[VidHack]

Hello All,

Been messing with X-Plane UDP packets, and if your a VB6 coder, you will know what a hastle converting a FLOAT Value is. Most of you migrate over to JeffLewis.net and check out his VB6 code, heck, thats what I did. I decided to see if I could optimize his ConvertBytes2Float Function, so for all you VB6 coders replace Jeff's subroutine with this code, I got a 180% increase in speed!! I even made a pure 'c' DLL with this function Exported, still could not beat this in-line code. Here is a screenshot of it in action. Hopefully I gave all the credit where due.

Function ConvertBytesToFloat(byte1 As Byte, byte2 As Byte, byte3 As Byte, byte4 As Byte) As Single
  
'---------------------------------------------------------------
   'This sub converts four bytes to a single precision floating point value
   'VB6 has NO built in function for this. Thanks to Jeff Lewis for explaining the Conversion.
   'Original code from - > From Jeff Lewis, Jefflewis.net
   'I used some optimized Subs from VBspeed Website and a few VB speed tips, and got a 180% increase in speed!!
   'Using the VB Speed Template to check speed, went from 120 ticks down to 43 Ticks to convert 50,000 Floats!
   'Enjoy - VidHack V.1 Feb 07
'---------------------------------------------------------------
'CREDITS for the VB Speed Template Tester - NO Code Used, Just used to Test the Optimized Code.
'---------------------------------------------------------------
'Pop-up results, priority, formatting, precision timer,
' commenting, and other stuff added by Spodi.
' http://www.vbgore.com
'
'This program was originated from Almar Joling's template -
' credits go to him for the original idea and design.
' http://www.persistentrealities.com/vbfibre/
'----------------------------------------------------------------
 
'CODE STARTS HERE......
 
  Dim float As Single
  
  If byte1 = 0 And byte2 = 0 And byte3 = 0 And byte4 = 0 Then
    'Convert the float to 0, instead of 5.87747175411144E-39
     float = 0
  Else
  
   Dim NumberString1  As String
   Dim NumberString2  As String
   Dim NumberString3  As String
   Dim NumberString4  As String
   Dim CombinedString As String
   Dim BiasedExponent As Integer
   Dim Mantissa       As Double
   Dim ctr            As Integer
  
        NumberString1 = ByteToBit11(byte1)
        NumberString2 = ByteToBit11(byte2)
        NumberString3 = ByteToBit11(byte3)
        NumberString4 = ByteToBit11(byte4)
      
        'NOTE: Removed the ENDIAN Reversal option! Since X-Plane 8.50, UDP sent MAC format Only.
        CombinedString = NumberString1 & NumberString2 & NumberString3 & NumberString4

  '  BiasedExponent = 0
    For ctr = 2 To 9
      If Mid$(CombinedString, ctr, 1) = "1" Then
        BiasedExponent = BiasedExponent + 2 ^ (9 - ctr)
      End If
    Next ctr
    BiasedExponent = BiasedExponent - 127
  
    Mantissa = 1
    For ctr = 10 To 32
      If Mid$(CombinedString, ctr, 1) = "1" Then
        Mantissa = Mantissa + 2 ^ -(ctr - 9)
      End If
    Next ctr

    float = Mantissa * 2 ^ BiasedExponent
    If Mid$(CombinedString, 1, 1) = "1" Then
      float = -float
    End If
  End If 'float=0
  
   ConvertBytesToFloat = float
  
End Function

Public Function ByteToBit10(ByVal B As Long) As String
' by Jost Schwider, jost@schwider.de, 20001228, rev 001
' based on ByteToBit02 by Donald, donald@xbeat.net, 20001206
' From VBspeed...

  ByteToBit10 = "00000000"
  If B And &H1& Then MidB$(ByteToBit10, 15&) = "1"
  If B And &H2& Then MidB$(ByteToBit10, 13&) = "1"
  If B And &H4& Then MidB$(ByteToBit10, 11&) = "1"
  If B And &H8& Then MidB$(ByteToBit10, 9&) = "1"
  If B And &H10& Then MidB$(ByteToBit10, 7&) = "1"
  If B And &H20& Then MidB$(ByteToBit10, 5&) = "1"
  If B And &H40& Then MidB$(ByteToBit10, 3&) = "1"
  If B And &H80& Then MidB$(ByteToBit10, 1&) = "1"
  
End Function

Public Static Function ByteToBit11(ByVal B As Long) As String
' by Jost Schwider, jost@schwider.de, 20001227
' From VBspeed...

  Dim i As Long
  Dim sByte(0 To 255) As String
  
  If i Then
    ByteToBit11 = sByte(B)
  Else
    For i = 0 To 255
      sByte(i) = ByteToBit10(i)
    Next i
      ByteToBit11 = sByte(B)
  End If
  
End Function

OK, after POSTING, the CODE was CUT OFF??? So this is useless, Sorry for the POST. Some kind of LIMIT on the CodeBox? Huh?

VidHack

 UDP_SCRN_Shot.jpeg (173.96K)
Number of downloads: 74

This post has been edited by VidHack: 28 February 2007 - 06:04 PM

[Sandy Barbour]

USP was a good idea, that allowed all developers access to Xplane.
It is a pity that UDP has been messed around so much between Xplane releases.

[VidHack]

Hello,

Just to end this Post, I sent the optimized code to JeffLewis.net. Also, whoever maintains this site, check for a patch/upgrade to this forum software, why can I paste multiple lines of code in the codebox, it shows FINE in the Preview pane, but then the Final Post its cut off?? Seems like a bug to me, try it out.... Would think the Preview Pane would warm me of the Character Limit?? Also, speaking of crashes, I wanted to stress test the optimized code for a Buffer-Overflow, so I fired up X-Plane 8.60, turned on my UDP packet decoder, and selected 92 ->YES "92" data outputs, well, X-Plane did NOT like that, gave me a warning... See screenshot, then instead of returning me to the Data Output Tab, X-Plane justs shuts down. Come on, how about a simple check for outputs>92 then warn and return to App. Not die. Thought UDP did a round-robin of the buffered outputs, segmented the packet, then continued -? Guess not.
Man, I know, how about some cheese with my Wine.....

VidHack

 UDP_Crash.JPG (27.55K)
Number of downloads: 38

[Sandy Barbour]

Hi Vidhack

There is a limit of 2800 bytes.

Most errors in Xplane cause it to exit, which, IMO, is not always necessary.

This post has been edited by Sandy Barbour: 06 March 2007 - 03:43 AM