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1da177e4 LT |
1 | /* |
2 | * A simple kernel FIFO implementation. | |
3 | * | |
4 | * Copyright (C) 2004 Stelian Pop <stelian@popies.net> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | * | |
20 | */ | |
21 | #ifndef _LINUX_KFIFO_H | |
22 | #define _LINUX_KFIFO_H | |
23 | ||
1da177e4 LT |
24 | #include <linux/kernel.h> |
25 | #include <linux/spinlock.h> | |
26 | ||
27 | struct kfifo { | |
28 | unsigned char *buffer; /* the buffer holding the data */ | |
29 | unsigned int size; /* the size of the allocated buffer */ | |
30 | unsigned int in; /* data is added at offset (in % size) */ | |
31 | unsigned int out; /* data is extracted from off. (out % size) */ | |
32 | spinlock_t *lock; /* protects concurrent modifications */ | |
33 | }; | |
34 | ||
35 | extern struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size, | |
dd0fc66f AV |
36 | gfp_t gfp_mask, spinlock_t *lock); |
37 | extern struct kfifo *kfifo_alloc(unsigned int size, gfp_t gfp_mask, | |
1da177e4 LT |
38 | spinlock_t *lock); |
39 | extern void kfifo_free(struct kfifo *fifo); | |
40 | extern unsigned int __kfifo_put(struct kfifo *fifo, | |
f8a7c1a9 | 41 | const unsigned char *buffer, unsigned int len); |
1da177e4 LT |
42 | extern unsigned int __kfifo_get(struct kfifo *fifo, |
43 | unsigned char *buffer, unsigned int len); | |
44 | ||
45 | /** | |
46 | * __kfifo_reset - removes the entire FIFO contents, no locking version | |
47 | * @fifo: the fifo to be emptied. | |
48 | */ | |
49 | static inline void __kfifo_reset(struct kfifo *fifo) | |
50 | { | |
51 | fifo->in = fifo->out = 0; | |
52 | } | |
53 | ||
54 | /** | |
55 | * kfifo_reset - removes the entire FIFO contents | |
56 | * @fifo: the fifo to be emptied. | |
57 | */ | |
58 | static inline void kfifo_reset(struct kfifo *fifo) | |
59 | { | |
60 | unsigned long flags; | |
61 | ||
62 | spin_lock_irqsave(fifo->lock, flags); | |
63 | ||
64 | __kfifo_reset(fifo); | |
65 | ||
66 | spin_unlock_irqrestore(fifo->lock, flags); | |
67 | } | |
68 | ||
69 | /** | |
70 | * kfifo_put - puts some data into the FIFO | |
71 | * @fifo: the fifo to be used. | |
72 | * @buffer: the data to be added. | |
73 | * @len: the length of the data to be added. | |
74 | * | |
72fd4a35 | 75 | * This function copies at most @len bytes from the @buffer into |
1da177e4 LT |
76 | * the FIFO depending on the free space, and returns the number of |
77 | * bytes copied. | |
78 | */ | |
79 | static inline unsigned int kfifo_put(struct kfifo *fifo, | |
f8a7c1a9 | 80 | const unsigned char *buffer, unsigned int len) |
1da177e4 LT |
81 | { |
82 | unsigned long flags; | |
83 | unsigned int ret; | |
84 | ||
85 | spin_lock_irqsave(fifo->lock, flags); | |
86 | ||
87 | ret = __kfifo_put(fifo, buffer, len); | |
88 | ||
89 | spin_unlock_irqrestore(fifo->lock, flags); | |
90 | ||
91 | return ret; | |
92 | } | |
93 | ||
94 | /** | |
95 | * kfifo_get - gets some data from the FIFO | |
96 | * @fifo: the fifo to be used. | |
97 | * @buffer: where the data must be copied. | |
98 | * @len: the size of the destination buffer. | |
99 | * | |
72fd4a35 RD |
100 | * This function copies at most @len bytes from the FIFO into the |
101 | * @buffer and returns the number of copied bytes. | |
1da177e4 LT |
102 | */ |
103 | static inline unsigned int kfifo_get(struct kfifo *fifo, | |
104 | unsigned char *buffer, unsigned int len) | |
105 | { | |
106 | unsigned long flags; | |
107 | unsigned int ret; | |
108 | ||
109 | spin_lock_irqsave(fifo->lock, flags); | |
110 | ||
111 | ret = __kfifo_get(fifo, buffer, len); | |
112 | ||
113 | /* | |
114 | * optimization: if the FIFO is empty, set the indices to 0 | |
115 | * so we don't wrap the next time | |
116 | */ | |
117 | if (fifo->in == fifo->out) | |
118 | fifo->in = fifo->out = 0; | |
119 | ||
120 | spin_unlock_irqrestore(fifo->lock, flags); | |
121 | ||
122 | return ret; | |
123 | } | |
124 | ||
125 | /** | |
126 | * __kfifo_len - returns the number of bytes available in the FIFO, no locking version | |
127 | * @fifo: the fifo to be used. | |
128 | */ | |
129 | static inline unsigned int __kfifo_len(struct kfifo *fifo) | |
130 | { | |
131 | return fifo->in - fifo->out; | |
132 | } | |
133 | ||
134 | /** | |
135 | * kfifo_len - returns the number of bytes available in the FIFO | |
136 | * @fifo: the fifo to be used. | |
137 | */ | |
138 | static inline unsigned int kfifo_len(struct kfifo *fifo) | |
139 | { | |
140 | unsigned long flags; | |
141 | unsigned int ret; | |
142 | ||
143 | spin_lock_irqsave(fifo->lock, flags); | |
144 | ||
145 | ret = __kfifo_len(fifo); | |
146 | ||
147 | spin_unlock_irqrestore(fifo->lock, flags); | |
148 | ||
149 | return ret; | |
150 | } | |
151 | ||
1da177e4 | 152 | #endif |