Porting code from VB6 to Bascom

pinkfloyd11 · Joined: 02 Jul 2007 Posts: 247

Dear Friends

I'm porting a program from VB6 to Bascom AVR.
Now when compile the follow code I have "Invalid Datatype Error"

MSCOMM1.Output = Chr(2) & Chr(3) & Chr(4)
Stringaloopback = Chr(2) & Chr(3) & Chr(4)

Which is the correct way in Bascom?

Thanks

Evert :-) · Joined: 18 Feb 2005 Posts: 2165

Bonjorno,

MSCOMM1.Output = Chr(2) & Chr(3) & Chr(4)
Print Chr(2) ; Chr(3) ; Chr(4)

Stringaloopback = Chr(2) & Chr(3) & Chr(4)
Stringaloopback = Chr(2) + Chr(3) + Chr(4)

That's it.

AdrianJ · Joined: 16 Jan 2006 Posts: 2483 Location: Queensland

Your second example will not work in Bascom. The compiler will only parse two variables per statement.

Stringaloopback = Chr(2) + Chr(3) + Chr(4)

has to be written

Stringaloopback = chr(2) + chr(3) 'combine the first two

Stringaloopback = Stringaloopback + chr(4) 'add the next one on

You often need some temporary variables to get over this limitation

pinkfloyd11 · Joined: 02 Jul 2007 Posts: 247

dear Friends,

1)
Error: type expected [string *1]
Error: type expected [string *30]
Why??

2)
Since I don't know the length of string "stringa_dati", since here there isn't string type like in VB, can I use a "big" string like String * 30 and after do a trim??

Declare Function Crc(byval Stringa_dati As String * 30) As String * 1

Function Crc(byval Stringa_dati As String * 30) As String * 1

stringa_dati=trim(stringa_dati)
........
Crc= chr(my computation)

End Function

AdrianJ · Joined: 16 Jan 2006 Posts: 2483 Location: Queensland

You will have to post a bit more of your code, so we can see where the errors occur.
But in general, you have to remember you are dealing with a *very* small processor by comparison with a PC. VB will allow you to define a string up to around 2 GB, essentially unlimited, for all practical purposes. RAM limitations in an AVR will never allow this. So you always have to define all your variables in advance, so the compiler can allocate space, and get a chance to warn you if you exceed the allowable RAM.
Yes of course you can define a string 'long enough' and then use only a small part of it.
One other thing, when passing strings to a Sub or Function, always pass ByRef, then you only pass the address of the string, and can use any part of it inside the Sub/Function. When you pass ByVal, the whole string needs to be put on the stack. You quickly run out of stack, even if Bascom allows it ( which I doubt )

pinkfloyd11 · Joined: 02 Jul 2007 Posts: 247

Dear Friends

the error are:

Type Expected [String * 1] in line 93
Type Expected [String * 30] in line 93

And this is the code

93: Declare Function Crc(byref Stringa_dati As String * 30) As String * 1

Public Function Crc(byref Stringa_dati As String * 30) As String * 1
Dim i As Integer
Dim somma As Integer
Dim Moltiplicatore As Integer

For i = 1 To Len(Stringa_dati)
somma = somma + Asc(Mid(Stringa_dati, i, 1))
Next

If ((somma / 256) - (Int(somma / 256))) = 0 Then
CRC = Chr(0)
Else
Moltiplicatore = Int(somma / 256) + 1
CRC = Chr((256 * Moltiplicatore) - somma)
End If

End Function

Luciano · Joined: 29 Nov 2004 Posts: 3149 Location: Italy

Hi,

Try the code below in the Bascom simulator.
Once you have done that, try to change BYVAL in BYREF.

Best regards,

Luciano