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Linus Torvalds36126f82012-05-26 10:43:17 -07001#ifndef _ASM_WORD_AT_A_TIME_H
2#define _ASM_WORD_AT_A_TIME_H
3
4/*
5 * This says "generic", but it's actually big-endian only.
6 * Little-endian can use more efficient versions of these
7 * interfaces, see for example
8 * arch/x86/include/asm/word-at-a-time.h
9 * for those.
10 */
11
12#include <linux/kernel.h>
13
14struct word_at_a_time {
15 const unsigned long high_bits, low_bits;
16};
17
18#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
19
20/* Bit set in the bytes that have a zero */
21static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
22{
23 unsigned long mask = (val & c->low_bits) + c->low_bits;
24 return ~(mask | rhs);
25}
26
27#define create_zero_mask(mask) (mask)
28
29static inline long find_zero(unsigned long mask)
30{
31 long byte = 0;
32#ifdef CONFIG_64BIT
33 if (mask >> 32)
34 mask >>= 32;
35 else
36 byte = 4;
37#endif
38 if (mask >> 16)
39 mask >>= 16;
40 else
41 byte += 2;
42 return (mask >> 8) ? byte : byte + 1;
43}
44
45static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
46{
47 unsigned long rhs = val | c->low_bits;
48 *data = rhs;
49 return (val + c->high_bits) & ~rhs;
50}
51
Will Deacon11ec50c2013-12-12 17:40:22 +000052#ifndef zero_bytemask
H. Peter Anvin789ce9d2014-04-30 14:22:19 -070053#define zero_bytemask(mask) (~1ul << __fls(mask))
Will Deaconec6931b2014-04-23 17:52:52 +010054#endif
Will Deacon11ec50c2013-12-12 17:40:22 +000055
Linus Torvalds36126f82012-05-26 10:43:17 -070056#endif /* _ASM_WORD_AT_A_TIME_H */