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1/* SPDX-License-Identifier: GPL-2.0-only */2/*3 * Copyright (C) 2014 Felix Fietkau <nbd@nbd.name>4 * Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>5 */6 7#ifndef _LINUX_BITFIELD_H8#define _LINUX_BITFIELD_H9 10#include <linux/build_bug.h>11#include <asm/byteorder.h>12 13/*14 * Bitfield access macros15 *16 * FIELD_{GET,PREP} macros take as first parameter shifted mask17 * 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)047 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 field77 * @_mask: shifted mask defining the field's length and position78 *79 * FIELD_MAX() returns the maximum value that can be held in the field80 * 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 field90 * @_mask: shifted mask defining the field's length and position91 * @_val: value to test against the field92 *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 element103 * @_mask: shifted mask defining the field's length and position104 * @_val: value to put in the field105 *106 * FIELD_PREP() masks and shifts up the value. The result should107 * 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 element117 * @_mask: shifted mask defining the field's length and position118 * @_reg: value of entire bitfield119 *120 * FIELD_GET() extracts the field specified by @_mask from the121 * 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 129extern void __compiletime_error("value doesn't fit into mask")130__field_overflow(void);131extern void __compiletime_error("bad bitfield mask")132__bad_mask(void);133static __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}139static __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) \145static __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} \151static __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} \156static __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} \161static __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_OP174#undef ____MAKE_OP175 176#endif177