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urbit/j/3/can.c
2014-11-04 17:18:47 -08:00

86 lines
1.8 KiB
C

/* j/3/can.c
**
** This file is in the public domain.
*/
#include "all.h"
/* functions
*/
u3_noun
u3_cqc_can(u3_atom a,
u3_noun b)
{
if ( !_(u3_ca_is_cat(a)) || (a >= 32) ) {
return u3_cm_bail(c3__fail);
}
else {
c3_g a_g = a;
c3_w tot_w = 0;
c3_w* sal_w;
/* Measure and validate the slab required.
*/
{
u3_noun cab = b;
while ( 1 ) {
u3_noun i_cab, pi_cab, qi_cab;
if ( 0 == cab ) {
break;
}
if ( c3n == u3du(cab) ) return u3_cm_bail(c3__fail);
i_cab = u3h(cab);
if ( c3n == u3du(i_cab) ) return u3_cm_bail(c3__fail);
pi_cab = u3h(i_cab);
qi_cab = u3t(i_cab);
if ( c3n == u3_ca_is_cat(pi_cab) ) return u3_cm_bail(c3__fail);
if ( c3n == u3ud(qi_cab) ) return u3_cm_bail(c3__fail);
if ( (tot_w + pi_cab) < tot_w ) return u3_cm_bail(c3__fail);
tot_w += pi_cab;
cab = u3t(cab);
}
if ( 0 == tot_w ) {
return 0;
}
if ( 0 == (sal_w = u3_ca_slaq(a_g, tot_w)) ) {
return u3_cm_bail(c3__fail);
}
}
/* Chop the list atoms in.
*/
{
u3_noun cab = b;
c3_w pos_w = 0;
while ( 0 != cab ) {
u3_noun i_cab = u3h(cab);
u3_atom pi_cab = u3h(i_cab);
u3_atom qi_cab = u3t(i_cab);
u3_cr_chop(a_g, 0, pi_cab, pos_w, sal_w, qi_cab);
pos_w += pi_cab;
cab = u3t(cab);
}
}
return u3_ca_malt(sal_w);
}
}
u3_noun
u3_cwc_can(u3_noun cor)
{
u3_noun a, b;
if ( (c3n == u3_cr_mean(cor, u3_cv_sam_2, &a, u3_cv_sam_3, &b, 0)) ||
(c3n == u3ud(a)) )
{
return u3_cm_bail(c3__fail);
} else {
return u3_cqc_can(a, b);
}
}