is so that as each “chunk” gets written I can call RaiseEvent WriteProgress(BytesDone, BytesTotal) in order to update a progress bar elsewhere. Any suggestions on loop structure etc. is much appreciated.

Answer 1

CopyMemory is a fast way to extract an array chunk;

Private Declare Function CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (dest As Any, src As Any, ByVal length As Long) As Long

Const CHUNKSIZE = 3&

Dim offset As Long
Dim total  As Long
Dim copied As Long
Dim copy   As Long

Dim testBuff() As Byte: testBuff = StrConv("Klaatubaradanikto", vbFromUnicode)

total = 1 + UBound(testBuff)

'//write buffer
ReDim buff(CHUNKSIZE - 1) As Byte

Open "out.bin" For Binary Access Write As #1

For offset = 0 To -Int(-total / CHUNKSIZE) - 1 '//ghetto round-up
    If (copied + CHUNKSIZE) > total Then
        copy = total - copied
        ReDim buff(copy - 1)
    Else
        copy = CHUNKSIZE
    End If
    '//copy array segment to buffer
    CopyMemory buff(0), testBuff(offset * CHUNKSIZE), copy 
    '//write buffer
    Put #1, , buff

    copied = copied + copy
    Debug.Print offset, "copied:", copied, "of", total
    Next
Close #1