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| author | Nicolas Saenz Julienne <nsaenzjulienne@suse.de> | 2020-05-25 13:39:56 +0200 |
|---|---|---|
| committer | Matthias Brugger <mbrugger@suse.com> | 2020-07-10 11:47:12 +0200 |
| commit | c92921bb52a7e104e0a48740d518c41ec4c86097 (patch) | |
| tree | d9db1710eb621a94ee13765c1b1385084bbb69cd /include/linux/bitfield.h | |
| parent | d69ddf24944162745665a45fef00a2115d371dbe (diff) | |
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>
Diffstat (limited to 'include/linux/bitfield.h')
| -rw-r--r-- | include/linux/bitfield.h | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index 8b9d6fff00..7ad02f8cbb 100644 --- a/include/linux/bitfield.h +++ b/include/linux/bitfield.h @@ -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 |