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/kernel.h>
6 #include <asm/byteorder.h>
7
8 #ifdef __BIG_ENDIAN
9
10 struct word_at_a_time {
11 const unsigned long high_bits, low_bits;
12 };
13
14 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
15
16 /* Bit set in the bytes that have a zero */
prep_zero_mask(unsigned long val,unsigned long rhs,const struct word_at_a_time * c)17 static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
18 {
19 unsigned long mask = (val & c->low_bits) + c->low_bits;
20 return ~(mask | rhs);
21 }
22
23 #define create_zero_mask(mask) (mask)
24
find_zero(unsigned long mask)25 static inline long find_zero(unsigned long mask)
26 {
27 long byte = 0;
28 #ifdef CONFIG_64BIT
29 if (mask >> 32)
30 mask >>= 32;
31 else
32 byte = 4;
33 #endif
34 if (mask >> 16)
35 mask >>= 16;
36 else
37 byte += 2;
38 return (mask >> 8) ? byte : byte + 1;
39 }
40
has_zero(unsigned long val,unsigned long * data,const struct word_at_a_time * c)41 static inline unsigned long has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
42 {
43 unsigned long rhs = val | c->low_bits;
44 *data = rhs;
45 return (val + c->high_bits) & ~rhs;
46 }
47
48 #ifndef zero_bytemask
49 #define zero_bytemask(mask) (~1ul << __fls(mask))
50 #endif
51
52 #else
53
54 /*
55 * The optimal byte mask counting is probably going to be something
56 * that is architecture-specific. If you have a reliably fast
57 * bit count instruction, that might be better than the multiply
58 * and shift, for example.
59 */
60 struct word_at_a_time {
61 const unsigned long one_bits, high_bits;
62 };
63
64 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
65
66 #ifdef CONFIG_64BIT
67
68 /*
69 * Jan Achrenius on G+: microoptimized version of
70 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
71 * that works for the bytemasks without having to
72 * mask them first.
73 */
count_masked_bytes(unsigned long mask)74 static inline long count_masked_bytes(unsigned long mask)
75 {
76 return mask*0x0001020304050608ul >> 56;
77 }
78
79 #else /* 32-bit case */
80
81 /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
count_masked_bytes(long mask)82 static inline long count_masked_bytes(long mask)
83 {
84 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
85 long a = (0x0ff0001+mask) >> 23;
86 /* Fix the 1 for 00 case */
87 return a & mask;
88 }
89
90 #endif
91
92 /* Return nonzero if it has a zero */
has_zero(unsigned long a,unsigned long * bits,const struct word_at_a_time * c)93 static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
94 {
95 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
96 *bits = mask;
97 return mask;
98 }
99
prep_zero_mask(unsigned long a,unsigned long bits,const struct word_at_a_time * c)100 static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
101 {
102 return bits;
103 }
104
create_zero_mask(unsigned long bits)105 static inline unsigned long create_zero_mask(unsigned long bits)
106 {
107 bits = (bits - 1) & ~bits;
108 return bits >> 7;
109 }
110
111 /* The mask we created is directly usable as a bytemask */
112 #define zero_bytemask(mask) (mask)
113
find_zero(unsigned long mask)114 static inline unsigned long find_zero(unsigned long mask)
115 {
116 return count_masked_bytes(mask);
117 }
118
119 #endif /* __BIG_ENDIAN */
120
121 #endif /* _ASM_WORD_AT_A_TIME_H */
122
