OpenEuphoria

Re: How can I pass an atom to a C function as C float or double

• Posted by jbrown105 at speedymail.org Sep 13, 2003
• 344 views

On Sat, Sep 13, 2003 at 10:49:25AM -0400, euman at bellsouth.net wrote:
> 
> I dont know what the deal is with my mail being delivered html.
> sorry folks, I'll get right on that problem too, didnt start till this
> morning.
> 
> Is this better Elliott? Robert?
> 
> (C DLL)
> her_dll
> float CRoutine( float parameter1, double parameter2 ); 
> 
> (Euphoria code)
> atom junk, x, y
> x = 0.45
> y = 0.4534 
> junk = allocate(16) -- 4 (float) + 8(Double)
> poke(junk, atom_to_float32(x))
> poke4(junk+4, atom_to_float64(y))
> 
> constant 
> Myfunction = define_c_func(her_dll,"CRoutine",{C_FLOAT, C_DOUBLE}, C_FLOAT)
> 
> f = c_func(Myfunction,{peek(junk),peek4u(junk+4)}) -- byref
> f = c_func(Myfunction,{junk,junk+4}) -- byval

Well, 

f = c_func(Myfunction, {junk,junk+4}) -- byREF

would work as byref, but then the declaration would have to be

constant
Myfunction = define_c_func(her_dll,"CRoutine",{C_POINTER, C_POINTER}, C_FLOAT)

and the C code would have to be

float CRoutine( float * parameter1, double * parameter2 ); 

As for byval, you dont need the allocate() nor the atom_to_floatXX(), just
call the function like so

f = c_func(Myfunction,{x, y})

> 
> Hope this is more correct than the last post I made after 16 hours
> behind this darn thing. Oh yeah, Thanks Elliott, Rob
> 
> Euman
> H2O Software, Inc.
> 
> 
> 
> TOPICA - Start your own email discussion group. FREE!

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