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linux/bitfield.h: Add primitives for manipulating bitfields both in host- and fixed-endian 

Imports Al Viro's original Linux commit 00b0c9b82663a, which contains
an in depth explanation and two fixes from Johannes Berg:
 e7d4a95da86e0 "bitfield: fix *_encode_bits()",
 37a3862e12382 "bitfield: add u8 helpers".

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
[s.nawrocki: added empty lines between functions and macros]
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
[mb: squash fix including byteorder.h]
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
This commit is contained in:
Nicolas Saenz Julienne 2020-05-25 13:39:56 +02:00 committed by Matthias Brugger
parent d69ddf2494
commit c92921bb52
1 changed files with 53 additions and 0 deletions
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53
include/linux/bitfield.h
View File

@ -16,6 +16,7 @@
#define _LINUX_BITFIELD_H
#include <linux/bug.h>
#include <asm/byteorder.h>
/*
* Bitfield access macros
@ -103,4 +104,56 @@
(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
})
extern void __compiletime_error("value doesn't fit into mask")
__field_overflow(void);
extern void __compiletime_error("bad bitfield mask")
__bad_mask(void);
static __always_inline u64 field_multiplier(u64 field)
{
if ((field | (field - 1)) & ((field | (field - 1)) + 1))
__bad_mask();
return field & -field;
}
static __always_inline u64 field_mask(u64 field)
{
return field / field_multiplier(field);
}
#define ____MAKE_OP(type, base, to, from) \
static __always_inline __##type type##_encode_bits(base v, base field) \
{ \
if (__builtin_constant_p(v) && (v & ~field_mask(field))) \
__field_overflow(); \
return to((v & field_mask(field)) * field_multiplier(field)); \
} \
static __always_inline __##type type##_replace_bits(__##type old, \
base val, base field) \
{ \
return (old & ~to(field)) | type##_encode_bits(val, field); \
} \
static __always_inline void type##p_replace_bits(__##type * p, \
base val, base field) \
{ \
*p = (*p & ~to(field)) | type##_encode_bits(val, field); \
} \
static __always_inline base type##_get_bits(__##type v, base field) \
{ \
return (from(v) & field) / field_multiplier(field); \
}
#define __MAKE_OP(size) \
____MAKE_OP(le##size, u##size, cpu_to_le##size, le##size##_to_cpu) \
____MAKE_OP(be##size, u##size, cpu_to_be##size, be##size##_to_cpu) \
____MAKE_OP(u##size, u##size, ,)
____MAKE_OP(u8, u8, ,)
__MAKE_OP(16)
__MAKE_OP(32)
__MAKE_OP(64)
#undef __MAKE_OP
#undef ____MAKE_OP
#endif