[linux-block.git] / include / linux / bitfield.h

/* 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:
 *
 *  #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:
 *  reg &= ~REG_FIELD_C;
 *  reg |= FIELD_PREP(REG_FIELD_C, c);
 */

#define __bf_shf(x) (__builtin_ffsll(x) - 1)

#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, _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(__bf_cast_unsigned(_mask, _mask) >	\
				 __bf_cast_unsigned(_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
Commit	Line	Data
1802d0be	1	/* SPDX-License-Identifier: GPL-2.0-only */
3e9b3112 JK	2	/*
	3	* Copyright (C) 2014 Felix Fietkau <nbd@nbd.name>
	4	* Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
3e9b3112 JK	5	*/
	6
	7	#ifndef _LINUX_BITFIELD_H
	8	#define _LINUX_BITFIELD_H
	9
8001541c	10	#include <linux/build_bug.h>
00b0c9b8	11	#include <asm/byteorder.h>
3e9b3112 JK	12
	13	/*
	14	* Bitfield access macros
	15	*
	16	* FIELD_{GET,PREP} macros take as first parameter shifted mask
	17	* from which they extract the base mask and shift amount.
	18	* Mask must be a compilation time constant.
	19	*
	20	* Example:
	21	*
25cb5b7a AS	22	* #include <linux/bitfield.h>
	23	* #include <linux/bits.h>
	24	*
3e9b3112 JK	25	* #define REG_FIELD_A GENMASK(6, 0)
	26	* #define REG_FIELD_B BIT(7)
	27	* #define REG_FIELD_C GENMASK(15, 8)
	28	* #define REG_FIELD_D GENMASK(31, 16)
	29	*
	30	* Get:
	31	* a = FIELD_GET(REG_FIELD_A, reg);
	32	* b = FIELD_GET(REG_FIELD_B, reg);
	33	*
	34	* Set:
	35	* reg = FIELD_PREP(REG_FIELD_A, 1) \|
	36	* FIELD_PREP(REG_FIELD_B, 0) \|
	37	* FIELD_PREP(REG_FIELD_C, c) \|
	38	* FIELD_PREP(REG_FIELD_D, 0x40);
	39	*
	40	* Modify:
	41	* reg &= ~REG_FIELD_C;
	42	* reg \|= FIELD_PREP(REG_FIELD_C, c);
	43	*/
	44
	45	#define __bf_shf(x) (__builtin_ffsll(x) - 1)
	46
bff8c384 PZ	47	#define __scalar_type_to_unsigned_cases(type) \
	48	unsigned type: (unsigned type)0, \
	49	signed type: (unsigned type)0
	50
	51	#define __unsigned_scalar_typeof(x) typeof( \
	52	_Generic((x), \
	53	char: (unsigned char)0, \
	54	__scalar_type_to_unsigned_cases(char), \
	55	__scalar_type_to_unsigned_cases(short), \
	56	__scalar_type_to_unsigned_cases(int), \
	57	__scalar_type_to_unsigned_cases(long), \
	58	__scalar_type_to_unsigned_cases(long long), \
	59	default: (x)))
	60
	61	#define __bf_cast_unsigned(type, x) ((__unsigned_scalar_typeof(type))(x))
	62
3e9b3112 JK	63	#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
	64	({ \
	65	BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \
	66	_pfx "mask is not constant"); \
e36488c8	67	BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \
3e9b3112 JK	68	BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \
	69	~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
	70	_pfx "value too large for the field"); \
bff8c384 PZ	71	BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \
bff8c384 PZ	72	__bf_cast_unsigned(_reg, ~0ull), \
3e9b3112 JK	73	_pfx "type of reg too small for mask"); \
	74	__BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
	75	(1ULL << __bf_shf(_mask))); \
	76	})
	77
e31a5016 AE	78	/**
	79	* FIELD_MAX() - produce the maximum value representable by a field
	80	* @_mask: shifted mask defining the field's length and position
	81	*
	82	* FIELD_MAX() returns the maximum value that can be held in the field
	83	* specified by @_mask.
	84	*/
	85	#define FIELD_MAX(_mask) \
	86	({ \
	87	__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \
	88	(typeof(_mask))((_mask) >> __bf_shf(_mask)); \
	89	})
	90
1697599e JK	91	/**
	92	* FIELD_FIT() - check if value fits in the field
	93	* @_mask: shifted mask defining the field's length and position
	94	* @_val: value to test against the field
	95	*
	96	* Return: true if @_val can fit inside @_mask, false if @_val is too big.
	97	*/
	98	#define FIELD_FIT(_mask, _val) \
	99	({ \
444da3f5	100	__BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \
1697599e JK	101	!((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
	102	})
	103
3e9b3112 JK	104	/**
	105	* FIELD_PREP() - prepare a bitfield element
	106	* @_mask: shifted mask defining the field's length and position
	107	* @_val: value to put in the field
	108	*
	109	* FIELD_PREP() masks and shifts up the value. The result should
	110	* be combined with other fields of the bitfield using logical OR.
	111	*/
	112	#define FIELD_PREP(_mask, _val) \
	113	({ \
	114	__BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \
	115	((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \
	116	})
	117
	118	/**
	119	* FIELD_GET() - extract a bitfield element
	120	* @_mask: shifted mask defining the field's length and position
72407674	121	* @_reg: value of entire bitfield
3e9b3112 JK	122	*
	123	* FIELD_GET() extracts the field specified by @_mask from the
	124	* bitfield passed in as @_reg by masking and shifting it down.
	125	*/
	126	#define FIELD_GET(_mask, _reg) \
	127	({ \
	128	__BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \
	129	(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
	130	})
	131
e7d4a95d	132	extern void __compiletime_error("value doesn't fit into mask")
00b0c9b8 AV	133	__field_overflow(void);
	134	extern void __compiletime_error("bad bitfield mask")
	135	__bad_mask(void);
	136	static __always_inline u64 field_multiplier(u64 field)
	137	{
	138	if ((field \| (field - 1)) & ((field \| (field - 1)) + 1))
	139	__bad_mask();
	140	return field & -field;
	141	}
	142	static __always_inline u64 field_mask(u64 field)
	143	{
	144	return field / field_multiplier(field);
	145	}
e31a5016	146	#define field_max(field) ((typeof(field))field_mask(field))
00b0c9b8 AV	147	#define ____MAKE_OP(type,base,to,from) \
	148	static __always_inline __##type type##_encode_bits(base v, base field) \
	149	{ \
e7d4a95d JB	150	if (__builtin_constant_p(v) && (v & ~field_mask(field))) \
e7d4a95d JB	151	__field_overflow(); \
00b0c9b8 AV	152	return to((v & field_mask(field)) * field_multiplier(field)); \
	153	} \
	154	static __always_inline __##type type##_replace_bits(__##type old, \
	155	base val, base field) \
	156	{ \
	157	return (old & ~to(field)) \| type##_encode_bits(val, field); \
	158	} \
	159	static __always_inline void type##p_replace_bits(__##type *p, \
	160	base val, base field) \
	161	{ \
	162	p = (p & ~to(field)) \| type##_encode_bits(val, field); \
	163	} \
	164	static __always_inline base type##_get_bits(__##type v, base field) \
	165	{ \
	166	return (from(v) & field)/field_multiplier(field); \
	167	}
	168	#define __MAKE_OP(size) \
	169	____MAKE_OP(le##size,u##size,cpu_to_le##size,le##size##_to_cpu) \
	170	____MAKE_OP(be##size,u##size,cpu_to_be##size,be##size##_to_cpu) \
	171	____MAKE_OP(u##size,u##size,,)
37a3862e	172	____MAKE_OP(u8,u8,,)
00b0c9b8 AV	173	__MAKE_OP(16)
	174	__MAKE_OP(32)
	175	__MAKE_OP(64)
	176	#undef __MAKE_OP
	177	#undef ____MAKE_OP
	178
3e9b3112	179	#endif