| /* 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> |
| */ |
| |
| #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) == 0, _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_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 |
| * |
| * Return: true if @_val can fit inside @_mask, false if @_val is too big. |
| */ |
| #define FIELD_FIT(_mask, _val) \ |
| ({ \ |
| __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "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 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))) \ |
| __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(u8,u8,,) |
| __MAKE_OP(16) |
| __MAKE_OP(32) |
| __MAKE_OP(64) |
| #undef __MAKE_OP |
| #undef ____MAKE_OP |
| |
| #endif |