diff options
Diffstat (limited to 'include/linux/bitfield.h')
| -rw-r--r-- | include/linux/bitfield.h | 103 |
1 files changed, 75 insertions, 28 deletions
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h index 7ad02f8cbb9..63928f17322 100644 --- a/include/linux/bitfield.h +++ b/include/linux/bitfield.h @@ -1,21 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ /* * 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/bug.h> +#include <linux/build_bug.h> #include <asm/byteorder.h> /* @@ -27,6 +19,9 @@ * * Example: * + * #include <linux/bitfield.h> + * #include <linux/bits.h> + * * #define REG_FIELD_A GENMASK(6, 0) * #define REG_FIELD_B BIT(7) * #define REG_FIELD_C GENMASK(15, 8) @@ -49,21 +44,52 @@ #define __bf_shf(x) (__builtin_ffsll(x) - 1) +#define __scalar_type_to_unsigned_cases(type) \ + unsigned type: (unsigned type)0, \ + signed type: (unsigned type)0 + +#define __unsigned_scalar_typeof(x) typeof( \ + _Generic((x), \ + char: (unsigned char)0, \ + __scalar_type_to_unsigned_cases(char), \ + __scalar_type_to_unsigned_cases(short), \ + __scalar_type_to_unsigned_cases(int), \ + __scalar_type_to_unsigned_cases(long), \ + __scalar_type_to_unsigned_cases(long long), \ + default: (x))) + +#define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x)) + #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((_mask) == 0, _pfx "mask is zero"); \ BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ - ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \ + ~((_mask) >> __bf_shf(_mask)) & \ + (0 + (_val)) : 0, \ _pfx "value too large for the field"); \ - BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull, \ + BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \ + __bf_cast_unsigned(_reg, ~0ull), \ _pfx "type of reg too small for mask"); \ __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \ (1ULL << __bf_shf(_mask))); \ }) /** + * FIELD_MAX() - produce the maximum value representable by a field + * @_mask: shifted mask defining the field's length and position + * + * FIELD_MAX() returns the maximum value that can be held in the field + * specified by @_mask. + */ +#define FIELD_MAX(_mask) \ + ({ \ + __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \ + (typeof(_mask))((_mask) >> __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 @@ -72,7 +98,7 @@ */ #define FIELD_FIT(_mask, _val) \ ({ \ - __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_FIT: "); \ + __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \ !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \ }) @@ -90,10 +116,36 @@ ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \ }) +#define __BF_CHECK_POW2(n) BUILD_BUG_ON_ZERO(((n) & ((n) - 1)) != 0) + +/** + * FIELD_PREP_CONST() - prepare a constant bitfield element + * @_mask: shifted mask defining the field's length and position + * @_val: value to put in the field + * + * FIELD_PREP_CONST() masks and shifts up the value. The result should + * be combined with other fields of the bitfield using logical OR. + * + * Unlike FIELD_PREP() this is a constant expression and can therefore + * be used in initializers. Error checking is less comfortable for this + * version, and non-constant masks cannot be used. + */ +#define FIELD_PREP_CONST(_mask, _val) \ + ( \ + /* mask must be non-zero */ \ + BUILD_BUG_ON_ZERO((_mask) == 0) + \ + /* check if value fits */ \ + BUILD_BUG_ON_ZERO(~((_mask) >> __bf_shf(_mask)) & (_val)) + \ + /* check if mask is contiguous */ \ + __BF_CHECK_POW2((_mask) + (1ULL << __bf_shf(_mask))) + \ + /* and create the value */ \ + (((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask)) \ + ) + /** * FIELD_GET() - extract a bitfield element * @_mask: shifted mask defining the field's length and position - * @_reg: 32bit value of entire bitfield + * @_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. @@ -108,20 +160,18 @@ 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) \ +#define field_max(field) ((typeof(field))field_mask(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))) \ @@ -133,26 +183,23 @@ static __always_inline __##type type##_replace_bits(__##type old, \ { \ return (old & ~to(field)) | type##_encode_bits(val, field); \ } \ -static __always_inline void type##p_replace_bits(__##type * p, \ +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); \ + 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(u8, u8, ,) + ____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(u8,u8,,) __MAKE_OP(16) __MAKE_OP(32) __MAKE_OP(64) - #undef __MAKE_OP #undef ____MAKE_OP |