123 lines · c
1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _ASM_WORD_AT_A_TIME_H3#define _ASM_WORD_AT_A_TIME_H4 5#include <linux/bitops.h>6#include <linux/wordpart.h>7#include <asm/byteorder.h>8 9#ifdef __BIG_ENDIAN10 11struct word_at_a_time {12 const unsigned long high_bits, low_bits;13};14 15#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }16 17/* Bit set in the bytes that have a zero */18static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)19{20 unsigned long mask = (val & c->low_bits) + c->low_bits;21 return ~(mask | rhs);22}23 24#define create_zero_mask(mask) (mask)25 26static inline long find_zero(unsigned long mask)27{28 long byte = 0;29#ifdef CONFIG_64BIT30 if (mask >> 32)31 mask >>= 32;32 else33 byte = 4;34#endif35 if (mask >> 16)36 mask >>= 16;37 else38 byte += 2;39 return (mask >> 8) ? byte : byte + 1;40}41 42static inline unsigned long has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)43{44 unsigned long rhs = val | c->low_bits;45 *data = rhs;46 return (val + c->high_bits) & ~rhs;47}48 49#ifndef zero_bytemask50#define zero_bytemask(mask) (~1ul << __fls(mask))51#endif52 53#else54 55/*56 * The optimal byte mask counting is probably going to be something57 * that is architecture-specific. If you have a reliably fast58 * bit count instruction, that might be better than the multiply59 * and shift, for example.60 */61struct word_at_a_time {62 const unsigned long one_bits, high_bits;63};64 65#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }66 67#ifdef CONFIG_64BIT68 69/*70 * Jan Achrenius on G+: microoptimized version of71 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"72 * that works for the bytemasks without having to73 * mask them first.74 */75static inline long count_masked_bytes(unsigned long mask)76{77 return mask*0x0001020304050608ul >> 56;78}79 80#else /* 32-bit case */81 82/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */83static inline long count_masked_bytes(long mask)84{85 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */86 long a = (0x0ff0001+mask) >> 23;87 /* Fix the 1 for 00 case */88 return a & mask;89}90 91#endif92 93/* Return nonzero if it has a zero */94static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)95{96 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;97 *bits = mask;98 return mask;99}100 101static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)102{103 return bits;104}105 106static inline unsigned long create_zero_mask(unsigned long bits)107{108 bits = (bits - 1) & ~bits;109 return bits >> 7;110}111 112/* The mask we created is directly usable as a bytemask */113#define zero_bytemask(mask) (mask)114 115static inline unsigned long find_zero(unsigned long mask)116{117 return count_masked_bytes(mask);118}119 120#endif /* __BIG_ENDIAN */121 122#endif /* _ASM_WORD_AT_A_TIME_H */123