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3e9b3112 JK |
1 | /* |
2 | * Copyright (C) 2014 Felix Fietkau <nbd@nbd.name> | |
3 | * Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 | |
7 | * as published by the Free Software Foundation | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | */ | |
14 | ||
15 | #ifndef _LINUX_BITFIELD_H | |
16 | #define _LINUX_BITFIELD_H | |
17 | ||
8001541c | 18 | #include <linux/build_bug.h> |
00b0c9b8 | 19 | #include <asm/byteorder.h> |
3e9b3112 JK |
20 | |
21 | /* | |
22 | * Bitfield access macros | |
23 | * | |
24 | * FIELD_{GET,PREP} macros take as first parameter shifted mask | |
25 | * from which they extract the base mask and shift amount. | |
26 | * Mask must be a compilation time constant. | |
27 | * | |
28 | * Example: | |
29 | * | |
30 | * #define REG_FIELD_A GENMASK(6, 0) | |
31 | * #define REG_FIELD_B BIT(7) | |
32 | * #define REG_FIELD_C GENMASK(15, 8) | |
33 | * #define REG_FIELD_D GENMASK(31, 16) | |
34 | * | |
35 | * Get: | |
36 | * a = FIELD_GET(REG_FIELD_A, reg); | |
37 | * b = FIELD_GET(REG_FIELD_B, reg); | |
38 | * | |
39 | * Set: | |
40 | * reg = FIELD_PREP(REG_FIELD_A, 1) | | |
41 | * FIELD_PREP(REG_FIELD_B, 0) | | |
42 | * FIELD_PREP(REG_FIELD_C, c) | | |
43 | * FIELD_PREP(REG_FIELD_D, 0x40); | |
44 | * | |
45 | * Modify: | |
46 | * reg &= ~REG_FIELD_C; | |
47 | * reg |= FIELD_PREP(REG_FIELD_C, c); | |
48 | */ | |
49 | ||
50 | #define __bf_shf(x) (__builtin_ffsll(x) - 1) | |
51 | ||
52 | #define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \ | |
53 | ({ \ | |
54 | BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \ | |
55 | _pfx "mask is not constant"); \ | |
e36488c8 | 56 | BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \ |
3e9b3112 JK |
57 | BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ |
58 | ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \ | |
59 | _pfx "value too large for the field"); \ | |
60 | BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull, \ | |
61 | _pfx "type of reg too small for mask"); \ | |
62 | __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \ | |
63 | (1ULL << __bf_shf(_mask))); \ | |
64 | }) | |
65 | ||
1697599e JK |
66 | /** |
67 | * FIELD_FIT() - check if value fits in the field | |
68 | * @_mask: shifted mask defining the field's length and position | |
69 | * @_val: value to test against the field | |
70 | * | |
71 | * Return: true if @_val can fit inside @_mask, false if @_val is too big. | |
72 | */ | |
73 | #define FIELD_FIT(_mask, _val) \ | |
74 | ({ \ | |
75 | __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_FIT: "); \ | |
76 | !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \ | |
77 | }) | |
78 | ||
3e9b3112 JK |
79 | /** |
80 | * FIELD_PREP() - prepare a bitfield element | |
81 | * @_mask: shifted mask defining the field's length and position | |
82 | * @_val: value to put in the field | |
83 | * | |
84 | * FIELD_PREP() masks and shifts up the value. The result should | |
85 | * be combined with other fields of the bitfield using logical OR. | |
86 | */ | |
87 | #define FIELD_PREP(_mask, _val) \ | |
88 | ({ \ | |
89 | __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \ | |
90 | ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \ | |
91 | }) | |
92 | ||
93 | /** | |
94 | * FIELD_GET() - extract a bitfield element | |
95 | * @_mask: shifted mask defining the field's length and position | |
72407674 | 96 | * @_reg: value of entire bitfield |
3e9b3112 JK |
97 | * |
98 | * FIELD_GET() extracts the field specified by @_mask from the | |
99 | * bitfield passed in as @_reg by masking and shifting it down. | |
100 | */ | |
101 | #define FIELD_GET(_mask, _reg) \ | |
102 | ({ \ | |
103 | __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \ | |
104 | (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \ | |
105 | }) | |
106 | ||
e7d4a95d | 107 | extern void __compiletime_error("value doesn't fit into mask") |
00b0c9b8 AV |
108 | __field_overflow(void); |
109 | extern void __compiletime_error("bad bitfield mask") | |
110 | __bad_mask(void); | |
111 | static __always_inline u64 field_multiplier(u64 field) | |
112 | { | |
113 | if ((field | (field - 1)) & ((field | (field - 1)) + 1)) | |
114 | __bad_mask(); | |
115 | return field & -field; | |
116 | } | |
117 | static __always_inline u64 field_mask(u64 field) | |
118 | { | |
119 | return field / field_multiplier(field); | |
120 | } | |
121 | #define ____MAKE_OP(type,base,to,from) \ | |
122 | static __always_inline __##type type##_encode_bits(base v, base field) \ | |
123 | { \ | |
e7d4a95d JB |
124 | if (__builtin_constant_p(v) && (v & ~field_mask(field))) \ |
125 | __field_overflow(); \ | |
00b0c9b8 AV |
126 | return to((v & field_mask(field)) * field_multiplier(field)); \ |
127 | } \ | |
128 | static __always_inline __##type type##_replace_bits(__##type old, \ | |
129 | base val, base field) \ | |
130 | { \ | |
131 | return (old & ~to(field)) | type##_encode_bits(val, field); \ | |
132 | } \ | |
133 | static __always_inline void type##p_replace_bits(__##type *p, \ | |
134 | base val, base field) \ | |
135 | { \ | |
136 | *p = (*p & ~to(field)) | type##_encode_bits(val, field); \ | |
137 | } \ | |
138 | static __always_inline base type##_get_bits(__##type v, base field) \ | |
139 | { \ | |
140 | return (from(v) & field)/field_multiplier(field); \ | |
141 | } | |
142 | #define __MAKE_OP(size) \ | |
143 | ____MAKE_OP(le##size,u##size,cpu_to_le##size,le##size##_to_cpu) \ | |
144 | ____MAKE_OP(be##size,u##size,cpu_to_be##size,be##size##_to_cpu) \ | |
145 | ____MAKE_OP(u##size,u##size,,) | |
37a3862e | 146 | ____MAKE_OP(u8,u8,,) |
00b0c9b8 AV |
147 | __MAKE_OP(16) |
148 | __MAKE_OP(32) | |
149 | __MAKE_OP(64) | |
150 | #undef __MAKE_OP | |
151 | #undef ____MAKE_OP | |
152 | ||
3e9b3112 | 153 | #endif |