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159 lines
4.8 KiB
159 lines
4.8 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* |
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* Copyright (C) 2014 Felix Fietkau <[email protected]> |
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* Copyright (C) 2004 - 2009 Ivo van Doorn <[email protected]> |
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*/ |
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#ifndef _LINUX_BITFIELD_H |
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#define _LINUX_BITFIELD_H |
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#include <linux/build_bug.h> |
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#include <asm/byteorder.h> |
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/* |
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* Bitfield access macros |
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* |
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* FIELD_{GET,PREP} macros take as first parameter shifted mask |
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* from which they extract the base mask and shift amount. |
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* Mask must be a compilation time constant. |
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* |
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* Example: |
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* |
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* #define REG_FIELD_A GENMASK(6, 0) |
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* #define REG_FIELD_B BIT(7) |
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* #define REG_FIELD_C GENMASK(15, 8) |
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* #define REG_FIELD_D GENMASK(31, 16) |
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* |
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* Get: |
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* a = FIELD_GET(REG_FIELD_A, reg); |
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* b = FIELD_GET(REG_FIELD_B, reg); |
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* |
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* Set: |
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* reg = FIELD_PREP(REG_FIELD_A, 1) | |
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* FIELD_PREP(REG_FIELD_B, 0) | |
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* FIELD_PREP(REG_FIELD_C, c) | |
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* FIELD_PREP(REG_FIELD_D, 0x40); |
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* |
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* Modify: |
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* reg &= ~REG_FIELD_C; |
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* reg |= FIELD_PREP(REG_FIELD_C, c); |
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*/ |
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#define __bf_shf(x) (__builtin_ffsll(x) - 1) |
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#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \ |
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({ \ |
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BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \ |
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_pfx "mask is not constant"); \ |
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BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \ |
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BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ |
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~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \ |
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_pfx "value too large for the field"); \ |
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BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull, \ |
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_pfx "type of reg too small for mask"); \ |
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__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \ |
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(1ULL << __bf_shf(_mask))); \ |
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}) |
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/** |
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* FIELD_MAX() - produce the maximum value representable by a field |
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* @_mask: shifted mask defining the field's length and position |
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* |
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* FIELD_MAX() returns the maximum value that can be held in the field |
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* specified by @_mask. |
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*/ |
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#define FIELD_MAX(_mask) \ |
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({ \ |
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__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \ |
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(typeof(_mask))((_mask) >> __bf_shf(_mask)); \ |
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}) |
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/** |
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* FIELD_FIT() - check if value fits in the field |
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* @_mask: shifted mask defining the field's length and position |
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* @_val: value to test against the field |
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* |
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* Return: true if @_val can fit inside @_mask, false if @_val is too big. |
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*/ |
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#define FIELD_FIT(_mask, _val) \ |
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({ \ |
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__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \ |
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!((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \ |
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}) |
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/** |
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* FIELD_PREP() - prepare a bitfield element |
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* @_mask: shifted mask defining the field's length and position |
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* @_val: value to put in the field |
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* |
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* FIELD_PREP() masks and shifts up the value. The result should |
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* be combined with other fields of the bitfield using logical OR. |
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*/ |
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#define FIELD_PREP(_mask, _val) \ |
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({ \ |
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__BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \ |
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((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \ |
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}) |
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/** |
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* FIELD_GET() - extract a bitfield element |
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* @_mask: shifted mask defining the field's length and position |
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* @_reg: value of entire bitfield |
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* |
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* FIELD_GET() extracts the field specified by @_mask from the |
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* bitfield passed in as @_reg by masking and shifting it down. |
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*/ |
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#define FIELD_GET(_mask, _reg) \ |
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({ \ |
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__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \ |
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(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \ |
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}) |
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extern void __compiletime_error("value doesn't fit into mask") |
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__field_overflow(void); |
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extern void __compiletime_error("bad bitfield mask") |
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__bad_mask(void); |
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static __always_inline u64 field_multiplier(u64 field) |
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{ |
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if ((field | (field - 1)) & ((field | (field - 1)) + 1)) |
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__bad_mask(); |
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return field & -field; |
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} |
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static __always_inline u64 field_mask(u64 field) |
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{ |
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return field / field_multiplier(field); |
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} |
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#define field_max(field) ((typeof(field))field_mask(field)) |
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#define ____MAKE_OP(type,base,to,from) \ |
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static __always_inline __##type type##_encode_bits(base v, base field) \ |
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{ \ |
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if (__builtin_constant_p(v) && (v & ~field_mask(field))) \ |
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__field_overflow(); \ |
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return to((v & field_mask(field)) * field_multiplier(field)); \ |
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} \ |
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static __always_inline __##type type##_replace_bits(__##type old, \ |
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base val, base field) \ |
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{ \ |
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return (old & ~to(field)) | type##_encode_bits(val, field); \ |
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} \ |
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static __always_inline void type##p_replace_bits(__##type *p, \ |
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base val, base field) \ |
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{ \ |
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*p = (*p & ~to(field)) | type##_encode_bits(val, field); \ |
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} \ |
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static __always_inline base type##_get_bits(__##type v, base field) \ |
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{ \ |
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return (from(v) & field)/field_multiplier(field); \ |
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} |
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#define __MAKE_OP(size) \ |
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____MAKE_OP(le##size,u##size,cpu_to_le##size,le##size##_to_cpu) \ |
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____MAKE_OP(be##size,u##size,cpu_to_be##size,be##size##_to_cpu) \ |
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____MAKE_OP(u##size,u##size,,) |
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____MAKE_OP(u8,u8,,) |
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__MAKE_OP(16) |
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__MAKE_OP(32) |
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__MAKE_OP(64) |
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#undef __MAKE_OP |
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#undef ____MAKE_OP |
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#endif
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