OpenEuphoria

2. Re: Eu->dll on Windows, can't get it to work

• Posted by ghaberek (admin) Jun 01, 2016
• 1127 views

Compiling with GCC will produce CDECL code. Add a "+" to the name of your function, like this:

constant my_func_id = define_c_func( my_dll, "+my_func", {C_POINTER,C_INT}, C_INT ) 

Read more here: define_c_func.

What the manual doesn't tell you, and it's a really neat trick, is that it will safely ignore that leading "+" character on other platforms, so you don't need to have all sorts of silly ifdefs in your code for Windows or Linux.

-Greg

4. Re: Eu->dll on Windows, can't get it to work

• Posted by ghaberek (admin) Jun 01, 2016
• 1138 views

What version of Euphoria are you running?

-Greg

6. Re: Eu->dll on Windows, can't get it to work

• Posted by ghaberek (admin) Jun 01, 2016
• 1151 views

Does it work with the Beta 1 download? Maybe try building Euphoria from source?

I don't think those errors indicate a problem. I think that's more a problem with Dependency Walker than the library.

Nope. We voted that out years ago.

-Greg

8. Re: Eu->dll on Windows, can't get it to work

• Posted by ghaberek (admin) Jun 01, 2016
• 1153 views

I am also using 4.1 Beta 2. I did some debugging and it looks like it has to do with heap allocation. See the segfault at the end of the debugging output below.

I would try going back to Beta 1 or build from source and see if it's still a problem. I couldn't find any open tickets about this so we may have found a bug.

-- dll_test.e 
 
public function add_two( atom value ) 
    return (value + 2) 
end function 
  
public procedure print_hex( atom value ) 
    printf( 1, "#%08x\n", value ) 
end procedure 

-- test_dll.ex 
include std/dll.e 
include std/machine.e 
 
atom dll_test = open_dll( "dll_test.dll" ) 
printf( 2, "dll_test = #%08x\n", dll_test ) 
 
constant add_two = define_c_func( dll_test, "+add_two", {E_ATOM}, E_ATOM ) 
printf( 2, "add_two = %d\n", add_two ) 
 
constant print_hex = define_c_proc( dll_test, "+print_hex", {E_ATOM} ) 
printf( 2, "print_hex = %d\n", print_hex ) 
 
atom value = rand( 100 ) 
printf( 2, "value = %d\n", value ) 
 
value = c_func( add_two, {value} ) 
printf( 2, "add_two( value ) = %d\n", value ) 
 
puts( 2, "print_hex( value ) = " ) 
c_proc( print_hex, {value} ) 

>euc -dll dll_test.e 
Build directory: build-715921\ 
Translating code, pass: 1 2 3  generating 
Compiling with GCC 
Compiling  13% init-.c 
Compiling  50% dll_test.c 
Compiling  75% main-.c 
Linking 100% ..\dll_test.dll 

>gdb32 eui 
GNU gdb (GDB) 7.9.1 
Copyright (C) 2015 Free Software Foundation, Inc. 
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> 
This is free software: you are free to change and redistribute it. 
There is NO WARRANTY, to the extent permitted by law.  Type "show copying" 
and "show warranty" for details. 
This GDB was configured as "mingw32". 
Type "show configuration" for configuration details. 
For bug reporting instructions, please see: 
<http://www.gnu.org/software/gdb/bugs/>. 
Find the GDB manual and other documentation resources online at: 
<http://www.gnu.org/software/gdb/documentation/>. 
For help, type "help". 
Type "apropos word" to search for commands related to "word"... 
Reading symbols from eui...done. 
(gdb) run test_dll.ex 
Starting program: C:\Euphoria\bin\eui.exe test_dll.ex 
[New Thread 15932.0x1bc4] 
[New Thread 15932.0x2ac0] 
[New Thread 15932.0x2fd4] 
[New Thread 15932.0x114c] 
dll_test = #71180000 
value = 87 
 
Program received signal SIGSEGV, Segmentation fault. 
0x00000001 in ?? () 
(gdb) bt 
#0  0x00000001 in ?? () 
#1  0x0000001c in ?? () 
#2  0x8014cc8c in ?? () 
#3  0x76ecdecb in ntdll!RtlAllocateHeap () from C:\Windows\SYSTEM32\ntdll.dll 
Backtrace stopped: previous frame inner to this frame (corrupt stack?) 

-Greg

10. Re: Eu->dll on Windows, can't get it to work

• Posted by petelomax Jun 02, 2016
• 1119 views

Just a few months ago, I had reason to investigate the E_XXX constants, and ended up writing this (draft):

One thing that definitely affects Phix, but I can't say about OE, is that if a dll were compiled with it's own copy of the heap manager, then if any function in the dll allocated something and returned it to the calling exe, the latter would most probably try and release it in the wrong heap, which would end pretty badly. I also noted that delete_routine and friends would be utterly hosed, at least for Phix.

The only way I could see round the problem (in Phix) would be that Phix-compiled .dll/so files [when implemented!] should be restricted to C_INT(etc)/C_FLOAT/C_DOUBLE/C_POINTER and in the latter case, should my_dll return a pointer to some memory it had allocated, the calling code would need to my_dll_free(ptr) it after it had retrieved a copy of the returned data.

Likewise the parameters to any dll routine would need restricting to atoms, exactly like call_back.

Pete

12. Re: Eu->dll on Windows, can't get it to work

• Posted by AndySerpa Jun 02, 2016
• 1091 views

Just to repeat, although I did get a simple function that passes an integer back and forth to work, it will also crash without passing (or returning) any parameters at all depending on what it did, or that same function that was working will fail just by adding a print statement.

e.g. the function

function simpletest(integer x) 
return x+1 
end function 

works. But this crashes:

function simpletest(integer x) 
? x 
return x+1 
end function 

So the problem seems larger than Euphoria data types.