OpenEuphoria

RE: Using shared objects

• Posted by Ron Weidner <nova812 at hotmail.com> Jun 03, 2005
• 886 views

Thank you! Your code worked perfectly.  

I didn't test on Windows.  (I don't have a windows box
at the moment to test on) So I'm not sure about the 
whole bit about ...

__declspec(dllexport) void __stdcall

But, if I had to guess, (and this is only a guess) you
should only need that stuff if and only if you are
using a c++ compiler as opposed to a c compiler.  I
compiled the dog.so using GCC which is a C compiler 
and didn't need to make any changes to the C code. I
suspect if I compiled using g++, I would need to 
make some changes.

I studied your code, cross referenced it with the eu docs, 
and now I'm goint to take a crack at explaining it.  Let
me know if I'm close.

atom dogLib  -- used like a pointer
-- You would need to use "./dog.so" here if dog.so 
-- is actually in the current directory or you could
-- use ./somedir/dog.so if the .so is nested deeper
-- relative to the current directory 

-- load the dll and return a pointer to its mem location
dogLib = open_dll("./dog.so")  

-- This is like porting the C header files to Euphoria
constant
mush_ = define_c_proc(dogLib, "mush", {C_POINTER, C_INT}),
bark_ = define_c_func(dogLib, "bark", {}, C_INT)

global procedure mush(sequence p)
    atom lp         -- used as a pointer
    sequence lps    -- used as an array of pointers
integer len     -- len of p where p is expected to be a sequence of
    sequences
    len = length(p)
    
    -- create a pointer to a block of mem 4 bytes long * the len of p
    -- the reason for 4 bytes is because that's the size of a pointer
    lp = allocate(len * 4) 
    
    -- delete any garbage in the memory locations
    lps = repeat(0, len)
    
    -- start making pointers to each sequence in p
    for loop = 1 to len do
        
	-- allocate enough mem for p[loop] + 1, strcpy the val
	-- in p[loop] & "\0" to that location and return a
	-- pointer to it.
        lps[loop] = allocate_string(p[loop]) 
	
    end for
    
    -- poke4(atom where_p, object what)  
    -- put the 4 pointers just created into the lp mem location
    poke4(lp, lps)
    
    -- call the c function (procedure since the C return val is void)
    c_proc(mush_, {lp, len}) 
    
    -- look ma... mem leaks in euphoria are posible. :)
    for loop = 1 to len do
        free(lps[loop])  -- free the strings
    end for
    
    free(lp)  -- free the mem storing pointers to the strings
end procedure -- how'd I do??

global function bark()
    return c_func(bark_, {})
end function