Add a couple of mips-specific string funcs.

Port the generic optimized string funcs from glibc, with some tweaks
  to cut their size a little.  The main change is making memmove
  call memcpy for forward copying to trim redundant code.
Make use of both the generic and arch-specific speed-optimized string
  funcs configurable.  Arch-specific take precedence over generic,
  and generic takes precedence over basic size-optimized uClibc funcs.

1 files changed, 75 insertions, 0 deletions

diff --git a/libc/string/generic/pagecopy.h b/libc/string/generic/pagecopy.h
new file mode 100644
index 000000000..5a0ada1fa
--- /dev/null
+++ b/libc/string/generic/pagecopy.h
@@ -0,0 +1,75 @@
+/* Macros for copying by pages; used in memcpy, memmove.  Generic macros.
+   Copyright (C) 1995, 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.  */
+
+/* This file defines the macro:
+
+   PAGE_COPY_FWD_MAYBE (dstp, srcp, nbytes_left, nbytes)
+
+   which is invoked like WORD_COPY_FWD et al.  The pointers should be at
+   least word aligned.  This will check if virtual copying by pages can and
+   should be done and do it if so.
+
+   System-specific pagecopy.h files should define these macros and then
+   #include this file:
+
+   PAGE_COPY_THRESHOLD
+   -- Minimum size for which virtual copying by pages is worthwhile.
+
+   PAGE_SIZE
+   -- Size of a page.
+
+   PAGE_COPY_FWD (dstp, srcp, nbytes_left, nbytes)
+   -- Macro to perform the virtual copy operation.
+   The pointers will be aligned to PAGE_SIZE bytes.
+*/
+
+
+#if PAGE_COPY_THRESHOLD
+
+#include <assert.h>
+
+#define PAGE_COPY_FWD_MAYBE(dstp, srcp, nbytes_left, nbytes)		      \
+  do									      \
+    {									      \
+      if ((nbytes) >= PAGE_COPY_THRESHOLD &&				      \
+	  PAGE_OFFSET ((dstp) - (srcp)) == 0) 				      \
+	{								      \
+	  /* The amount to copy is past the threshold for copying	      \
+	     pages virtually with kernel VM operations, and the		      \
+	     source and destination addresses have the same alignment.  */    \
+	  size_t nbytes_before = PAGE_OFFSET (-(dstp));			      \
+	  if (nbytes_before != 0)					      \
+	    {								      \
+	      /* First copy the words before the first page boundary.  */     \
+	      WORD_COPY_FWD (dstp, srcp, nbytes_left, nbytes_before);	      \
+	      assert (nbytes_left == 0);				      \
+	      nbytes -= nbytes_before;					      \
+	    }								      \
+	  PAGE_COPY_FWD (dstp, srcp, nbytes_left, nbytes);		      \
+	}								      \
+    } while (0)
+
+/* The page size is always a power of two, so we can avoid modulo division.  */
+#define PAGE_OFFSET(n)	((n) & (PAGE_SIZE - 1))
+
+#else
+
+#define PAGE_COPY_FWD_MAYBE(dstp, srcp, nbytes_left, nbytes) /* nada */
+
+#endif