Use new DLL - IM Barcodes

[ShelbySue]

I have the following sample C code calling this dll (attached) and can't figure out about sending and getting parameters. This looks like pointers and I am not sure how that translates to AU code. I have my sample code below. I am getting a blank $return - the same as I am sending:

char TrackString[21]; /* Input parameter Track String + 1 null*/
char RouteString[12]; /* Input parameter Route String + 1 null*/
char BarString[66]; /* Output parameter Bar String + 1 null */

int RetCode; /* Return code from the usps4cb encoder */

int USPS4CB( char *TrackPtr, char *RoutePtr, char *BarPtr);

memcpy(TrackString,"01234567094987654321",20);
TrackString[20] = '\0';

memcpy(RouteString,"01234567891",11);
RouteString[11] = '\0';

memset(BarString, ' ', sizeof(BarString)); /* Prime with blanks! */
BarString[65] = '\0'; 

RetCode = USPS4CB(TrackString,RouteString,BarString);

printf("Outputs are:\n"); /* Print the outputs */
printf("USPS4CB RetCode is: %i\n",RetCode);
printf("Encoded Bar String is: %s\n",BarString);

AU3 Test Code:( $return2 = 0 means it worked and translated the the barcode data)

#include <String.au3>

$Result = _StringRepeat(" ",65)
$start= '82205455868913559972'
$next = '01234567891'

$dll = dllopen("usps4cb.dll")


$result2 = dllcall($dll,'str',$start,'str',$next, 'str', $Result )
msgbox(0,"Call Result",$result2)
msgbox(0,"Barcode Response","[" & $result & "] Length=" & StringLen($result) )

usps4cb.dll

[Richard Robertson]

Well, first off, you forgot to list the function name in your DllCall. How do you expect it to call the function that it doesn't have the name for?

DllCall ( "dll", "return type", "function" [, "type1", param1 [, "type n", param n]] )

Also remember, DllCall returns an array.

If the function call fails then @error is set to 1. Otherwise an array is returned that contains the function return value and a copy of all the parameters (including parameters that the function may have modified when passed by reference).

$return[0] = function return value

$return[1] = param1

$return[2] = param2

...

$return[n] = paramn

Also, you have to declare a buffer ahead of time, for the function to fill in.

Try this instead and see if it works.

#include <String.au3>

$Result = DllStructCreate('char[66]')
DllStructSetData($Result, 1, _StringRepeat(' ', 65))
$start= '82205455868913559972'
$next = '01234567891'

$dll = dllopen("usps4cb.dll")

$result2 = dllcall($dll, 'int', 'USPS4CB', 'str', $start, 'str', $next, 'ptr', $Result)
msgbox(0, "Call Result", $result2[0])
msgbox(0, "Barcode Response", "[" & $Result & "] Length=" & StringLen($Result))

[ProgAndy]

You don't need to create the Buffer. AutoIt does that for you, but the Stringis only changed in the Returned Array, not in the Parameter-Variable. The Dll needs cdecl, too: -> Retrun type: "int:cdecl"

So you have to call the DLL this way:

CODE

#include <String.au3>

$Result = _StringRepeat(" ",65)

$start= '82205455868913559972'

$next = '01234567891'

$result2 = dllcall("usps4cb.dll","int:cdecl","USPS4CB",'str',$start,'str',$next, 'str', $Result )

If @error Then

MsgBox(0, "Dllcall Error:", @error)

Else

; The Parameters are returned in the Return-array, so use $result2[3] for third parameter

msgbox(0,"Call Result",$result2[0])

msgbox(0,"Barcode Response","[" & $result2[3] & "] Length=" & StringLen($result2[3]) )

EndIf

Edited June 2, 2008 by ProgAndy

[Richard Robertson]

I didn't think AutoIt would create the buffer. I've always felt more safe making buffers myself though. Years of having to has taught me that. My other arguments were sound though.

[ShelbySue]

BINGO - DINGO!

Thanks guys - the addition of int:cdecl made the call and returned the correct (changed) data in the $result2[3] location.

How did you know the int:cdecl was needed instead of just int ?

I can't believe I forgot the function! This is my first attempt at utilizing a dll that has not already been used by someone on the forum and, when it didn't work the first few tries, I freaked out and came to the forum.

But, then, that is what this community is for?

Thanks again.

[Richard Robertson]

I can only assume that ProgAndy downloaded the dll and viewed a dump of some manner.

[ptrex]

@all

You can create barcode in AU3 without external DLL files.

Barcode in AU3

regards

ptrex

[Richard Robertson]

I doubt the dll just makes a barcode. I'm sure there's some sort of processing involved, a lookup maybe.