1 files changed, 118 insertions, 0 deletions

diff --git a/include/asm-arm26/unaligned.h b/include/asm-arm26/unaligned.h
new file mode 100644
index 000000000000..d992782089fd
--- /dev/null
+++ b/include/asm-arm26/unaligned.h
@@ -0,0 +1,118 @@
+#ifndef __ASM_ARM_UNALIGNED_H
+#define __ASM_ARM_UNALIGNED_H
+
+#include <asm/types.h>
+
+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_le(__p)                                       \
+        (__p[0] | __p[1] << 8)
+
+#define __get_unaligned_4_le(__p)                                       \
+        (__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
+
+#define __get_unaligned_le(ptr)                                 \
+        ({                                                      \
+                __typeof__(*(ptr)) __v;                         \
+                __u8 *__p = (__u8 *)(ptr);                      \
+                switch (sizeof(*(ptr))) {                       \
+                case 1: __v = *(ptr);                   break;  \
+                case 2: __v = __get_unaligned_2_le(__p);        break;  \
+                case 4: __v = __get_unaligned_4_le(__p);        break;  \
+                case 8: {                                       \
+                                unsigned int __v1, __v2;        \
+                                __v2 = __get_unaligned_4_le((__p+4)); \
+                                __v1 = __get_unaligned_4_le(__p);       \
+                                __v = ((unsigned long long)__v2 << 32 | __v1);  \
+                        }                                       \
+                        break;                                  \
+                default: __v = __bug_unaligned_x(__p);  break;  \
+                }                                               \
+                __v;                                            \
+        })
+
+static inline void __put_unaligned_2_le(__u32 __v, register __u8 *__p)
+{
+        *__p++ = __v;
+        *__p++ = __v >> 8;
+}
+
+static inline void __put_unaligned_4_le(__u32 __v, register __u8 *__p)
+{
+        __put_unaligned_2_le(__v >> 16, __p + 2);
+        __put_unaligned_2_le(__v, __p);
+}
+
+static inline void __put_unaligned_8_le(const unsigned long long __v, register __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_le(__v >> 32, __p+4);
+        __put_unaligned_4_le(__v, __p);
+}
+
+/*
+ * Try to store an unaligned value as efficiently as possible.
+ */
+#define __put_unaligned_le(val,ptr)                                     \
+        ({                                                      \
+                switch (sizeof(*(ptr))) {                       \
+                case 1:                                         \
+                        *(ptr) = (val);                         \
+                        break;                                  \
+                case 2: __put_unaligned_2_le((val),(__u8 *)(ptr));      \
+                        break;                                  \
+                case 4: __put_unaligned_4_le((val),(__u8 *)(ptr));      \
+                        break;                                  \
+                case 8: __put_unaligned_8_le((val),(__u8 *)(ptr)); \
+                        break;                                  \
+                default: __bug_unaligned_x(ptr);                \
+                        break;                                  \
+                }                                               \
+                (void) 0;                                       \
+        })
+
+/*
+ * Select endianness
+ */
+#define get_unaligned   __get_unaligned_le
+#define put_unaligned   __put_unaligned_le
+
+#endif