1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef _ASM_WORD_AT_A_TIME_H
  3#define _ASM_WORD_AT_A_TIME_H
  4
  5#include <linux/bitops.h>
  6#include <linux/wordpart.h>
  7#include <asm/byteorder.h>
  8
  9#ifdef __BIG_ENDIAN
 10
 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_64BIT
 30	if (mask >> 32)
 31		mask >>= 32;
 32	else
 33		byte = 4;
 34#endif
 35	if (mask >> 16)
 36		mask >>= 16;
 37	else
 38		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_bytemask
 50#define zero_bytemask(mask) (~1ul << __fls(mask))
 51#endif
 52
 53#else
 54
 55/*
 56 * The optimal byte mask counting is probably going to be something
 57 * that is architecture-specific. If you have a reliably fast
 58 * bit count instruction, that might be better than the multiply
 59 * 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_64BIT
 68
 69/*
 70 * Jan Achrenius on G+: microoptimized version of
 71 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
 72 * that works for the bytemasks without having to
 73 * 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#endif
 92
 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 */