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
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+/* 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