urbit/j/b/roll.c
2015-02-10 15:13:17 -08:00

47 lines
862 B
C

/* j/2/roll.c
**
*/
#include "all.h"
/* functions
*/
u3_noun
u3qb_roll(u3_noun a,
u3_noun b)
{
if ( 0 == a ) {
return u3k(u3r_at(u3x_sam_3, b));
}
else if ( c3n == u3du(a) ) {
return u3m_bail(c3__exit);
}
else {
u3_noun gim = u3k(u3h(a));
u3_noun zor = u3k(u3r_at(u3x_sam_3, b));
u3_noun daz = u3n_slam_on(u3k(b), u3nc(gim, zor));
u3_noun vel = u3i_molt(u3k(b), u3x_sam_3, daz, 0);
if ( u3_none == vel ) {
return u3m_bail(c3__exit);
} else {
u3_noun hox = u3qb_roll(u3t(a), vel);
u3z(vel);
return hox;
}
}
}
u3_noun
u3wb_roll(u3_noun cor)
{
u3_noun a, b;
if ( c3n == u3r_mean(cor, u3x_sam_2, &a, u3x_sam_3, &b, 0) ) {
return u3m_bail(c3__exit);
} else {
return u3qb_roll(a, b);
}
}