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/// @file

#include "jets/k.h"
#include "jets/q.h"
#include "jets/w.h"

#include "noun.h"

u3_noun
u3qa_sub(u3_atom a,
         u3_atom b)
{
  if ( _(u3a_is_cat(a)) && _(u3a_is_cat(b)) ) {
    if ( a < b ) {
      return u3m_error("subtract-underflow");
    }
    else {
      return (a - b);
    }
  }
  else if ( 0 == b ) {
    return u3k(a);
  }
  else {
    mpz_t a_mp, b_mp;

    u3r_mp(a_mp, a);
    u3r_mp(b_mp, b);

    if ( mpz_cmp(a_mp, b_mp) < 0 ) {
      mpz_clear(a_mp);
      mpz_clear(b_mp);

      return u3m_error("subtract-underflow");
    }
    mpz_sub(a_mp, a_mp, b_mp);
    mpz_clear(b_mp);

    return u3i_mp(a_mp);
  }
}

u3_noun
u3wa_sub(u3_noun cor)
{
  u3_noun a, b;

  if ( (c3n == u3r_mean(cor, u3x_sam_2, &a, u3x_sam_3, &b, 0)) ||
       (c3n == u3ud(b)) ||
       (c3n == u3ud(a)) )
  {
    return u3m_bail(c3__fail);
  }
  else {
    return u3qa_sub(a, b);
  }
}

u3_noun
u3ka_sub(u3_noun a,
         u3_noun b)
{
  u3_noun c = u3qa_sub(a, b);

  u3z(a); u3z(b);
  return c;
}