1 /*
2  * Copyright (c) 2000,2002,2005 Silicon Graphics, Inc.
3  * All Rights Reserved.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it would be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write the Free Software Foundation,
16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17  */
18 #ifndef __XFS_BIT_H__
19 #define	__XFS_BIT_H__
20 
21 /*
22  * XFS bit manipulation routines.
23  */
24 
25 /*
26  * masks with n high/low bits set, 64-bit values
27  */
xfs_mask64hi(int n)28 static inline __uint64_t xfs_mask64hi(int n)
29 {
30 	return (__uint64_t)-1 << (64 - (n));
31 }
xfs_mask32lo(int n)32 static inline __uint32_t xfs_mask32lo(int n)
33 {
34 	return ((__uint32_t)1 << (n)) - 1;
35 }
xfs_mask64lo(int n)36 static inline __uint64_t xfs_mask64lo(int n)
37 {
38 	return ((__uint64_t)1 << (n)) - 1;
39 }
40 
41 /* Get high bit set out of 32-bit argument, -1 if none set */
xfs_highbit32(__uint32_t v)42 static inline int xfs_highbit32(__uint32_t v)
43 {
44 	return fls(v) - 1;
45 }
46 
47 /* Get high bit set out of 64-bit argument, -1 if none set */
xfs_highbit64(__uint64_t v)48 static inline int xfs_highbit64(__uint64_t v)
49 {
50 	return fls64(v) - 1;
51 }
52 
53 /* Get low bit set out of 32-bit argument, -1 if none set */
xfs_lowbit32(__uint32_t v)54 static inline int xfs_lowbit32(__uint32_t v)
55 {
56 	return ffs(v) - 1;
57 }
58 
59 /* Get low bit set out of 64-bit argument, -1 if none set */
xfs_lowbit64(__uint64_t v)60 static inline int xfs_lowbit64(__uint64_t v)
61 {
62 	__uint32_t	w = (__uint32_t)v;
63 	int		n = 0;
64 
65 	if (w) {	/* lower bits */
66 		n = ffs(w);
67 	} else {	/* upper bits */
68 		w = (__uint32_t)(v >> 32);
69 		if (w && (n = ffs(w)))
70 		n += 32;
71 	}
72 	return n - 1;
73 }
74 
75 /* Return whether bitmap is empty (1 == empty) */
76 extern int xfs_bitmap_empty(uint *map, uint size);
77 
78 /* Count continuous one bits in map starting with start_bit */
79 extern int xfs_contig_bits(uint *map, uint size, uint start_bit);
80 
81 /* Find next set bit in map */
82 extern int xfs_next_bit(uint *map, uint size, uint start_bit);
83 
84 #endif	/* __XFS_BIT_H__ */
85