OpenEuphoria

2. Re: Wrapping a C library.

• Posted by useless_ Jan 16, 2012
• 2134 views

Did you look at

http://rapideuphoria.com/cgi-bin/asearch.exu?dos=on&win=on&lnx=on&gen=on&keywords=plot

?

useless

4. Re: Wrapping a C library.

• Posted by mattlewis (admin) Jan 16, 2012
• 2127 views

Yes, you'll need to compile that yourself, although it looks fairly simple. I tried downloading it, and it's a single file. After extracting it, I went into the source directory and did:

gnuplot_i-2.10/src$ gcc -fPIC gnuplot_i.c -shared -o gnuplot_i.so 

That built the shared library for me, and should work for you. One note: if you're on a 64-bit system, but using 32-bit euphoria, you'll want to tell gcc to use the -m32 flag:

gnuplot_i-2.10/src$ gcc -m32 -fPIC gnuplot_i.c -shared -o gnuplot_i.so 

Then you should be able to wrap the library. Looking at the API, it mostly takes pointers to values (which is what the asterisks mean in C), so make sure that you're allocating and passing pointers. If you have specific questions, please ask!

Matt

6. Re: Wrapping a C library.

• Posted by ChrisB (moderator) Jan 16, 2012
• 2020 views

Wow Greg, that took you 5 hours.

Now go away and write me an wrapper, and a complete set of dlls and a manual for Luxinia

http://www.luxinia.de/index.php/Main/HomePage

I'll give you 24 hours for this one!

Chris

8. Re: Wrapping a C library.

• Posted by ghaberek (admin) Jan 16, 2012
• 2055 views

Actually it only took about an hour. 90% of it was already written, I just glued it all together. With all this recent discussion on wrapping C libraries, I think I'm going to start compiling a good how-to on the subject. I'm also thinking about writing an app that will assist with the process of wrapping a large library, which would be useful for Luxinia, or even wxEuphoria.

It hadn't already been written, I built it somewhere in the time between your post and Matt's post.

This is actually a good example of a very simple wrapper. Unfortunately it's not always this easy.

-Greg

10. Re: Wrapping a C library.

• Posted by ghaberek (admin) Jan 16, 2012
• 2054 views

Do you mean FLTK? (Fast, Light Toolkit)

Have you had a look at wxEuphoria at all? It's really quite simple to use.

-Greg

12. Re: Wrapping a C library.

• Posted by ghaberek (admin) Jan 16, 2012
• 2050 views

EZWGL V1.50 is released on Dec 6, 1999 

I'm not sure it's worth wrapping a toolkit which was last updated over 12 years ago.

I've honestly never used EuWinGUI. I started with Win32Lib and then got into wxEuphoria early on. To use Win32Lib or wxEuphoria is quite simple: create() your controls, set up your event handlers setHandler()/set_event_handler(), and then call your main function WinMain()/wxMain(). I think EuWinGui works the same way, doesn't it? FLTK might be worth a good look, and Jeremy recently wrapped IUP as well.

-Greg

14. Re: Wrapping a C library.

• Posted by Davy Jan 17, 2012
• 1873 views

Greg,

I'm getting a type check error when I use the gnuplot_plot_xy() function.

Looking at the include file, I see that the parameters x and y are atoms, however, writing the euphoria equivalent of the example given in the documentation:

 gnuplot_ctrl    *h ; 
    double          x[50] ; 
    double          y[50] ; 
    int             i ; 
 
    h = gnuplot_init() ; 
    for (i=0 ; i<50 ; i++) { 
        x[i] = (double)(i)/10.0 ; 
        y[i] = x[i] * x[i] ; 
    } 
    gnuplot_plot_xy(h, x, y, 50, "parabola") ; 
    sleep(2) ; 
    gnuplot_close(h) ; 

was when I got the error.

I took it that x and y being arrays here, then in the corresponding Eu code x and y would be sequences.

I think this is something to do with the fact that x and y are not actually arrays, but pointers to arrays. Unfortunately my knowledge of C is nil so I'm just confused...

Here is the code generating the error -

include "gnuplot_i.e" 
include std/console.e 
sequence x, y  
 
x = {} 
y = {} 
gnuplot_ctrl g = gnuplot_init() 
 
for i = 0.1 to 5 by 0.1 do 
    x &= i 
    y &= i*i 
end for 
 
gnuplot_plot_xy(g, x, y, 50, "parabola") 
 
any_key() 
gnuplot_close( g ) 

include std/convert.e 
include std/machine.e 
 
sequence x = repeat( 0, 50 ) 
atom x_array = allocate( length( x ) * 8 ) -- doubles are 8 bytes each 
 
-- write your sequence into an array: 
for i = 1 to length( x ) do 
    poke( x_array + (i-1) * 8, atom_to_float64( x[i] ) ) 
end for 
 
-- read the array in memory into a sequence: 
for i = 1 to length( x ) do 
    x[i] = float64_to_atom( peek( { x_array + (i-1) * 8, 8 } ) 
end for 

16. Re: Wrapping a C library.

• Posted by Davy Jan 17, 2012
• 1864 views

Ah, thanks Matt. I'll do what you suggest and add the appropriate code to gnuplot_i.e, then I can use sequences in the gnuplot function calls.

18. Re: Wrapping a C library.

• Posted by ghaberek (admin) Jan 17, 2012
• 1859 views

Okay, I've made the necessary changes, added a second example program, and posted the code to my BitBucket repository. I also renamed this project to eugnuplot so it's easier to identify.

https://bitbucket.org/ghaberek/eugnuplot

Oh, and here's the routine I used for allocating an array of float64 values.

function allocate_float64_array( object data, integer count=-1 ) 
 
    -- make sure we have an array of values 
    if atom( data ) then 
        data = {data} 
    end if 
 
    -- auto-detect the array length, if necessary 
    if count = -1 then 
        count = length( data ) 
    end if 
 
    -- allocate the block of memory 
    atom ptr = allocate( count * 8 ) 
 
    -- poke the values into memory 
    for i = 1 to count do 
        poke( ptr + (i-1) * 8, atom_to_float64( data[i] ) ) 
    end for 
 
    -- return the data pointer 
    return ptr 
end function 

-Greg

20. Re: Wrapping a C library.

• Posted by Davy Jan 22, 2012
• 1763 views

Greg, sorry to be a pain, but I want to use gnuplot_i.e with an older program written in 3.1.1; I'm not sure which statements I need to remove to make the include file backwards compatible. I'm still finding my way around ver 4.x, but obviously I need to remove the "override" functions and references to the standard library.
Forked into: 3.1.1 backwards compatibility

22. Re: Wrapping a C library.

• Posted by Davy Jan 24, 2012
• 1685 views

Once again Greg, many thanks for your time and effort. I'm sure there will be others who haven't yet made the switch to 4.x who will appreciate it.

One error found in the new include file: "public" should be changed to "global" in the constant declaration. Apart from that, perfect!