Re: [Chicken-users] return a pair of ints from a C function?

[Ivan Raikov]

To return fixnums, you can do:

C_word g2d_glyphs_baseline(struct G2dGlyphs* glyphs)
{
        C_word* a = C_alloc(C_SIZEOF_PAIR);
        C_return(C_pair (&a, C_fix(10), C_fix(256)));
}

To return a pair of flonums (which is what you are doing with
C_int_to_num), you need to allocate memory for the numbers thusly:


C_word g2d_glyphs_baseline(struct G2dGlyphs* glyphs)
{
    C_word* lst = C_alloc(C_SIZEOF_PAIR);
    C_word *a, *b;

    a = C_alloc (C_SIZEOF_FLONUM);
    b = C_alloc (C_SIZEOF_FLONUM);

    C_return (C_pair (&lst, C_int_to_num (&a, 10), C_int_to_num (&b, 256)));
}


"Shawn Rutledge" <address@hidden> writes:

> OK dumb question time again:  I'm trying to return a pair of fixnums
> from a C function.
>
> C_word g2d_glyphs_baseline(struct G2dGlyphs* glyphs)
> {
>       C_word* a = C_alloc(C_SIZEOF_PAIR + 8);
>       C_return(C_pair (&a, C_int_to_num(&a, 10), C_int_to_num(&a, 256)));
> }
>
> or maybe
>
> C_word g2d_glyphs_baseline(struct G2dGlyphs* glyphs)
> {
>       C_word* c_ret = C_alloc(C_SIZEOF_PAIR);
>       C_word* a = c_ret;
>       C_int_to_num(&a, 10);
>       C_int_to_num(&a, 256);
>       C_return(*c_ret);
> }