urbit/j/a/dec.c
2014-11-17 13:56:51 -08:00

49 lines
708 B
C

/* j/1/dec.c
**
** This file is in the public domain.
*/
#include "all.h"
/* functions
*/
u3_noun
u3qa_inc(u3_atom a)
{
return u3i_vint(u3k(a));
}
u3_noun
u3qa_dec(u3_atom a)
{
if ( 0 == a ) {
return u3m_error("decrement-underflow");
}
else {
if ( _(u3a_is_cat(a)) ) {
return a - 1;
}
else {
mpz_t a_mp;
u3r_mp(a_mp, a);
mpz_sub_ui(a_mp, a_mp, 1);
return u3i_mp(a_mp);
}
}
}
u3_noun
u3wa_dec(u3_noun cor)
{
u3_noun a;
if ( (u3_none == (a = u3r_at(u3x_sam, cor))) ||
(c3n == u3ud(a)) )
{
return u3m_bail(c3__exit);
} else {
return u3qa_dec(a);
}
}