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 */
123