1 files changed, 115 insertions, 0 deletions
diff --git a/newlib/libc/string/strncat.c b/newlib/libc/string/strncat.c
new file mode 100644
index 00000000000..57ca068eb1a
--- /dev/null
+++ b/newlib/libc/string/strncat.c
@@ -0,0 +1,115 @@
+/*
+FUNCTION
+	<<strncat>>---concatenate strings
+
+INDEX
+	strncat
+
+ANSI_SYNOPSIS
+	#include <string.h>
+	char *strncat(char *<[dst]>, const char *<[src]>, size_t <[length]>);
+
+TRAD_SYNOPSIS
+	#include <string.h>
+	char *strncat(<[dst]>, <[src]>, <[length]>)
+	char *<[dst]>;
+	char *<[src]>;
+	size_t <[length]>;
+
+DESCRIPTION
+	<<strncat>> appends not more than <[length]> characters from
+	the string pointed to by <[src]> (including the	terminating
+	null character) to the end of the string pointed to by
+	<[dst]>.  The initial character of <[src]> overwrites the null
+	character at the end of <[dst]>.  A terminating null character
+	is always appended to the result
+
+WARNINGS
+	Note that a null is always appended, so that if the copy is
+	limited by the <[length]> argument, the number of characters
+	appended to <[dst]> is <<n + 1>>.
+	
+
+RETURNS
+	This function returns the initial value of <[dst]>
+
+PORTABILITY
+<<strncat>> is ANSI C.
+
+<<strncat>> requires no supporting OS subroutines.
+
+QUICKREF
+	strncat ansi pure
+*/
+
+#include <string.h>
+#include <limits.h>
+
+/* Nonzero if X is aligned on a "long" boundary.  */
+#define ALIGNED(X) \
+  (((long)X & (sizeof (long) - 1)) == 0)
+
+#if LONG_MAX == 2147483647L
+#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
+#else
+#if LONG_MAX == 9223372036854775807L
+/* Nonzero if X (a long int) contains a NULL byte. */
+#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
+#else
+#error long int is not a 32bit or 64bit type.
+#endif
+#endif
+
+#ifndef DETECTNULL
+#error long int is not a 32bit or 64bit byte
+#endif
+
+char *
+_DEFUN (strncat, (s1, s2, n),
+	char *s1 _AND
+	_CONST char *s2 _AND
+	size_t n)
+{
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+  char *s = s1;
+
+  while (*s1)
+    s1++;
+  while (n-- != 0 && (*s1++ = *s2++))
+    {
+      if (n == 0)
+	*s1 = '\0';
+    }
+
+  return s;
+#else
+  char *s = s1;
+
+  /* Skip over the data in s1 as quickly as possible.  */
+  if (ALIGNED (s1))
+    {
+      unsigned long *aligned_s1 = (unsigned long *)s1;
+      while (!DETECTNULL (*aligned_s1))
+	aligned_s1++;
+
+      s1 = (char *)aligned_s1;
+    }
+
+  while (*s1)
+    s1++;
+
+  /* s1 now points to the its trailing null character, now copy
+     up to N bytes from S2 into S1 stopping if a NULL is encountered
+     in S2.
+
+     It is not safe to use strncpy here since it copies EXACTLY N
+     characters, NULL padding if necessary.  */
+  while (n-- != 0 && (*s1++ = *s2++))
+    {
+      if (n == 0)
+	*s1 = '\0';
+    }
+	
+  return s;
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}