Re: [Chicken-users] passing variable number of floats to C

[Kon Lovett]

On Feb 19, 2008, at 11:32 AM, Heinrich Taube wrote:

> thanks, i see now. since its a list it would be nice from the users  
> perspective to be able to pass immediate ints in addition to floats  
> without having to cons the floats on the scheme side. so on the c  
> side ill have to make sure that the car is either an int or a float  
> before i access it -- ive been poking around in the doc but dont  
> see any obvious predicates to do this.

The "C Interface" section (http://galinha.ucpel.tche.br/C% 
20interface) is incomplete. This should be a To Do item. For now look  
in the source @ "chicken.h".

> can you please point me in the right direction? thanks for your help!
>
> for ( ; C_SCHEME_END_OF_LIST != lyst; lyst = C_u_i_cdr( lyst )) {
>  if ( IS_INT(C_u_i_car(lyst)) )
>    sum += (double)C_u_i_car(lyst) ;
>  else if ( IS_FLOAT(C_u_i_car(lyst))
>    sum += C_u_i_car(lyst) ;
> }

/*
C_truep used here since the predicate macros - F_foop - have Chicken  
Scheme boolean results,
not C.
*/

double sum = 0.0;
for ( ; C_SCHEME_END_OF_LIST != lyst; lyst = C_u_i_cdr( lyst )) {
    C_word word = C_u_i_car( lyst );
    if (C_truep( C_flonump( word ) )) {
        sum += C_flonum_magnitude( word );
    } else if (C_truep( C_fixnump( word ) )) {
        sum += (double) C_unfix( word );
    }
}

If we were only interested in integers then "C_num_to_int" could be  
used.

> > But this works:
> >
> > #>
> > static double
> > double_sum( C_word lyst )
> > {
> >   double sum = 0.0;
> >   for ( ; C_SCHEME_END_OF_LIST != lyst; lyst = C_u_i_cdr( lyst )) {
> >     sum += C_flonum_magnitude( C_u_i_car( lyst ) );
> >   }
> >   return sum;
> > }
> > <#

Best Wishes,
Kon