ilyakooo0/urbit
1
0
Fork 0
mirror of https://github.com/ilyakooo0/urbit.git synced 2024-12-14 17:41:33 +03:00
Code Issues Packages Projects Releases Wiki Activity

Optimize: u3a_malt takes care of trailing zeros.

Browse Source
This commit is contained in:
Benjamin Summers 2019-12-10 19:32:43 -08:00 committed by Logan Allen
parent f391a26334
commit 290bf55c45
1 changed files with 10 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
pkg/urbit/jets/c/repn.c
View File

@ -15,41 +15,11 @@
(x==0) ? 0 : \
1 + ((x - 1) / y);
/*
TODO Don't do the double flop.
*/
u3_noun u3qc_repn(u3_atom bits, u3_noun blox) {
if ( !_(u3a_is_cat(bits) || bits==0 || bits>31) ) {
return u3m_bail(c3__fail);
}
blox = u3kb_flop(blox);
//
// We need to enforce the invariant that the result does not contain
// leading (? TODO). Since each input block must be smaller than
// a word, simply stripping off leading zero blocks is enough to
// ensure this.
//
// We also verify that each input block is a direct atom.
//
while (1) {
if (blox == 0) {
return 0;
}
u3_noun blok_n = u3h(blox);
if (!_(u3a_is_cat(blok_n)))
return u3m_bail(c3__fail);
if (blok_n != 0) break;
blox = u3t(blox);
}
blox = u3kb_flop(blox);
//
// Calculate input and output size.
//
@ -77,16 +47,15 @@ u3_noun u3qc_repn(u3_atom bits, u3_noun blox) {
// once full.
//
// acc register
// idx where the register will be flushed to
// use number of register bits filled (used)
// cur next buffer word to flush into.
//
c3_w acc=0, idx=0, use=0;
c3_w acc=0, use=0, *cur=buf;
void flush() {
buf[idx++] = acc;
acc = 0;
use = 0;
*cur++ = acc;
acc = use = 0;
}
c3_w slice(c3_w sz, c3_w off, c3_w val) {
@ -94,9 +63,14 @@ u3_noun u3qc_repn(u3_atom bits, u3_noun blox) {
}
for (c3_w i=0; i<num_blox; i++) {
c3_w blok = u3a_h(blox);
u3_noun blok_n = u3h(blox);
blox = u3t(blox);
if (!_(u3a_is_cat(blok_n)))
return u3m_bail(c3__fail);
c3_w blok = blok_n;
for (c3_w rem_in_blok=bits; rem_in_blok;) {
c3_w rem_in_acc = 32 - use;
if (rem_in_blok == rem_in_acc) { // EQ
@ -114,7 +88,6 @@ u3_noun u3qc_repn(u3_atom bits, u3_noun blox) {
flush();
}
}
}
//