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