Convert VB to C++

I have some lines of VB- Code (around 200 lines), that do some calculations on Strings (add, Substract, multiply, divide and bit-shift ASCII-Characters). To enhance performance, i would like to have this lines coded in C++ for maximum speed. I need a function, that i can call from VB, that does this calculations. It should be used like: DecodedString = ConvertIt(UnDecodedString) To do this job, you must be familiar with VB and C++. Here are some lines of the code to be converted: preset_2S = "==================" src_len = Len(Source) - 4 src_first = 2 src_post = src_first + src_len src = src_first dst = dst_first Result = src_len destS = Mid$(Source, src_first + 1, 4) src = src + 4 dst = dst + 4 bytesUsed = bytesUsed + 4 destS = " " & Right$(destS, Len(destS) - 1) If validEncryptionCode(Asc(Mid$(Source, src_first + 1, 1))) Then setDecryptionCode CByte(Asc(Mid$(Source, src_first + 1, 1))) While (bytesUsed < src_len) If control_bits = 0 Then src = src + 2 control_word = Asc(Mid$(Source, src - 1, 1)) And 255 control_word = control_word Or (CLng(Asc(Mid$(Source, src, 1)) And 255) * 256) 'src = src + 1 control_bits = 16 bytesUsed = bytesUsed + 2 End If If (control_word And 1) <> 0 Then src = src + 2 offset = (Asc(Mid$(Source, src - 1, 1)) And 240) * 16 leng = (Asc(Mid$(Source, src - 1, 1)) And 15) + 1 On Error Resume Next If Len(Source) >= src Then offset = offset + (Asc(Mid$(Source, src, 1)) And 255) End If On Error GoTo err_handler bytesUsed = bytesUsed + 2 buffS = "" ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform WinXP, Win2000