diff options
| author | Harvey Harrison <harvey.harrison@gmail.com> | 2008-04-29 04:03:27 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 11:06:27 -0400 |
| commit | 064106a91be5e76cb42c1ddf5d3871e3a1bd2a23 (patch) | |
| tree | 7bb3931857c933343abf9a55d663e8a9b8af13ae /include/linux/unaligned/generic.h | |
| parent | dddfbaf8f86894415abb8256b55da68dab966ebe (diff) | |
kernel: add common infrastructure for unaligned access
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>
Diffstat (limited to 'include/linux/unaligned/generic.h')
| -rw-r--r-- | include/linux/unaligned/generic.h | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/include/linux/unaligned/generic.h b/include/linux/unaligned/generic.h new file mode 100644 index 000000000000..02d97ff3df70 --- /dev/null +++ b/include/linux/unaligned/generic.h | |||
| @@ -0,0 +1,68 @@ | |||
| 1 | #ifndef _LINUX_UNALIGNED_GENERIC_H | ||
| 2 | #define _LINUX_UNALIGNED_GENERIC_H | ||
| 3 | |||
| 4 | /* | ||
| 5 | * Cause a link-time error if we try an unaligned access other than | ||
| 6 | * 1,2,4 or 8 bytes long | ||
| 7 | */ | ||
| 8 | extern void __bad_unaligned_access_size(void); | ||
| 9 | |||
| 10 | #define __get_unaligned_le(ptr) ((__force typeof(*(ptr)))({ \ | ||
| 11 | __builtin_choose_expr(sizeof(*(ptr)) == 1, *(ptr), \ | ||
| 12 | __builtin_choose_expr(sizeof(*(ptr)) == 2, get_unaligned_le16((ptr)), \ | ||
| 13 | __builtin_choose_expr(sizeof(*(ptr)) == 4, get_unaligned_le32((ptr)), \ | ||
| 14 | __builtin_choose_expr(sizeof(*(ptr)) == 8, get_unaligned_le64((ptr)), \ | ||
| 15 | __bad_unaligned_access_size())))); \ | ||
| 16 | })) | ||
| 17 | |||
| 18 | #define __get_unaligned_be(ptr) ((__force typeof(*(ptr)))({ \ | ||
| 19 | __builtin_choose_expr(sizeof(*(ptr)) == 1, *(ptr), \ | ||
| 20 | __builtin_choose_expr(sizeof(*(ptr)) == 2, get_unaligned_be16((ptr)), \ | ||
| 21 | __builtin_choose_expr(sizeof(*(ptr)) == 4, get_unaligned_be32((ptr)), \ | ||
| 22 | __builtin_choose_expr(sizeof(*(ptr)) == 8, get_unaligned_be64((ptr)), \ | ||
| 23 | __bad_unaligned_access_size())))); \ | ||
| 24 | })) | ||
| 25 | |||
| 26 | #define __put_unaligned_le(val, ptr) ({ \ | ||
| 27 | void *__gu_p = (ptr); \ | ||
| 28 | switch (sizeof(*(ptr))) { \ | ||
| 29 | case 1: \ | ||
| 30 | *(u8 *)__gu_p = (__force u8)(val); \ | ||
| 31 | break; \ | ||
| 32 | case 2: \ | ||
| 33 | put_unaligned_le16((__force u16)(val), __gu_p); \ | ||
| 34 | break; \ | ||
| 35 | case 4: \ | ||
| 36 | put_unaligned_le32((__force u32)(val), __gu_p); \ | ||
| 37 | break; \ | ||
| 38 | case 8: \ | ||
| 39 | put_unaligned_le64((__force u64)(val), __gu_p); \ | ||
| 40 | break; \ | ||
| 41 | default: \ | ||
| 42 | __bad_unaligned_access_size(); \ | ||
| 43 | break; \ | ||
| 44 | } \ | ||
| 45 | (void)0; }) | ||
| 46 | |||
| 47 | #define __put_unaligned_be(val, ptr) ({ \ | ||
| 48 | void *__gu_p = (ptr); \ | ||
| 49 | switch (sizeof(*(ptr))) { \ | ||
| 50 | case 1: \ | ||
| 51 | *(u8 *)__gu_p = (__force u8)(val); \ | ||
| 52 | break; \ | ||
| 53 | case 2: \ | ||
| 54 | put_unaligned_be16((__force u16)(val), __gu_p); \ | ||
| 55 | break; \ | ||
| 56 | case 4: \ | ||
| 57 | put_unaligned_be32((__force u32)(val), __gu_p); \ | ||
| 58 | break; \ | ||
| 59 | case 8: \ | ||
| 60 | put_unaligned_be64((__force u64)(val), __gu_p); \ | ||
| 61 | break; \ | ||
| 62 | default: \ | ||
| 63 | __bad_unaligned_access_size(); \ | ||
| 64 | break; \ | ||
| 65 | } \ | ||
| 66 | (void)0; }) | ||
| 67 | |||
| 68 | #endif /* _LINUX_UNALIGNED_GENERIC_H */ | ||