[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 6

The attached patches provides part 6 of an architecture implementation for the
Tensilica Xtensa CPU series.

Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 82 insertions, 0 deletions

diff --git a/include/asm-xtensa/byteorder.h b/include/asm-xtensa/byteorder.h
new file mode 100644
index 00000000000..0b1552569aa
--- /dev/null
+++ b/include/asm-xtensa/byteorder.h
@@ -0,0 +1,82 @@
+/*
+ * include/asm-xtensa/byteorder.h
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2001 - 2005 Tensilica Inc.
+ */
+
+#ifndef _XTENSA_BYTEORDER_H
+#define _XTENSA_BYTEORDER_H
+
+#include <asm/processor.h>
+#include <asm/types.h>
+
+static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
+{
+    __u32 res;
+    /* instruction sequence from Xtensa ISA release 2/2000 */
+    __asm__("ssai     8           \n\t"
+	    "srli     %0, %1, 16  \n\t"
+	    "src      %0, %0, %1  \n\t"
+	    "src      %0, %0, %0  \n\t"
+	    "src      %0, %1, %0  \n"
+	    : "=&a" (res)
+	    : "a" (x)
+	    );
+    return res;
+}
+
+static __inline__ __const__ __u16 ___arch__swab16(__u16 x)
+{
+    /* Given that 'short' values are signed (i.e., can be negative),
+     * we cannot assume that the upper 16-bits of the register are
+     * zero.  We are careful to mask values after shifting.
+     */
+
+    /* There exists an anomaly between xt-gcc and xt-xcc.  xt-gcc
+     * inserts an extui instruction after putting this function inline
+     * to ensure that it uses only the least-significant 16 bits of
+     * the result.  xt-xcc doesn't use an extui, but assumes the
+     * __asm__ macro follows convention that the upper 16 bits of an
+     * 'unsigned short' result are still zero.  This macro doesn't
+     * follow convention; indeed, it leaves garbage in the upport 16
+     * bits of the register.
+
+     * Declaring the temporary variables 'res' and 'tmp' to be 32-bit
+     * types while the return type of the function is a 16-bit type
+     * forces both compilers to insert exactly one extui instruction
+     * (or equivalent) to mask off the upper 16 bits. */
+
+    __u32 res;
+    __u32 tmp;
+
+    __asm__("extui    %1, %2, 8, 8\n\t"
+	    "slli     %0, %2, 8   \n\t"
+	    "or       %0, %0, %1  \n"
+	    : "=&a" (res), "=&a" (tmp)
+	    : "a" (x)
+	    );
+
+    return res;
+}
+
+#define __arch__swab32(x) ___arch__swab32(x)
+#define __arch__swab16(x) ___arch__swab16(x)
+
+#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
+#  define __BYTEORDER_HAS_U64__
+#  define __SWAB_64_THRU_32__
+#endif
+
+#ifdef __XTENSA_EL__
+# include <linux/byteorder/little_endian.h>
+#elif defined(__XTENSA_EB__)
+# include <linux/byteorder/big_endian.h>
+#else
+# error processor byte order undefined!
+#endif
+
+#endif /* __ASM_XTENSA_BYTEORDER_H */