blob: 4c3a836a014a615a516253c4bbfde5bed51758f7 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
/*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* Copyright (C) 2008 IBM Corporation
* Written by Rusty Russell <rusty@rustcorp.com.au>
* (Inspired by David Howell's find_next_bit implementation)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include "qemu/bitops.h"
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
/*
* Find the next set bit in a memory region.
*/
unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
unsigned long offset)
{
const unsigned long *p = addr + BITOP_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG-1);
unsigned long tmp;
if (offset >= size) {
return size;
}
size -= result;
offset %= BITS_PER_LONG;
if (offset) {
tmp = *(p++);
tmp &= (~0UL << offset);
if (size < BITS_PER_LONG) {
goto found_first;
}
if (tmp) {
goto found_middle;
}
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
while (size & ~(BITS_PER_LONG-1)) {
if ((tmp = *(p++))) {
goto found_middle;
}
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size) {
return result;
}
tmp = *p;
found_first:
tmp &= (~0UL >> (BITS_PER_LONG - size));
if (tmp == 0UL) { /* Are any bits set? */
return result + size; /* Nope. */
}
found_middle:
return result + bitops_ffsl(tmp);
}
/*
* This implementation of find_{first,next}_zero_bit was stolen from
* Linus' asm-alpha/bitops.h.
*/
unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
unsigned long offset)
{
const unsigned long *p = addr + BITOP_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG-1);
unsigned long tmp;
if (offset >= size) {
return size;
}
size -= result;
offset %= BITS_PER_LONG;
if (offset) {
tmp = *(p++);
tmp |= ~0UL >> (BITS_PER_LONG - offset);
if (size < BITS_PER_LONG) {
goto found_first;
}
if (~tmp) {
goto found_middle;
}
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
while (size & ~(BITS_PER_LONG-1)) {
if (~(tmp = *(p++))) {
goto found_middle;
}
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size) {
return result;
}
tmp = *p;
found_first:
tmp |= ~0UL << size;
if (tmp == ~0UL) { /* Are any bits zero? */
return result + size; /* Nope. */
}
found_middle:
return result + ffz(tmp);
}
unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
{
unsigned long words;
unsigned long tmp;
/* Start at final word. */
words = size / BITS_PER_LONG;
/* Partial final word? */
if (size & (BITS_PER_LONG-1)) {
tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
- (size & (BITS_PER_LONG-1)))));
if (tmp) {
goto found;
}
}
while (words) {
tmp = addr[--words];
if (tmp) {
found:
return words * BITS_PER_LONG + bitops_flsl(tmp);
}
}
/* Not found */
return size;
}
|
