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Re: [PATCH 2/7] wcsmbs: optimize wcpncpy
If no one opposes it, I will commit this shortly.
On 06/02/2019 12:58, Adhemerval Zanella wrote:
> 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
>