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| 1 | +/* SPDX-License-Identifier: GPL-2.0-only */ |
| 2 | +/* |
| 3 | + * Copyright (C) 2014 Felix Fietkau <[email protected]> |
| 4 | + * Copyright (C) 2004 - 2009 Ivo van Doorn <[email protected]> |
| 5 | + */ |
| 6 | + |
| 7 | +#ifndef _LINUX_BITFIELD_H |
| 8 | +#define _LINUX_BITFIELD_H |
| 9 | + |
| 10 | +#include <linux/build_bug.h> |
| 11 | +#include <asm/byteorder.h> |
| 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 | + |
| 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 | + |
| 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"); \ |
| 64 | + BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \ |
| 65 | + BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ |
| 66 | + ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \ |
| 67 | + _pfx "value too large for the field"); \ |
| 68 | + BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \ |
| 69 | + __bf_cast_unsigned(_reg, ~0ull), \ |
| 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 | + |
| 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 | + |
| 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 | + ({ \ |
| 97 | + __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \ |
| 98 | + !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \ |
| 99 | + }) |
| 100 | + |
| 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 |
| 118 | + * @_reg: value of entire bitfield |
| 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 | + |
| 129 | +extern void __compiletime_error("value doesn't fit into mask") |
| 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 | +} |
| 143 | +#define field_max(field) ((typeof(field))field_mask(field)) |
| 144 | +#define ____MAKE_OP(type,base,to,from) \ |
| 145 | +static __always_inline __##type type##_encode_bits(base v, base field) \ |
| 146 | +{ \ |
| 147 | + if (__builtin_constant_p(v) && (v & ~field_mask(field))) \ |
| 148 | + __field_overflow(); \ |
| 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,,) |
| 169 | +____MAKE_OP(u8,u8,,) |
| 170 | +__MAKE_OP(16) |
| 171 | +__MAKE_OP(32) |
| 172 | +__MAKE_OP(64) |
| 173 | +#undef __MAKE_OP |
| 174 | +#undef ____MAKE_OP |
| 175 | + |
| 176 | +#endif |
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