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064106a91b
Create a linux/unaligned directory similar in spirit to the linux/byteorder
folder to hold generic implementations collected from various arches.
Currently there are five implementations:
1) packed_struct.h: C-struct based, from asm-generic/unaligned.h
2) le_byteshift.h: Open coded byte-swapping, heavily based on asm-arm
3) be_byteshift.h: Open coded byte-swapping, heavily based on asm-arm
4) memmove.h: taken from multiple implementations in tree
5) access_ok.h: taken from x86 and others, unaligned access is ok.
All of the new implementations checks for sizes not equal to 1,2,4,8
and will fail to link.
API additions:
get_unaligned_{le16|le32|le64|be16|be32|be64}(p) which is meant to replace
code of the form:
le16_to_cpu(get_unaligned((__le16 *)p));
put_unaligned_{le16|le32|le64|be16|be32|be64}(val, pointer) which is meant to
replace code of the form:
put_unaligned(cpu_to_le16(val), (__le16 *)p);
The headers that arches should include from their asm/unaligned.h:
access_ok.h : Wrappers of the byteswapping functions in asm/byteorder
Choose a particular implementation for little-endian access:
le_byteshift.h
le_memmove.h (arch must be LE)
le_struct.h (arch must be LE)
Choose a particular implementation for big-endian access:
be_byteshift.h
be_memmove.h (arch must be BE)
be_struct.h (arch must be BE)
After including as needed from the above, include unaligned/generic.h and
define your arch's get/put_unaligned as (for LE):
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
69 lines
2.1 KiB
C
69 lines
2.1 KiB
C
#ifndef _LINUX_UNALIGNED_GENERIC_H
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#define _LINUX_UNALIGNED_GENERIC_H
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/*
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* Cause a link-time error if we try an unaligned access other than
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* 1,2,4 or 8 bytes long
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*/
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extern void __bad_unaligned_access_size(void);
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#define __get_unaligned_le(ptr) ((__force typeof(*(ptr)))({ \
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__builtin_choose_expr(sizeof(*(ptr)) == 1, *(ptr), \
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__builtin_choose_expr(sizeof(*(ptr)) == 2, get_unaligned_le16((ptr)), \
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__builtin_choose_expr(sizeof(*(ptr)) == 4, get_unaligned_le32((ptr)), \
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__builtin_choose_expr(sizeof(*(ptr)) == 8, get_unaligned_le64((ptr)), \
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__bad_unaligned_access_size())))); \
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}))
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#define __get_unaligned_be(ptr) ((__force typeof(*(ptr)))({ \
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__builtin_choose_expr(sizeof(*(ptr)) == 1, *(ptr), \
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__builtin_choose_expr(sizeof(*(ptr)) == 2, get_unaligned_be16((ptr)), \
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__builtin_choose_expr(sizeof(*(ptr)) == 4, get_unaligned_be32((ptr)), \
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__builtin_choose_expr(sizeof(*(ptr)) == 8, get_unaligned_be64((ptr)), \
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__bad_unaligned_access_size())))); \
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}))
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#define __put_unaligned_le(val, ptr) ({ \
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void *__gu_p = (ptr); \
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switch (sizeof(*(ptr))) { \
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case 1: \
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*(u8 *)__gu_p = (__force u8)(val); \
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break; \
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case 2: \
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put_unaligned_le16((__force u16)(val), __gu_p); \
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break; \
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case 4: \
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put_unaligned_le32((__force u32)(val), __gu_p); \
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break; \
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case 8: \
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put_unaligned_le64((__force u64)(val), __gu_p); \
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break; \
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default: \
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__bad_unaligned_access_size(); \
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break; \
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} \
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(void)0; })
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#define __put_unaligned_be(val, ptr) ({ \
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void *__gu_p = (ptr); \
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switch (sizeof(*(ptr))) { \
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case 1: \
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*(u8 *)__gu_p = (__force u8)(val); \
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break; \
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case 2: \
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put_unaligned_be16((__force u16)(val), __gu_p); \
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break; \
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case 4: \
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put_unaligned_be32((__force u32)(val), __gu_p); \
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break; \
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case 8: \
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put_unaligned_be64((__force u64)(val), __gu_p); \
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break; \
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default: \
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__bad_unaligned_access_size(); \
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break; \
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} \
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(void)0; })
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#endif /* _LINUX_UNALIGNED_GENERIC_H */
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