1 files changed, 136 insertions, 0 deletions

diff --git a/include/asm-mn10300/unaligned.h b/include/asm-mn10300/unaligned.h
new file mode 100644
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+++ b/include/asm-mn10300/unaligned.h
@@ -0,0 +1,136 @@
+/* MN10300 Unaligned memory access handling
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#ifndef _ASM_UNALIGNED_H
+#define _ASM_UNALIGNED_H
+
+#include <asm/types.h>
+
+#if 0
+extern int __bug_unaligned_x(void *ptr);
+
+/*
+ * What is the most efficient way of loading/storing an unaligned value?
+ *
+ * That is the subject of this file.  Efficiency here is defined as
+ * minimum code size with minimum register usage for the common cases.
+ * It is currently not believed that long longs are common, so we
+ * trade efficiency for the chars, shorts and longs against the long
+ * longs.
+ *
+ * Current stats with gcc 2.7.2.2 for these functions:
+ *
+ *      ptrsize get:    code    regs    put:    code    regs
+ *      1               1       1               1       2
+ *      2               3       2               3       2
+ *      4               7       3               7       3
+ *      8               20      6               16      6
+ *
+ * gcc 2.95.1 seems to code differently:
+ *
+ *      ptrsize get:    code    regs    put:    code    regs
+ *      1               1       1               1       2
+ *      2               3       2               3       2
+ *      4               7       4               7       4
+ *      8               19      8               15      6
+ *
+ * which may or may not be more efficient (depending upon whether
+ * you can afford the extra registers).  Hopefully the gcc 2.95
+ * is inteligent enough to decide if it is better to use the
+ * extra register, but evidence so far seems to suggest otherwise.
+ *
+ * Unfortunately, gcc is not able to optimise the high word
+ * out of long long >> 32, or the low word from long long << 32
+ */
+
+#define __get_unaligned_2(__p)                                  \
+        (__p[0] | __p[1] << 8)
+
+#define __get_unaligned_4(__p)                                  \
+        (__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
+
+#define get_unaligned(ptr)                                      \
+({                                                              \
+        unsigned int __v1, __v2;                                \
+        __typeof__(*(ptr)) __v;                                 \
+        __u8 *__p = (__u8 *)(ptr);                              \
+                                                                \
+        switch (sizeof(*(ptr))) {                               \
+        case 1: __v = *(ptr);                   break;          \
+        case 2: __v = __get_unaligned_2(__p);   break;          \
+        case 4: __v = __get_unaligned_4(__p);   break;          \
+        case 8:                                                 \
+                __v2 = __get_unaligned_4((__p+4));              \
+                __v1 = __get_unaligned_4(__p);                  \
+                __v = ((unsigned long long)__v2 << 32 | __v1);  \
+                break;                                          \
+        default: __v = __bug_unaligned_x(__p);  break;          \
+        }                                                       \
+        __v;                                                    \
+})
+
+
+static inline void __put_unaligned_2(__u32 __v, register __u8 *__p)
+{
+        *__p++ = __v;
+        *__p++ = __v >> 8;
+}
+
+static inline void __put_unaligned_4(__u32 __v, register __u8 *__p)
+{
+        __put_unaligned_2(__v >> 16, __p + 2);
+        __put_unaligned_2(__v, __p);
+}
+
+static inline void __put_unaligned_8(const unsigned long long __v, __u8 *__p)
+{
+        /*
+         * tradeoff: 8 bytes of stack for all unaligned puts (2
+         * instructions), or an extra register in the long long
+         * case - go for the extra register.
+         */
+        __put_unaligned_4(__v >> 32, __p + 4);
+        __put_unaligned_4(__v, __p);
+}
+
+/*
+ * Try to store an unaligned value as efficiently as possible.
+ */
+#define put_unaligned(val, ptr)                                         \
+        ({                                                              \
+                switch (sizeof(*(ptr))) {                               \
+                case 1:                                                 \
+                        *(ptr) = (val);                                 \
+                        break;                                          \
+                case 2:                                                 \
+                        __put_unaligned_2((val), (__u8 *)(ptr));        \
+                        break;                                          \
+                case 4:                                                 \
+                        __put_unaligned_4((val), (__u8 *)(ptr));        \
+                        break;                                          \
+                case 8:                                                 \
+                        __put_unaligned_8((val), (__u8 *)(ptr));        \
+                        break;                                          \
+                default:                                                \
+                        __bug_unaligned_x(ptr);                         \
+                        break;                                          \
+                }                                                       \
+                (void) 0;                                               \
+        })
+
+
+#else
+
+#define get_unaligned(ptr) (*(ptr))
+#define put_unaligned(val, ptr) ({ *(ptr) = (val); (void) 0; })
+
+#endif
+
+#endif