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
|
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include "bge_impl.h"
/*
* Atomically decrement a counter, but only if it will remain
* strictly positive (greater than zero) afterwards. We return
* the decremented value if so, otherwise zero (in which case
* the counter is unchanged).
*
* This is used for keeping track of available resources such
* as transmit ring slots ...
*/
uint64_t
bge_atomic_reserve(uint64_t *count_p, uint64_t n)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *count_p;
newval = oldval - n;
if (oldval <= n)
return (0); /* no resources left */
} while (atomic_cas_64(count_p, oldval, newval) != oldval);
return (newval);
}
/*
* Atomically increment a counter
*/
void
bge_atomic_renounce(uint64_t *count_p, uint64_t n)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *count_p;
newval = oldval + n;
} while (atomic_cas_64(count_p, oldval, newval) != oldval);
}
/*
* Atomically claim a slot in a descriptor ring
*/
uint64_t
bge_atomic_claim(uint64_t *count_p, uint64_t limit)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *count_p;
newval = NEXT(oldval, limit);
} while (atomic_cas_64(count_p, oldval, newval) != oldval);
return (oldval);
}
/*
* Atomically NEXT a 64-bit integer, returning the
* value it had *before* the NEXT was applied
*/
uint64_t
bge_atomic_next(uint64_t *sp, uint64_t limit)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *sp;
newval = NEXT(oldval, limit);
} while (atomic_cas_64(sp, oldval, newval) != oldval);
return (oldval);
}
/*
* Atomically decrement a counter
*/
void
bge_atomic_sub64(uint64_t *count_p, uint64_t n)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *count_p;
newval = oldval - n;
} while (atomic_cas_64(count_p, oldval, newval) != oldval);
}
/*
* Atomically clear bits in a 64-bit word, returning
* the value it had *before* the bits were cleared.
*/
uint64_t
bge_atomic_clr64(uint64_t *sp, uint64_t bits)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *sp;
newval = oldval & ~bits;
} while (atomic_cas_64(sp, oldval, newval) != oldval);
return (oldval);
}
/*
* Atomically shift a 32-bit word left, returning
* the value it had *before* the shift was applied
*/
uint32_t
bge_atomic_shl32(uint32_t *sp, uint_t count)
{
uint32_t oldval;
uint32_t newval;
/* ATOMICALLY */
do {
oldval = *sp;
newval = oldval << count;
} while (atomic_cas_32(sp, oldval, newval) != oldval);
return (oldval);
}
|
