From 457208b1e9498c1238b7af4387529388df0414c1 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Tue, 5 Feb 2019 18:55:59 -0200 Subject: [PATCH] wcsmbs: optimize wcsnlen This patch rewrites wcsnlen using wmemchr. The generic wmemchr already uses the strategy (loop unrolling and tail handling) and by using it it allows architectures that have optimized wmemchr (s390 and x86_64) to optimize wcsnlen as well. Checked on x86_64-linux-gnu. * wcsmbs/wcsnlen.c (__wcsnlen): Rewrite using wmemchr. --- ChangeLog | 2 ++ wcsmbs/wcsnlen.c | 22 ++++------------------ 2 files changed, 6 insertions(+), 18 deletions(-) diff --git a/ChangeLog b/ChangeLog index 97e70aa..9ab66cf 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,7 @@ 2019-02-27 Adhemerval Zanella + * wcsmbs/wcsnlen.c (__wcsnlen): Rewrite using wmemchr. + * wcsmbs/wcsncpy.c (__wcsncpy): Rewrite using wcsnlen, wmemset, and wmemcpy. diff --git a/wcsmbs/wcsnlen.c b/wcsmbs/wcsnlen.c index f3d5fc1..d38c7e4 100644 --- a/wcsmbs/wcsnlen.c +++ b/wcsmbs/wcsnlen.c @@ -26,24 +26,10 @@ size_t __wcsnlen (const wchar_t *s, size_t maxlen) { - size_t len = 0; - - while (maxlen > 0 && s[len] != L'\0') - { - ++len; - if (--maxlen == 0 || s[len] == L'\0') - return len; - ++len; - if (--maxlen == 0 || s[len] == L'\0') - return len; - ++len; - if (--maxlen == 0 || s[len] == L'\0') - return len; - ++len; - --maxlen; - } - - return len; + const wchar_t *ret = __wmemchr (s, L'\0', maxlen); + if (ret) + maxlen = ret - s; + return maxlen; } #ifndef WCSNLEN weak_alias (__wcsnlen, wcsnlen) -- 2.7.4