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Optimize latin_tolower(). Marge from master: https://android-git.corp.google.com/g/#change,49214

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Change-Id: Ib1d7711aca533c21e5179b557a3ed806ac3fbdc6
This commit is contained in:
Ken Wakasa 2010-04-21 23:07:14 +09:00
parent 07cab72ce4
commit 6874267be0
1 changed files with 19 additions and 12 deletions
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31
native/src/char_utils.cpp
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@ -14,7 +14,7 @@
* limitations under the License.
*/
#include <stdlib.h>
#include <sys/types.h>
namespace latinime {
@ -882,18 +882,25 @@ static const struct LatinCapitalSmallPair SORTED_CHAR_MAP[] = {
{ 0xFF3A, 0xFF5A } // FULLWIDTH LATIN CAPITAL LETTER Z
};
static int compare_pair_capital(const void *a, const void *b) {
return (int)((struct LatinCapitalSmallPair*)a)->capital
- (int)((struct LatinCapitalSmallPair*)b)->capital;
}
unsigned short latin_tolower(unsigned short c0) {
const struct LatinCapitalSmallPair *p;
const struct LatinCapitalSmallPair *base = SORTED_CHAR_MAP;
int c = c0;
int lim, cmp;
const size_t nmemb = sizeof(SORTED_CHAR_MAP) / sizeof(SORTED_CHAR_MAP[0]);
unsigned short latin_tolower(unsigned short c) {
struct LatinCapitalSmallPair *p =
(struct LatinCapitalSmallPair *)bsearch(&c, SORTED_CHAR_MAP,
sizeof(SORTED_CHAR_MAP) / sizeof(SORTED_CHAR_MAP[0]),
sizeof(SORTED_CHAR_MAP[0]),
compare_pair_capital);
return p ? p->small : c;
// Binary search: Taken from bionic
for (lim = nmemb; lim != 0; lim >>= 1) {
p = base + (lim >> 1);
cmp = c - (int)p->capital;
if (cmp == 0)
return p->small;
if (cmp > 0) { /* key > p: move right */
base = p + 1;
lim--;
} /* else move left */
}
return c0;
}
} // namespace latinime