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
11 struct 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 */
18 static 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
26 static 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
42 static 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 */
61 struct 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 */
75 static 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 */
83 static 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 */
94 static 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
101 static 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
106 static 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
115 static 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
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