OpenEuphoria

1. How do you pass data in and out of Euphoria DLLs?

• Posted by axtens Oct 16, 2008
• 1056 views

G'day everyone

I'm developing a Euphoria DLL for use with VB6. How does one pass sequences out from the Euphoria end to the VB6 end?

So far I've worked out that I can pass in an atom that points to the first item of an array of long and fill out the array. I first have to ask the DLL how many longs there are, so that I don't pass in any array that's too small and end up with corrupted memory.

object resultObj 
 
global function resultSize() 
  if atom( resultObj ) then 
    return 1 
  else 
    return length( resultObj ) 
  end if 
end function 
 
global procedure getResult( atom ptr ) 
  if atom( resultObj ) then 
    poke4( ptr, resultObj ) 
  else 
    for i = 1 to length( resultObj ) do 
      poke4( ptr, resultObj[ i ] ) 
      ptr += 4 
    end for 
  end if 
end procedure 

It's similar to a technique I developed for reading BSTRs that have been passed in using StrPtr(), as below:

function peek_vb( atom ptr ) 
    sequence str, temp, len 
     
    str = "" 
     
    ptr -= 4 
    len = peek( {ptr,4} ) -- get length DWORD 
    ptr += 4 
     
    temp = peek( {ptr, 2} ) 
    ptr += 2 
    while not equal( temp, {0,0} ) do 
        str &= ( temp[2] * 256 + temp[1] ) 
        temp = peek( {ptr,2} ) 
        ptr += 2 
    end while 
    return { bytes_to_int(len) / 2 , str } 
end function 

The context for all this is that I'm wrapping Mike Sabal's HexMath.e.

Is this all that there is available, or are there other techniques available for returning sequences?

Kind regards, Bruce.

3. Re: How do you pass data in and out of Euphoria DLLs?

• Posted by axtens Oct 16, 2008
• 1010 views

Okay, I'll give that a shot as well. But later, as it's just ticked past midnight here in Perth, WA, Australia.

Thanks for all your help thus far.

Kind regards,

Bruce.