arch/tile: support building big-endian kernel

The toolchain supports big-endian mode now, so add support for building
the kernel to run big-endian as well.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/lib/string-endian.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2011 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program 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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ *
+ * Provide a mask based on the pointer alignment that
+ * sets up non-zero bytes before the beginning of the string.
+ * The MASK expression works because shift counts are taken mod 64.
+ * Also, specify how to count "first" and "last" bits
+ * when the bits have been read as a word.
+ */
+
+#include <asm/byteorder.h>
+
+#ifdef __LITTLE_ENDIAN
+#define MASK(x) (__insn_shl(1ULL, (x << 3)) - 1)
+#define NULMASK(x) ((2ULL << x) - 1)
+#define CFZ(x) __insn_ctz(x)
+#define REVCZ(x) __insn_clz(x)
+#else
+#define MASK(x) (__insn_shl(-2LL, ((-x << 3) - 1)))
+#define NULMASK(x) (-2LL << (63 - x))
+#define CFZ(x) __insn_clz(x)
+#define REVCZ(x) __insn_ctz(x)
+#endif