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
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
/* $FreeBSD$ */
/*
* this is mixture of i386/bitops.h and asm/string.h
* taken from the Linux source tree
*
* XXX replace with Mach routines or reprogram in C
*/
#ifndef _SYS_GNU_EXT2FS_I386_BITOPS_H_
#define _SYS_GNU_EXT2FS_I386_BITOPS_H_
/*
* Copyright 1992, Linus Torvalds.
*/
/*
* These have to be done with inline assembly: that way the bit-setting
* is guaranteed to be atomic. All bit operations return 0 if the bit
* was cleared before the operation and != 0 if it was not.
*
* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
*/
/*
* Some hacks to defeat gcc over-optimizations..
*/
struct __dummy { unsigned long a[100]; };
#define ADDR (*(struct __dummy *) addr)
static __inline__ int set_bit(int nr, void * addr)
{
int oldbit;
__asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"ir" (nr));
return oldbit;
}
static __inline__ int clear_bit(int nr, void * addr)
{
int oldbit;
__asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"ir" (nr));
return oldbit;
}
static __inline__ int change_bit(int nr, void * addr)
{
int oldbit;
__asm__ __volatile__("btcl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"ir" (nr));
return oldbit;
}
/*
* This routine doesn't need to be atomic, but it's faster to code it
* this way.
*/
static __inline__ int test_bit(int nr, void * addr)
{
int oldbit;
__asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit)
:"m" (ADDR),"ir" (nr));
return oldbit;
}
/*
* Find-bit routines..
*/
static __inline__ int find_first_zero_bit(void * addr, unsigned size)
{
int res;
int _count = (size + 31) >> 5;
if (!size)
return 0;
__asm__(" \n\
cld \n\
movl $-1,%%eax \n\
xorl %%edx,%%edx \n\
repe; scasl \n\
je 1f \n\
xorl -4(%%edi),%%eax \n\
subl $4,%%edi \n\
bsfl %%eax,%%edx \n\
1: subl %%ebx,%%edi \n\
shll $3,%%edi \n\
addl %%edi,%%edx"
: "=c" (_count), "=D" (addr), "=d" (res)
: "0" (_count), "1" (addr), "b" (addr)
: "ax");
return res;
}
static __inline__ int find_next_zero_bit (void * addr, int size, int offset)
{
unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
int set = 0, bit = offset & 31, res;
if (bit) {
/*
* Look for zero in first byte
*/
__asm__(" \n\
bsfl %1,%0 \n\
jne 1f \n\
movl $32, %0 \n\
1: "
: "=r" (set)
: "r" (~(*p >> bit)));
if (set < (32 - bit))
return set + offset;
set = 32 - bit;
p++;
}
/*
* No zero yet, search remaining full bytes for a zero
*/
res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
return (offset + set + res);
}
/*
* ffz = Find First Zero in word. Undefined if no zero exists,
* so code should check against ~0UL first..
*/
static __inline__ unsigned long ffz(unsigned long word)
{
__asm__("bsfl %1,%0"
:"=r" (word)
:"r" (~word));
return word;
}
/*
* memscan() taken from linux asm/string.h
*/
/*
* find the first occurrence of byte 'c', or 1 past the area if none
*/
static __inline__ char * memscan(void * addr, unsigned char c, int size)
{
if (!size)
return addr;
__asm__(" \n\
cld \n\
repnz; scasb \n\
jnz 1f \n\
dec %%edi \n\
1: "
: "=D" (addr), "=c" (size)
: "0" (addr), "1" (size), "a" (c));
return addr;
}
#endif /* !_SYS_GNU_EXT2FS_I386_BITOPS_H_ */
|
