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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#ifndef _LINUX_BITFIELD_H#define _LINUX_BITFIELD_H
#include <linux/build_bug.h>#include <linux/compiler.h>#include <linux/typecheck.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. * field_{get,prep} are variants that take a non-const mask. * * 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) * #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: * FIELD_MODIFY(REG_FIELD_C, ®, c); */
#define __bf_shf __builtin_ctzll
#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(_mask, _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)) & \ (0 + (_val)) : 0, \ _pfx "value too large for the field"); \ __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \ (1ULL << __bf_shf(_mask))); \ })
#define __BF_FIELD_CHECK_REG(mask, reg, pfx) \ BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) > \ __bf_cast_unsigned(reg, ~0ull), \ pfx "type of reg too small for mask")
#define __BF_FIELD_CHECK(mask, reg, val, pfx) \ ({ \ __BF_FIELD_CHECK_MASK(mask, val, pfx); \ __BF_FIELD_CHECK_REG(mask, reg, pfx); \ })
#define __FIELD_PREP(mask, val, pfx) \ ({ \ __BF_FIELD_CHECK_MASK(mask, val, pfx); \ ((typeof(mask))(val) << __bf_shf(mask)) & (mask); \ })
#define __FIELD_GET(mask, reg, pfx) \ ({ \ __BF_FIELD_CHECK_MASK(mask, 0U, pfx); \ (typeof(mask))(((reg) & (mask)) >> __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_REG(_mask, 0ULL, "FIELD_PREP: "); \ __FIELD_PREP(_mask, _val, "FIELD_PREP: "); \ })
#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: 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_REG(_mask, _reg, "FIELD_GET: "); \ __FIELD_GET(_mask, _reg, "FIELD_GET: "); \ })
/** * FIELD_GET_SIGNED() - extract a signed bitfield element * @mask: shifted mask defining the field's length and position * @reg: value of entire bitfield * * Returns the sign-extended field specified by @_mask from the * bitfield passed in as @reg by masking and shifting it down. */#define FIELD_GET_SIGNED(mask, reg) \ ({ \ __BF_FIELD_CHECK(mask, reg, 0U, "FIELD_GET_SIGNED: "); \ ((__signed_scalar_typeof(mask)) \ (((long long)(reg) << __builtin_clzll(mask)) >> \ (__builtin_clzll(mask) + __builtin_ctzll(mask)))); \ })
/** * FIELD_MODIFY() - modify a bitfield element * @_mask: shifted mask defining the field's length and position * @_reg_p: pointer to the memory that should be updated * @_val: value to store in the bitfield * * FIELD_MODIFY() modifies the set of bits in @_reg_p specified by @_mask, * by replacing them with the bitfield value passed in as @_val. */#define FIELD_MODIFY(_mask, _reg_p, _val) \ ({ \ typecheck_pointer(_reg_p); \ __BF_FIELD_CHECK(_mask, *(_reg_p), _val, "FIELD_MODIFY: "); \ *(_reg_p) &= ~(_mask); \ *(_reg_p) |= (((typeof(_mask))(_val) << __bf_shf(_mask)) & (_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 __must_check 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 __must_check 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 __must_check 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
#define __field_prep(mask, val) \ ({ \ auto __mask = (mask); \ typeof(__mask) __val = (val); \ unsigned int __shift = BITS_PER_TYPE(__mask) <= 32 ? \ __ffs(__mask) : __ffs64(__mask); \ (__val << __shift) & __mask; \ })
#define __field_get(mask, reg) \ ({ \ auto __mask = (mask); \ typeof(__mask) __reg = (reg); \ unsigned int __shift = BITS_PER_TYPE(__mask) <= 32 ? \ __ffs(__mask) : __ffs64(__mask); \ (__reg & __mask) >> __shift; \ })
/** * field_prep() - prepare a bitfield element * @mask: shifted mask defining the field's length and position, must be * non-zero * @val: value to put in the field * * Return: field value masked and shifted to its final destination * * field_prep() masks and shifts up the value. The result should be * combined with other fields of the bitfield using logical OR. * Unlike FIELD_PREP(), @mask is not limited to a compile-time constant. * Typical usage patterns are a value stored in a table, or calculated by * shifting a constant by a variable number of bits. * If you want to ensure that @mask is a compile-time constant, please use * FIELD_PREP() directly instead. */#define field_prep(mask, val) \ (__builtin_constant_p(mask) ? __FIELD_PREP(mask, val, "field_prep: ") \ : __field_prep(mask, val))
/** * field_get() - extract a bitfield element * @mask: shifted mask defining the field's length and position, must be * non-zero * @reg: value of entire bitfield * * Return: extracted field value * * field_get() extracts the field specified by @mask from the * bitfield passed in as @reg by masking and shifting it down. * Unlike FIELD_GET(), @mask is not limited to a compile-time constant. * Typical usage patterns are a value stored in a table, or calculated by * shifting a constant by a variable number of bits. * If you want to ensure that @mask is a compile-time constant, please use * FIELD_GET() directly instead. */#define field_get(mask, reg) \ (__builtin_constant_p(mask) ? __FIELD_GET(mask, reg, "field_get: ") \ : __field_get(mask, reg))
#endif