Introducing memcchr(3).

It seems two of the file system drivers we have in the tree, namely ufs
and ext3, use a function called `skpc()'. The meaning of this function
does not seem to be documented in FreeBSD, but it turns out one needs to
be a VAX programmer to understand what it does.

SPKC is an instruction on the VAX that does the opposite of memchr(). It
searches for the non-equal character. Add a new function called
memcchr() to the tree that has the following advantages over skpc():

- It has a name that makes more sense than skpc(). Just like strcspn()
  matches the complement of strspn(), memcchr() is the complement of
  memchr().

- It is faster than skpc(). Similar to our strlen() in libc, it compares
  entire words, instead of single bytes. It seems that for this routine
  this yields a sixfold performance increase on amd64.

- It has a man page.

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/sys/libkern.h b/sys/sys/libkern.h
index aa53fb7..0e525de 100644
--- a/sys/sys/libkern.h
+++ b/sys/sys/libkern.h
@@ -92,6 +92,7 @@ int	 flsl(long);
 int	 fnmatch(const char *, const char *, int);
 int	 locc(int, char *, u_int);
 void	*memchr(const void *s, int c, size_t n);
+void	*memcchr(const void *s, int c, size_t n);
 int	 memcmp(const void *b1, const void *b2, size_t len);
 void	 qsort(void *base, size_t nmemb, size_t size,
 	    int (*compar)(const void *, const void *));