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Merge branch 'muk-alloc-less' (#1722)

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* muk-alloc-less:
  u3: rewrites +muk jet to skip heap allocations where possible

Signed-off-by: Jared Tobin <jared@tlon.io>
This commit is contained in:
Jared Tobin 2019-09-12 06:48:46 -02:30
commit 5cdbee9418
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GPG Key ID: 0E4647D58F8A69E4
1 changed files with 61 additions and 43 deletions
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104
pkg/urbit/jets/c/muk.c
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@ -6,59 +6,77 @@
/* functions
*/
u3_noun
u3qc_muk(u3_atom seed,
u3_atom len,
u3_atom key)
u3_noun
u3qc_muk(u3_atom seed,
u3_atom len,
u3_atom key)
{
c3_w key_w = u3r_met(3, key);
// XX revisit
//
// the first two conditions are explicitly asserted in +muk;
// the third is implicit in the pad subtraction.
//
// the first assertion is semantically required for murmur32,
// the latter two are particular to our hoon implementation.
//
// +muk (via +mug) is routinely "called" on samples that
// violate these assertions.
// are all three necessary for the rest of +muk to be correct?
//
if ( (u3r_met(5, seed) > 1) ||
(u3r_met(0, len) > 31) ||
(key_w > len) )
{
c3_w seed_w;
c3_w len_w;
c3_y *key_y;
c3_w out_w;
return u3m_bail(c3__exit);
}
else {
c3_w seed_w = u3r_word(0, seed);
c3_w len_w = u3r_word(0, len);
c3_o loc_o = c3n;
c3_y* key_y = 0;
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 we're hashing more bytes than we have, allocate and copy
// to ensure trailing null bytes
//
if ( 0 == len_w ) {
key_y = 0;
}
else {
if ( len_w > key_w ) {
loc_o = c3y;
key_y = u3a_calloc(sizeof(c3_y), len_w);
u3r_bytes(0, len_w, key_y, key);
}
else if ( len_w > 0 ) {
key_y = ( c3y == u3a_is_cat(key) )
? (c3_y*)&key
: (c3_y*)((u3a_atom*)u3a_to_ptr(key))->buf_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);
if ( c3y == loc_o ) {
u3a_free(key_y);
}
return u3i_words(1, &out_w);
}
}
u3_noun
u3wc_muk(u3_noun cor)
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)) )
{
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);
}
return u3m_bail(c3__exit);
}
else {
return u3qc_muk(seed, len, key);
}
}