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-rw-r--r--libc/string/generic/strncmp.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/libc/string/generic/strncmp.c b/libc/string/generic/strncmp.c
new file mode 100644
index 000000000..d9964a883
--- /dev/null
+++ b/libc/string/generic/strncmp.c
@@ -0,0 +1,72 @@
+/* Copyright (C) 1991, 1996, 1997, 2003 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <string.h>
+#include "memcopy.h"
+
+#undef strncmp
+
+/* Compare no more than N characters of S1 and S2,
+ returning less than, equal to or greater than zero
+ if S1 is lexicographically less than, equal to or
+ greater than S2. */
+int
+strncmp (s1, s2, n)
+ const char *s1;
+ const char *s2;
+ size_t n;
+{
+ unsigned reg_char c1 = '\0';
+ unsigned reg_char c2 = '\0';
+
+ if (n >= 4)
+ {
+ size_t n4 = n >> 2;
+ do
+ {
+ c1 = (unsigned char) *s1++;
+ c2 = (unsigned char) *s2++;
+ if (c1 == '\0' || c1 != c2)
+ return c1 - c2;
+ c1 = (unsigned char) *s1++;
+ c2 = (unsigned char) *s2++;
+ if (c1 == '\0' || c1 != c2)
+ return c1 - c2;
+ c1 = (unsigned char) *s1++;
+ c2 = (unsigned char) *s2++;
+ if (c1 == '\0' || c1 != c2)
+ return c1 - c2;
+ c1 = (unsigned char) *s1++;
+ c2 = (unsigned char) *s2++;
+ if (c1 == '\0' || c1 != c2)
+ return c1 - c2;
+ } while (--n4 > 0);
+ n &= 3;
+ }
+
+ while (n > 0)
+ {
+ c1 = (unsigned char) *s1++;
+ c2 = (unsigned char) *s2++;
+ if (c1 == '\0' || c1 != c2)
+ return c1 - c2;
+ n--;
+ }
+
+ return c1 - c2;
+}