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 
9 struct 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 */
16 static 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 
24 static 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 
40 static 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  */
59 struct 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  */
73 static 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 */
81 static 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 */
92 static 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 
99 static 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 
104 static 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 
113 static 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 */
121