[linux.git] / include / asm-generic / word-at-a-time.h

#ifndef _ASM_WORD_AT_A_TIME_H
#define _ASM_WORD_AT_A_TIME_H

#include <linux/kernel.h>
#include <asm/byteorder.h>

#ifdef __BIG_ENDIAN

struct word_at_a_time {
	const unsigned long high_bits, low_bits;
};

#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }

/* Bit set in the bytes that have a zero */
static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
{
	unsigned long mask = (val & c->low_bits) + c->low_bits;
	return ~(mask | rhs);
}

#define create_zero_mask(mask) (mask)

static inline long find_zero(unsigned long mask)
{
	long byte = 0;
#ifdef CONFIG_64BIT
	if (mask >> 32)
		mask >>= 32;
	else
		byte = 4;
#endif
	if (mask >> 16)
		mask >>= 16;
	else
		byte += 2;
	return (mask >> 8) ? byte : byte + 1;
}

static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
{
	unsigned long rhs = val | c->low_bits;
	*data = rhs;
	return (val + c->high_bits) & ~rhs;
}

#ifndef zero_bytemask
#define zero_bytemask(mask) (~1ul << __fls(mask))
#endif

#else

/*
 * The optimal byte mask counting is probably going to be something
 * that is architecture-specific. If you have a reliably fast
 * bit count instruction, that might be better than the multiply
 * and shift, for example.
 */
struct word_at_a_time {
	const unsigned long one_bits, high_bits;
};

#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }

#ifdef CONFIG_64BIT

/*
 * Jan Achrenius on G+: microoptimized version of
 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
 * that works for the bytemasks without having to
 * mask them first.
 */
static inline long count_masked_bytes(unsigned long mask)
{
	return mask*0x0001020304050608ul >> 56;
}

#else	/* 32-bit case */

/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
static inline long count_masked_bytes(long mask)
{
	/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
	long a = (0x0ff0001+mask) >> 23;
	/* Fix the 1 for 00 case */
	return a & mask;
}

#endif

/* Return nonzero if it has a zero */
static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
{
	unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
	*bits = mask;
	return mask;
}

static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
{
	return bits;
}

static inline unsigned long create_zero_mask(unsigned long bits)
{
	bits = (bits - 1) & ~bits;
	return bits >> 7;
}

/* The mask we created is directly usable as a bytemask */
#define zero_bytemask(mask) (mask)

static inline unsigned long find_zero(unsigned long mask)
{
	return count_masked_bytes(mask);
}

#endif /* __BIG_ENDIAN */

#endif /* _ASM_WORD_AT_A_TIME_H */
Commit	Line	Data
36126f8f LT	1	#ifndef _ASM_WORD_AT_A_TIME_H
	2	#define _ASM_WORD_AT_A_TIME_H
	3
36126f8f	4	#include <linux/kernel.h>
a6e2f029 CM	5	#include <asm/byteorder.h>
	6
	7	#ifdef __BIG_ENDIAN
36126f8f LT	8
	9	struct word_at_a_time {
	10	const unsigned long high_bits, low_bits;
	11	};
	12
	13	#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
	14
	15	/* Bit set in the bytes that have a zero */
	16	static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
	17	{
	18	unsigned long mask = (val & c->low_bits) + c->low_bits;
	19	return ~(mask \| rhs);
	20	}
	21
	22	#define create_zero_mask(mask) (mask)
	23
	24	static inline long find_zero(unsigned long mask)
	25	{
	26	long byte = 0;
	27	#ifdef CONFIG_64BIT
	28	if (mask >> 32)
	29	mask >>= 32;
	30	else
	31	byte = 4;
	32	#endif
	33	if (mask >> 16)
	34	mask >>= 16;
	35	else
	36	byte += 2;
	37	return (mask >> 8) ? byte : byte + 1;
	38	}
	39
	40	static inline bool has_zero(unsigned long val, unsigned long data, const struct word_at_a_time c)
	41	{
	42	unsigned long rhs = val \| c->low_bits;
	43	*data = rhs;
	44	return (val + c->high_bits) & ~rhs;
	45	}
	46
11ec50ca	47	#ifndef zero_bytemask
789ce9dc	48	#define zero_bytemask(mask) (~1ul << __fls(mask))
ec6931b2	49	#endif
11ec50ca	50
a6e2f029 CM	51	#else
	52
	53	/*
	54	* The optimal byte mask counting is probably going to be something
	55	* that is architecture-specific. If you have a reliably fast
	56	* bit count instruction, that might be better than the multiply
	57	* and shift, for example.
	58	*/
	59	struct word_at_a_time {
	60	const unsigned long one_bits, high_bits;
	61	};
	62
	63	#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
	64
	65	#ifdef CONFIG_64BIT
	66
	67	/*
	68	* Jan Achrenius on G+: microoptimized version of
	69	* the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
	70	* that works for the bytemasks without having to
	71	* mask them first.
	72	*/
	73	static inline long count_masked_bytes(unsigned long mask)
	74	{
	75	return mask*0x0001020304050608ul >> 56;
	76	}
	77
	78	#else /* 32-bit case */
	79
	80	/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
	81	static inline long count_masked_bytes(long mask)
	82	{
	83	/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
	84	long a = (0x0ff0001+mask) >> 23;
	85	/* Fix the 1 for 00 case */
	86	return a & mask;
	87	}
	88
	89	#endif
	90
	91	/* Return nonzero if it has a zero */
	92	static inline unsigned long has_zero(unsigned long a, unsigned long bits, const struct word_at_a_time c)
	93	{
	94	unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
	95	*bits = mask;
	96	return mask;
	97	}
	98
	99	static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
	100	{
	101	return bits;
	102	}
	103
	104	static inline unsigned long create_zero_mask(unsigned long bits)
	105	{
	106	bits = (bits - 1) & ~bits;
	107	return bits >> 7;
	108	}
	109
	110	/* The mask we created is directly usable as a bytemask */
	111	#define zero_bytemask(mask) (mask)
	112
	113	static inline unsigned long find_zero(unsigned long mask)
	114	{
115	return count_masked_bytes(mask);
116	}
117
118	#endif /* __BIG_ENDIAN */
119
36126f8f	120	#endif /* _ASM_WORD_AT_A_TIME_H */