In order to create an arbitrary precision floating point / drop in
replacement for Double, I'm trying to wrap MPFR (http://www.mpfr.org/)
using the FFI but despite all my efforts the simplest bit of code
doesn't work. It compiles, it runs, but it crashes mockingly after
pretending to work for a while.
I've done an interface to MPFR. See Michal's message. It isn't
particularly fast
but it works. You could improve/suggest improvements there, if you are
interested.
Why does the C version work, but the Haskell version flake out?
I'm more or less guessing here, but it might have something to do with mpfr
calling __gmp_allocate_func in init2.c which is called inside
mpfr_init_set_si, coupled
with what Judah Jacobson said. This is the only possible problem I can
think of because
when using custom memory interface and allocating with malloc all the
problems seem to disappear.
If you substitute your mpfr_set_signed_int for the one below, the noworks
should become works.
mpfr_ptr mpf_set_signed_int(int x)
{
mpfr_ptr result = mpf_new_mpfr();
mp_limb_t * limb = malloc(mpfr_custom_get_size(mpfr_get_default_prec()));
mpfr_custom_init(limb, mpfr_get_default_prec());
mpfr_custom_init_set(result, MPFR_NAN_KIND, 0, mpfr_get_default_prec(),
limb);
if (result == NULL)
return NULL;
mpfr_set_si(result, x, GMP_RNDN);
return result;
}
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