urbit/jets/c/muk.c
2019-01-08 22:44:56 -05:00

65 lines
1.3 KiB
C

/* j/c/muk.c
**
*/
#include "all.h"
#include <murmur3.h>
/* functions
*/
u3_noun
u3qc_muk(u3_atom seed,
u3_atom len,
u3_atom key)
{
c3_w seed_w;
c3_w len_w;
c3_y *key_y;
c3_w out_w;
c3_assert( u3r_met(5, seed) <= 1 );
c3_assert( u3r_met(0, len) <= 31 );
c3_assert( u3r_met(3, key) <= len );
seed_w = u3r_word(0, seed);
len_w = u3r_word(0, len);
// can't u3a_calloc 0 bytes
//
if ( 0 == len_w ) {
key_y = 0;
}
else {
key_y = u3a_calloc(sizeof(c3_y), len_w);
}
// Efficiency: unnecessary copy.
//
// We could calculate the hash directly against
// the atom internals, a la u3r_mug
//
u3r_bytes(0, len_w, key_y, key);
MurmurHash3_x86_32(key_y, len_w, seed_w, &out_w);
u3a_free(key_y);
return u3i_words(1, &out_w);
}
u3_noun
u3wc_muk(u3_noun cor)
{
u3_noun seed, len, key;
if ( (c3n == u3r_mean(cor, u3x_sam_2, &seed,
u3x_sam_6, &len,
u3x_sam_7, &key, 0)) ||
(c3n == u3ud(seed)) ||
(c3n == u3ud(len)) ||
(c3n == u3ud(key)) )
{
return u3m_bail(c3__exit);
} else {
return u3qc_muk(seed, len, key);
}
}