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1#ifndef _ASM_WORD_AT_A_TIME_H
2#define _ASM_WORD_AT_A_TIME_H
3
4#include <linux/kernel.h>
5#include <asm/byteorder.h>
6
7#ifdef __BIG_ENDIAN
8
9struct 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 */
16static 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
24static 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
40static 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
47#ifndef zero_bytemask
48#define zero_bytemask(mask) (~1ul << __fls(mask))
49#endif
50
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 */
59struct 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 */
73static 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 */
81static 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 */
92static 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
99static 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
104static 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
113static inline unsigned long find_zero(unsigned long mask)
114{
115 return count_masked_bytes(mask);
116}
117
118#endif /* __BIG_ENDIAN */
119
120#endif /* _ASM_WORD_AT_A_TIME_H */