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| author | Felipe Oliveira Carvalho <felipekde@gmail.com> | 2014-04-19 13:12:04 -0300 |
|---|---|---|
| committer | Thiago de Arruda <tpadilha84@gmail.com> | 2014-04-24 10:32:47 -0300 |
| commit | db23cb05d1d40487007b3c93dd54fab290fd02b7 (patch) | |
| tree | e43f5a0cc4314e239015de512b636c93a005dc83 /src/hashtab.c | |
| parent | 9a5b3eee5f73594f5e3f71411f6a7d4fe2b9da55 (diff) | |
| download | rneovim-db23cb05d1d40487007b3c93dd54fab290fd02b7.tar.gz rneovim-db23cb05d1d40487007b3c93dd54fab290fd02b7.tar.bz2 rneovim-db23cb05d1d40487007b3c93dd54fab290fd02b7.zip | |
Use /2 and 2* instead of >>1 and <<1 which are tricky with signed types
Today's compilers generate shift instructions to perform division and
multiplications by powers of 2 [1]. `(x >> 1)` looks straightforward enough, but
if x is signed the code will fail when x < 0. The compiler knows better: use
`x / 2`.
That's why we have code like this:
(long)((long_u)Rows >> 1))
instead of the cleaner version that generates the same or better machine code:
Rows / 2
[1] http://goo.gl/J4WpG7
Diffstat (limited to 'src/hashtab.c')
| -rw-r--r-- | src/hashtab.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/hashtab.c b/src/hashtab.c index b84b56278f..a43180d6cb 100644 --- a/src/hashtab.c +++ b/src/hashtab.c @@ -141,7 +141,7 @@ hashitem_T* hash_lookup(hashtab_T *ht, char_u *key, hash_T hash) // count a "miss" for hashtab lookup hash_count_perturb++; #endif // ifdef HT_DEBUG - idx = (unsigned)((idx << 2U) + idx + perturb + 1U); + idx = 5 * idx + perturb + 1; hi = &ht->ht_array[idx & ht->ht_mask]; if (hi->hi_key == NULL) { @@ -378,7 +378,7 @@ static int hash_may_resize(hashtab_T *ht, int minitems) newitem = &newarray[newi]; if (newitem->hi_key != NULL) { for (perturb = olditem->hi_hash;; perturb >>= PERTURB_SHIFT) { - newi = (unsigned)((newi << 2U) + newi + perturb + 1U); + newi = 5 * newi + perturb + 1; newitem = &newarray[newi & newmask]; if (newitem->hi_key == NULL) { break; |