1 files changed, 122 insertions, 0 deletions
diff --git a/newlib/libc/string/strncmp.c b/newlib/libc/string/strncmp.c
new file mode 100644
index 00000000000..9801b7d9248
--- /dev/null
+++ b/newlib/libc/string/strncmp.c
@@ -0,0 +1,122 @@
+/*
+FUNCTION
+	<<strncmp>>---character string compare
+	
+INDEX
+	strncmp
+
+ANSI_SYNOPSIS
+	#include <string.h>
+	int strncmp(const char *<[a]>, const char * <[b]>, size_t <[length]>);
+
+TRAD_SYNOPSIS
+	#include <string.h>
+	int strncmp(<[a]>, <[b]>, <[length]>)
+	char *<[a]>;
+	char *<[b]>;
+	size_t <[length]>
+
+DESCRIPTION
+	<<strncmp>> compares up to <[length]> characters
+	from the string at <[a]> to the string at <[b]>.
+
+RETURNS
+	If <<*<[a]>>> sorts lexicographically after <<*<[b]>>>,
+	<<strncmp>> returns a number greater than zero.  If the two
+	strings are equivalent, <<strncmp>> returns zero.  If <<*<[a]>>>
+	sorts lexicographically before <<*<[b]>>>, <<strncmp>> returns a
+	number less than zero.
+
+PORTABILITY
+<<strncmp>> is ANSI C.
+
+<<strncmp>> requires no supporting OS subroutines.
+
+QUICKREF
+	strncmp ansi pure
+*/
+
+#include <string.h>
+#include <limits.h>
+
+/* Nonzero if either X or Y is not aligned on a "long" boundary.  */
+#define UNALIGNED(X, Y) \
+  (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
+
+/* DETECTNULL returns nonzero if (long)X contains a NULL byte. */
+#if LONG_MAX == 2147483647L
+#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
+#else
+#if LONG_MAX == 9223372036854775807L
+#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
+
+int 
+_DEFUN (strncmp, (s1, s2, n),
+	_CONST char *s1 _AND
+	_CONST char *s2 _AND
+	size_t n)
+{
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+  if (n == 0)
+    return 0;
+
+  while (n-- != 0 && *s1 == *s2)
+    {
+      if (n == 0 || *s1 == '\0')
+	break;
+      s1++;
+      s2++;
+    }
+
+  return (*(unsigned char *) s1) - (*(unsigned char *) s2);
+#else
+  unsigned long *a1;
+  unsigned long *a2;
+
+  if (n == 0)
+    return 0;
+
+  /* If s1 or s2 are unaligned, then compare bytes. */
+  if (!UNALIGNED (s1, s2))
+    {
+      /* If s1 and s2 are word-aligned, compare them a word at a time. */
+      a1 = (unsigned long*)s1;
+      a2 = (unsigned long*)s2;
+      while (n >= sizeof (long) && *a1 == *a2)
+        {
+          n -= sizeof (long);
+
+          /* If we've run out of bytes or hit a null, return zero
+	     since we already know *a1 == *a2.  */
+          if (n == 0 || DETECTNULL (*a1))
+	    return 0;
+
+          a1++;
+          a2++;
+        }
+
+      /* A difference was detected in last few bytes of s1, so search bytewise */
+      s1 = (char*)a1;
+      s2 = (char*)a2;
+    }
+
+  while (n-- > 0 && *s1 == *s2)
+    {
+      /* If we've run out of bytes or hit a null, return zero
+	 since we already know *s1 == *s2.  */
+      if (n == 0 || *s1 == '\0')
+	return 0;
+      s1++;
+      s2++;
+    }
+  return (*(unsigned char *) s1) - (*(unsigned char *) s2);
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}