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106 lines
3.2 KiB
106 lines
3.2 KiB
/* |
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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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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License version 2 |
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* as published by the Free Software Foundation |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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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/bug.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), _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_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, _val, "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: 32bit 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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#endif
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