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wcsmbs: optimize wcsncat

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This patch rewrites wcsncat using wcslen, wcsnlen, and wmemcpy.  This is
similar to the optimization done on strncat by 3eb38795db and e80514b5a8.

Checked on x86_64-linux-gnu.

	* wcsmbs/wcsncat.c (wcsncat): Rewrite using wcslen, wcsnlen, and
	wmemcpy.
This commit is contained in:
Adhemerval Zanella 2019-02-05 18:43:18 -02:00
parent 4d8015639a
commit ddf21ec79f
2 changed files with 10 additions and 46 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2019-02-27 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* wcsmbs/wcsncat.c (wcsncat): Rewrite using wcslen, wcsnlen, and
wmemcpy.
* wcsmbs/wcscpy.c (__wcpcpy): Rewrite using wcslen and wmemcpy.
* include/wchar.h (__wcscpy): New prototype.

53
wcsmbs/wcsncat.c
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@ -26,54 +26,15 @@
wchar_t *
WCSNCAT (wchar_t *dest, const wchar_t *src, size_t n)
{
wchar_t c;
wchar_t * const s = dest;
wchar_t *ret = dest;
/* Find the end of DEST. */
do
c = *dest++;
while (c != L'\0');
/* Find the end of dest. */
dest += __wcslen (dest);
/* Make DEST point before next character, so we can increment
it while memory is read (wins on pipelined cpus). */
dest -= 2;
size_t ds = __wcsnlen (src, n);
if (n >= 4)
{
size_t n4 = n >> 2;
do
{
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
} while (--n4 > 0);
n &= 3;
}
dest[ds] = L'\0';
__wmemcpy (dest, src, ds);
while (n > 0)
{
c = *src++;
*++dest = c;
if (c == L'\0')
return s;
n--;
}
if (c != L'\0')
*++dest = L'\0';
return s;
return ret;
}