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1802d0be | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
3e9b3112 JK |
2 | /* |
3 | * Copyright (C) 2014 Felix Fietkau <nbd@nbd.name> | |
4 | * Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com> | |
3e9b3112 JK |
5 | */ |
6 | ||
7 | #ifndef _LINUX_BITFIELD_H | |
8 | #define _LINUX_BITFIELD_H | |
9 | ||
8001541c | 10 | #include <linux/build_bug.h> |
00b0c9b8 | 11 | #include <asm/byteorder.h> |
3e9b3112 JK |
12 | |
13 | /* | |
14 | * Bitfield access macros | |
15 | * | |
16 | * FIELD_{GET,PREP} macros take as first parameter shifted mask | |
17 | * from which they extract the base mask and shift amount. | |
18 | * Mask must be a compilation time constant. | |
19 | * | |
20 | * Example: | |
21 | * | |
22 | * #define REG_FIELD_A GENMASK(6, 0) | |
23 | * #define REG_FIELD_B BIT(7) | |
24 | * #define REG_FIELD_C GENMASK(15, 8) | |
25 | * #define REG_FIELD_D GENMASK(31, 16) | |
26 | * | |
27 | * Get: | |
28 | * a = FIELD_GET(REG_FIELD_A, reg); | |
29 | * b = FIELD_GET(REG_FIELD_B, reg); | |
30 | * | |
31 | * Set: | |
32 | * reg = FIELD_PREP(REG_FIELD_A, 1) | | |
33 | * FIELD_PREP(REG_FIELD_B, 0) | | |
34 | * FIELD_PREP(REG_FIELD_C, c) | | |
35 | * FIELD_PREP(REG_FIELD_D, 0x40); | |
36 | * | |
37 | * Modify: | |
38 | * reg &= ~REG_FIELD_C; | |
39 | * reg |= FIELD_PREP(REG_FIELD_C, c); | |
40 | */ | |
41 | ||
42 | #define __bf_shf(x) (__builtin_ffsll(x) - 1) | |
43 | ||
bff8c384 PZ |
44 | #define __scalar_type_to_unsigned_cases(type) \ |
45 | unsigned type: (unsigned type)0, \ | |
46 | signed type: (unsigned type)0 | |
47 | ||
48 | #define __unsigned_scalar_typeof(x) typeof( \ | |
49 | _Generic((x), \ | |
50 | char: (unsigned char)0, \ | |
51 | __scalar_type_to_unsigned_cases(char), \ | |
52 | __scalar_type_to_unsigned_cases(short), \ | |
53 | __scalar_type_to_unsigned_cases(int), \ | |
54 | __scalar_type_to_unsigned_cases(long), \ | |
55 | __scalar_type_to_unsigned_cases(long long), \ | |
56 | default: (x))) | |
57 | ||
58 | #define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x)) | |
59 | ||
3e9b3112 JK |
60 | #define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \ |
61 | ({ \ | |
62 | BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \ | |
63 | _pfx "mask is not constant"); \ | |
e36488c8 | 64 | BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \ |
3e9b3112 JK |
65 | BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ |
66 | ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \ | |
67 | _pfx "value too large for the field"); \ | |
bff8c384 PZ |
68 | BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \ |
69 | __bf_cast_unsigned(_reg, ~0ull), \ | |
3e9b3112 JK |
70 | _pfx "type of reg too small for mask"); \ |
71 | __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \ | |
72 | (1ULL << __bf_shf(_mask))); \ | |
73 | }) | |
74 | ||
e31a5016 AE |
75 | /** |
76 | * FIELD_MAX() - produce the maximum value representable by a field | |
77 | * @_mask: shifted mask defining the field's length and position | |
78 | * | |
79 | * FIELD_MAX() returns the maximum value that can be held in the field | |
80 | * specified by @_mask. | |
81 | */ | |
82 | #define FIELD_MAX(_mask) \ | |
83 | ({ \ | |
84 | __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \ | |
85 | (typeof(_mask))((_mask) >> __bf_shf(_mask)); \ | |
86 | }) | |
87 | ||
1697599e JK |
88 | /** |
89 | * FIELD_FIT() - check if value fits in the field | |
90 | * @_mask: shifted mask defining the field's length and position | |
91 | * @_val: value to test against the field | |
92 | * | |
93 | * Return: true if @_val can fit inside @_mask, false if @_val is too big. | |
94 | */ | |
95 | #define FIELD_FIT(_mask, _val) \ | |
96 | ({ \ | |
444da3f5 | 97 | __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \ |
1697599e JK |
98 | !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \ |
99 | }) | |
100 | ||
3e9b3112 JK |
101 | /** |
102 | * FIELD_PREP() - prepare a bitfield element | |
103 | * @_mask: shifted mask defining the field's length and position | |
104 | * @_val: value to put in the field | |
105 | * | |
106 | * FIELD_PREP() masks and shifts up the value. The result should | |
107 | * be combined with other fields of the bitfield using logical OR. | |
108 | */ | |
109 | #define FIELD_PREP(_mask, _val) \ | |
110 | ({ \ | |
111 | __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \ | |
112 | ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \ | |
113 | }) | |
114 | ||
115 | /** | |
116 | * FIELD_GET() - extract a bitfield element | |
117 | * @_mask: shifted mask defining the field's length and position | |
72407674 | 118 | * @_reg: value of entire bitfield |
3e9b3112 JK |
119 | * |
120 | * FIELD_GET() extracts the field specified by @_mask from the | |
121 | * bitfield passed in as @_reg by masking and shifting it down. | |
122 | */ | |
123 | #define FIELD_GET(_mask, _reg) \ | |
124 | ({ \ | |
125 | __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \ | |
126 | (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \ | |
127 | }) | |
128 | ||
e7d4a95d | 129 | extern void __compiletime_error("value doesn't fit into mask") |
00b0c9b8 AV |
130 | __field_overflow(void); |
131 | extern void __compiletime_error("bad bitfield mask") | |
132 | __bad_mask(void); | |
133 | static __always_inline u64 field_multiplier(u64 field) | |
134 | { | |
135 | if ((field | (field - 1)) & ((field | (field - 1)) + 1)) | |
136 | __bad_mask(); | |
137 | return field & -field; | |
138 | } | |
139 | static __always_inline u64 field_mask(u64 field) | |
140 | { | |
141 | return field / field_multiplier(field); | |
142 | } | |
e31a5016 | 143 | #define field_max(field) ((typeof(field))field_mask(field)) |
00b0c9b8 AV |
144 | #define ____MAKE_OP(type,base,to,from) \ |
145 | static __always_inline __##type type##_encode_bits(base v, base field) \ | |
146 | { \ | |
e7d4a95d JB |
147 | if (__builtin_constant_p(v) && (v & ~field_mask(field))) \ |
148 | __field_overflow(); \ | |
00b0c9b8 AV |
149 | return to((v & field_mask(field)) * field_multiplier(field)); \ |
150 | } \ | |
151 | static __always_inline __##type type##_replace_bits(__##type old, \ | |
152 | base val, base field) \ | |
153 | { \ | |
154 | return (old & ~to(field)) | type##_encode_bits(val, field); \ | |
155 | } \ | |
156 | static __always_inline void type##p_replace_bits(__##type *p, \ | |
157 | base val, base field) \ | |
158 | { \ | |
159 | *p = (*p & ~to(field)) | type##_encode_bits(val, field); \ | |
160 | } \ | |
161 | static __always_inline base type##_get_bits(__##type v, base field) \ | |
162 | { \ | |
163 | return (from(v) & field)/field_multiplier(field); \ | |
164 | } | |
165 | #define __MAKE_OP(size) \ | |
166 | ____MAKE_OP(le##size,u##size,cpu_to_le##size,le##size##_to_cpu) \ | |
167 | ____MAKE_OP(be##size,u##size,cpu_to_be##size,be##size##_to_cpu) \ | |
168 | ____MAKE_OP(u##size,u##size,,) | |
37a3862e | 169 | ____MAKE_OP(u8,u8,,) |
00b0c9b8 AV |
170 | __MAKE_OP(16) |
171 | __MAKE_OP(32) | |
172 | __MAKE_OP(64) | |
173 | #undef __MAKE_OP | |
174 | #undef ____MAKE_OP | |
175 | ||
3e9b3112 | 176 | #endif |