summaryrefslogtreecommitdiff
path: root/libc/string/generic/strncat.c
diff options
context:
space:
mode:
Diffstat (limited to 'libc/string/generic/strncat.c')
-rw-r--r--libc/string/generic/strncat.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/libc/string/generic/strncat.c b/libc/string/generic/strncat.c
new file mode 100644
index 000000000..a3d283bf7
--- /dev/null
+++ b/libc/string/generic/strncat.c
@@ -0,0 +1,81 @@
+/* Copyright (C) 1991, 1997 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 strncat
+
+char *
+strncat (s1, s2, n)
+ char *s1;
+ const char *s2;
+ size_t n;
+{
+ reg_char c;
+ char *s = s1;
+
+ /* Find the end of S1. */
+ do
+ c = *s1++;
+ while (c != '\0');
+
+ /* Make S1 point before next character, so we can increment
+ it while memory is read (wins on pipelined cpus). */
+ s1 -= 2;
+
+ if (n >= 4)
+ {
+ size_t n4 = n >> 2;
+ do
+ {
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ return s;
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ return s;
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ return s;
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ return s;
+ } while (--n4 > 0);
+ n &= 3;
+ }
+
+ while (n > 0)
+ {
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ return s;
+ n--;
+ }
+
+ if (c != '\0')
+ *++s1 = '\0';
+
+ return s;
+}