11802d0beSThomas Gleixner /* SPDX-License-Identifier: GPL-2.0-only */
23e9b3112SJakub Kicinski /*
33e9b3112SJakub Kicinski * Copyright (C) 2014 Felix Fietkau <nbd@nbd.name>
43e9b3112SJakub Kicinski * Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
53e9b3112SJakub Kicinski */
63e9b3112SJakub Kicinski
73e9b3112SJakub Kicinski #ifndef _LINUX_BITFIELD_H
83e9b3112SJakub Kicinski #define _LINUX_BITFIELD_H
93e9b3112SJakub Kicinski
108001541cSMasahiro Yamada #include <linux/build_bug.h>
1100b0c9b8SAl Viro #include <asm/byteorder.h>
123e9b3112SJakub Kicinski
133e9b3112SJakub Kicinski /*
143e9b3112SJakub Kicinski * Bitfield access macros
153e9b3112SJakub Kicinski *
163e9b3112SJakub Kicinski * FIELD_{GET,PREP} macros take as first parameter shifted mask
173e9b3112SJakub Kicinski * from which they extract the base mask and shift amount.
183e9b3112SJakub Kicinski * Mask must be a compilation time constant.
193e9b3112SJakub Kicinski *
203e9b3112SJakub Kicinski * Example:
213e9b3112SJakub Kicinski *
2225cb5b7aSAndy Shevchenko * #include <linux/bitfield.h>
2325cb5b7aSAndy Shevchenko * #include <linux/bits.h>
2425cb5b7aSAndy Shevchenko *
253e9b3112SJakub Kicinski * #define REG_FIELD_A GENMASK(6, 0)
263e9b3112SJakub Kicinski * #define REG_FIELD_B BIT(7)
273e9b3112SJakub Kicinski * #define REG_FIELD_C GENMASK(15, 8)
283e9b3112SJakub Kicinski * #define REG_FIELD_D GENMASK(31, 16)
293e9b3112SJakub Kicinski *
303e9b3112SJakub Kicinski * Get:
313e9b3112SJakub Kicinski * a = FIELD_GET(REG_FIELD_A, reg);
323e9b3112SJakub Kicinski * b = FIELD_GET(REG_FIELD_B, reg);
333e9b3112SJakub Kicinski *
343e9b3112SJakub Kicinski * Set:
353e9b3112SJakub Kicinski * reg = FIELD_PREP(REG_FIELD_A, 1) |
363e9b3112SJakub Kicinski * FIELD_PREP(REG_FIELD_B, 0) |
373e9b3112SJakub Kicinski * FIELD_PREP(REG_FIELD_C, c) |
383e9b3112SJakub Kicinski * FIELD_PREP(REG_FIELD_D, 0x40);
393e9b3112SJakub Kicinski *
403e9b3112SJakub Kicinski * Modify:
413e9b3112SJakub Kicinski * reg &= ~REG_FIELD_C;
423e9b3112SJakub Kicinski * reg |= FIELD_PREP(REG_FIELD_C, c);
433e9b3112SJakub Kicinski */
443e9b3112SJakub Kicinski
453e9b3112SJakub Kicinski #define __bf_shf(x) (__builtin_ffsll(x) - 1)
463e9b3112SJakub Kicinski
47bff8c384SPeter Zijlstra #define __scalar_type_to_unsigned_cases(type) \
48bff8c384SPeter Zijlstra unsigned type: (unsigned type)0, \
49bff8c384SPeter Zijlstra signed type: (unsigned type)0
50bff8c384SPeter Zijlstra
51bff8c384SPeter Zijlstra #define __unsigned_scalar_typeof(x) typeof( \
52bff8c384SPeter Zijlstra _Generic((x), \
53bff8c384SPeter Zijlstra char: (unsigned char)0, \
54bff8c384SPeter Zijlstra __scalar_type_to_unsigned_cases(char), \
55bff8c384SPeter Zijlstra __scalar_type_to_unsigned_cases(short), \
56bff8c384SPeter Zijlstra __scalar_type_to_unsigned_cases(int), \
57bff8c384SPeter Zijlstra __scalar_type_to_unsigned_cases(long), \
58bff8c384SPeter Zijlstra __scalar_type_to_unsigned_cases(long long), \
59bff8c384SPeter Zijlstra default: (x)))
60bff8c384SPeter Zijlstra
61bff8c384SPeter Zijlstra #define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x))
62bff8c384SPeter Zijlstra
633e9b3112SJakub Kicinski #define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
643e9b3112SJakub Kicinski ({ \
653e9b3112SJakub Kicinski BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \
663e9b3112SJakub Kicinski _pfx "mask is not constant"); \
67e36488c8SArnd Bergmann BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \
683e9b3112SJakub Kicinski BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \
693e9b3112SJakub Kicinski ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
703e9b3112SJakub Kicinski _pfx "value too large for the field"); \
71bff8c384SPeter Zijlstra BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \
72bff8c384SPeter Zijlstra __bf_cast_unsigned(_reg, ~0ull), \
733e9b3112SJakub Kicinski _pfx "type of reg too small for mask"); \
743e9b3112SJakub Kicinski __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
753e9b3112SJakub Kicinski (1ULL << __bf_shf(_mask))); \
763e9b3112SJakub Kicinski })
773e9b3112SJakub Kicinski
783e9b3112SJakub Kicinski /**
79e31a5016SAlex Elder * FIELD_MAX() - produce the maximum value representable by a field
80e31a5016SAlex Elder * @_mask: shifted mask defining the field's length and position
81e31a5016SAlex Elder *
82e31a5016SAlex Elder * FIELD_MAX() returns the maximum value that can be held in the field
83e31a5016SAlex Elder * specified by @_mask.
84e31a5016SAlex Elder */
85e31a5016SAlex Elder #define FIELD_MAX(_mask) \
86e31a5016SAlex Elder ({ \
87e31a5016SAlex Elder __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \
88e31a5016SAlex Elder (typeof(_mask))((_mask) >> __bf_shf(_mask)); \
89e31a5016SAlex Elder })
90e31a5016SAlex Elder
91e31a5016SAlex Elder /**
921697599eSJakub Kicinski * FIELD_FIT() - check if value fits in the field
931697599eSJakub Kicinski * @_mask: shifted mask defining the field's length and position
941697599eSJakub Kicinski * @_val: value to test against the field
951697599eSJakub Kicinski *
961697599eSJakub Kicinski * Return: true if @_val can fit inside @_mask, false if @_val is too big.
971697599eSJakub Kicinski */
981697599eSJakub Kicinski #define FIELD_FIT(_mask, _val) \
991697599eSJakub Kicinski ({ \
100444da3f5SJakub Kicinski __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \
1011697599eSJakub Kicinski !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
1021697599eSJakub Kicinski })
1031697599eSJakub Kicinski
1041697599eSJakub Kicinski /**
1053e9b3112SJakub Kicinski * FIELD_PREP() - prepare a bitfield element
1063e9b3112SJakub Kicinski * @_mask: shifted mask defining the field's length and position
1073e9b3112SJakub Kicinski * @_val: value to put in the field
1083e9b3112SJakub Kicinski *
1093e9b3112SJakub Kicinski * FIELD_PREP() masks and shifts up the value. The result should
1103e9b3112SJakub Kicinski * be combined with other fields of the bitfield using logical OR.
1113e9b3112SJakub Kicinski */
1123e9b3112SJakub Kicinski #define FIELD_PREP(_mask, _val) \
1133e9b3112SJakub Kicinski ({ \
1143e9b3112SJakub Kicinski __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \
1153e9b3112SJakub Kicinski ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \
1163e9b3112SJakub Kicinski })
1173e9b3112SJakub Kicinski
118*e2192de5SJohannes Berg #define __BF_CHECK_POW2(n) BUILD_BUG_ON_ZERO(((n) & ((n) - 1)) != 0)
119*e2192de5SJohannes Berg
120*e2192de5SJohannes Berg /**
121*e2192de5SJohannes Berg * FIELD_PREP_CONST() - prepare a constant bitfield element
122*e2192de5SJohannes Berg * @_mask: shifted mask defining the field's length and position
123*e2192de5SJohannes Berg * @_val: value to put in the field
124*e2192de5SJohannes Berg *
125*e2192de5SJohannes Berg * FIELD_PREP_CONST() masks and shifts up the value. The result should
126*e2192de5SJohannes Berg * be combined with other fields of the bitfield using logical OR.
127*e2192de5SJohannes Berg *
128*e2192de5SJohannes Berg * Unlike FIELD_PREP() this is a constant expression and can therefore
129*e2192de5SJohannes Berg * be used in initializers. Error checking is less comfortable for this
130*e2192de5SJohannes Berg * version, and non-constant masks cannot be used.
131*e2192de5SJohannes Berg */
132*e2192de5SJohannes Berg #define FIELD_PREP_CONST(_mask, _val) \
133*e2192de5SJohannes Berg ( \
134*e2192de5SJohannes Berg /* mask must be non-zero */ \
135*e2192de5SJohannes Berg BUILD_BUG_ON_ZERO((_mask) == 0) + \
136*e2192de5SJohannes Berg /* check if value fits */ \
137*e2192de5SJohannes Berg BUILD_BUG_ON_ZERO(~((_mask) >> __bf_shf(_mask)) & (_val)) + \
138*e2192de5SJohannes Berg /* check if mask is contiguous */ \
139*e2192de5SJohannes Berg __BF_CHECK_POW2((_mask) + (1ULL << __bf_shf(_mask))) + \
140*e2192de5SJohannes Berg /* and create the value */ \
141*e2192de5SJohannes Berg (((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask)) \
142*e2192de5SJohannes Berg )
143*e2192de5SJohannes Berg
1443e9b3112SJakub Kicinski /**
1453e9b3112SJakub Kicinski * FIELD_GET() - extract a bitfield element
1463e9b3112SJakub Kicinski * @_mask: shifted mask defining the field's length and position
14772407674SMasahiro Yamada * @_reg: value of entire bitfield
1483e9b3112SJakub Kicinski *
1493e9b3112SJakub Kicinski * FIELD_GET() extracts the field specified by @_mask from the
1503e9b3112SJakub Kicinski * bitfield passed in as @_reg by masking and shifting it down.
1513e9b3112SJakub Kicinski */
1523e9b3112SJakub Kicinski #define FIELD_GET(_mask, _reg) \
1533e9b3112SJakub Kicinski ({ \
1543e9b3112SJakub Kicinski __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \
1553e9b3112SJakub Kicinski (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
1563e9b3112SJakub Kicinski })
1573e9b3112SJakub Kicinski
158e7d4a95dSJohannes Berg extern void __compiletime_error("value doesn't fit into mask")
15900b0c9b8SAl Viro __field_overflow(void);
16000b0c9b8SAl Viro extern void __compiletime_error("bad bitfield mask")
16100b0c9b8SAl Viro __bad_mask(void);
field_multiplier(u64 field)16200b0c9b8SAl Viro static __always_inline u64 field_multiplier(u64 field)
16300b0c9b8SAl Viro {
16400b0c9b8SAl Viro if ((field | (field - 1)) & ((field | (field - 1)) + 1))
16500b0c9b8SAl Viro __bad_mask();
16600b0c9b8SAl Viro return field & -field;
16700b0c9b8SAl Viro }
field_mask(u64 field)16800b0c9b8SAl Viro static __always_inline u64 field_mask(u64 field)
16900b0c9b8SAl Viro {
17000b0c9b8SAl Viro return field / field_multiplier(field);
17100b0c9b8SAl Viro }
172e31a5016SAlex Elder #define field_max(field) ((typeof(field))field_mask(field))
17300b0c9b8SAl Viro #define ____MAKE_OP(type,base,to,from) \
17400b0c9b8SAl Viro static __always_inline __##type type##_encode_bits(base v, base field) \
17500b0c9b8SAl Viro { \
176e7d4a95dSJohannes Berg if (__builtin_constant_p(v) && (v & ~field_mask(field))) \
17700b0c9b8SAl Viro __field_overflow(); \
17800b0c9b8SAl Viro return to((v & field_mask(field)) * field_multiplier(field)); \
17900b0c9b8SAl Viro } \
18000b0c9b8SAl Viro static __always_inline __##type type##_replace_bits(__##type old, \
18100b0c9b8SAl Viro base val, base field) \
18200b0c9b8SAl Viro { \
18300b0c9b8SAl Viro return (old & ~to(field)) | type##_encode_bits(val, field); \
18400b0c9b8SAl Viro } \
18500b0c9b8SAl Viro static __always_inline void type##p_replace_bits(__##type *p, \
18600b0c9b8SAl Viro base val, base field) \
18700b0c9b8SAl Viro { \
18800b0c9b8SAl Viro *p = (*p & ~to(field)) | type##_encode_bits(val, field); \
18900b0c9b8SAl Viro } \
19000b0c9b8SAl Viro static __always_inline base type##_get_bits(__##type v, base field) \
19100b0c9b8SAl Viro { \
19200b0c9b8SAl Viro return (from(v) & field)/field_multiplier(field); \
19300b0c9b8SAl Viro }
19400b0c9b8SAl Viro #define __MAKE_OP(size) \
19500b0c9b8SAl Viro ____MAKE_OP(le##size,u##size,cpu_to_le##size,le##size##_to_cpu) \
19600b0c9b8SAl Viro ____MAKE_OP(be##size,u##size,cpu_to_be##size,be##size##_to_cpu) \
19700b0c9b8SAl Viro ____MAKE_OP(u##size,u##size,,)
19837a3862eSJohannes Berg ____MAKE_OP(u8,u8,,)
19900b0c9b8SAl Viro __MAKE_OP(16)
20000b0c9b8SAl Viro __MAKE_OP(32)
20100b0c9b8SAl Viro __MAKE_OP(64)
20200b0c9b8SAl Viro #undef __MAKE_OP
20300b0c9b8SAl Viro #undef ____MAKE_OP
20400b0c9b8SAl Viro
2053e9b3112SJakub Kicinski #endif
206