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[PATCH 2/7] wcsmbs: optimize wcpncpy
This patch rewrites wcpncpy using wcslen, wmemcpy, and wmemset. This is
similar to the optimization done on stpncpy by 48497aba8e.
Checked on x86_64-linux-gnu.
* wcsmbs/wcpncpy.c (__wcpcpy): Rewrite using wcslen, wmemcpy, and
wmemset.
---
wcsmbs/wcpncpy.c | 58 +++++-------------------------------------------
1 file changed, 6 insertions(+), 52 deletions(-)
diff --git a/wcsmbs/wcpncpy.c b/wcsmbs/wcpncpy.c
index 7568f3b11c..7147affdd5 100644
--- a/wcsmbs/wcpncpy.c
+++ b/wcsmbs/wcpncpy.c
@@ -17,6 +17,7 @@
<http://www.gnu.org/licenses/>. */
#include <wchar.h>
+#include <string.h>
#ifdef WCPNCPY
# define __wcpncpy WCPNCPY
@@ -27,59 +28,12 @@
wchar_t *
__wcpncpy (wchar_t *dest, const wchar_t *src, size_t n)
{
- wint_t c;
- wchar_t *const s = dest;
-
- if (n >= 4)
- {
- size_t n4 = n >> 2;
-
- for (;;)
- {
- c = *src++;
- *dest++ = c;
- if (c == L'\0')
- break;
- c = *src++;
- *dest++ = c;
- if (c == L'\0')
- break;
- c = *src++;
- *dest++ = c;
- if (c == L'\0')
- break;
- c = *src++;
- *dest++ = c;
- if (c == L'\0')
- break;
- if (--n4 == 0)
- goto last_chars;
- }
- n -= dest - s;
- goto zero_fill;
- }
-
- last_chars:
- n &= 3;
- if (n == 0)
+ size_t size = __wcsnlen (src, n);
+ __wmemcpy (dest, src, size);
+ dest += size;
+ if (size == n)
return dest;
-
- for (;;)
- {
- c = *src++;
- --n;
- *dest++ = c;
- if (c == L'\0')
- break;
- if (n == 0)
- return dest;
- }
-
- zero_fill:
- while (n-- > 0)
- dest[n] = L'\0';
-
- return dest - 1;
+ return wmemset (dest, L'\0', (n - size));
}
#ifndef WCPNCPY
--
2.17.1