1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_WORD_AT_A_TIME_H
3 #define _ASM_WORD_AT_A_TIME_H
5 #include <linux/kernel.h>
6 #include <asm/byteorder.h>
10 struct word_at_a_time {
11 const unsigned long high_bits, low_bits;
14 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
16 /* Bit set in the bytes that have a zero */
17 static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
19 unsigned long mask = (val & c->low_bits) + c->low_bits;
23 #define create_zero_mask(mask) (mask)
25 static inline long find_zero(unsigned long mask)
38 return (mask >> 8) ? byte : byte + 1;
41 static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
43 unsigned long rhs = val | c->low_bits;
45 return (val + c->high_bits) & ~rhs;
49 #define zero_bytemask(mask) (~1ul << __fls(mask))
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.
60 struct word_at_a_time {
61 const unsigned long one_bits, high_bits;
64 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
69 * Jan Achrenius on G+: microoptimized version of
70 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
71 * that works for the bytemasks without having to
74 static inline long count_masked_bytes(unsigned long mask)
76 return mask*0x0001020304050608ul >> 56;
79 #else /* 32-bit case */
81 /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
82 static inline long count_masked_bytes(long mask)
84 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
85 long a = (0x0ff0001+mask) >> 23;
86 /* Fix the 1 for 00 case */
92 /* Return nonzero if it has a zero */
93 static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
95 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
100 static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
105 static inline unsigned long create_zero_mask(unsigned long bits)
107 bits = (bits - 1) & ~bits;
111 /* The mask we created is directly usable as a bytemask */
112 #define zero_bytemask(mask) (mask)
114 static inline unsigned long find_zero(unsigned long mask)
116 return count_masked_bytes(mask);
119 #endif /* __BIG_ENDIAN */
121 #endif /* _ASM_WORD_AT_A_TIME_H */