2 * A simple kernel FIFO implementation.
4 * Copyright (C) 2004 Stelian Pop <stelian@popies.net>
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.
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.
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.
21 #ifndef _LINUX_KFIFO_H
22 #define _LINUX_KFIFO_H
26 #include <linux/kernel.h>
27 #include <linux/spinlock.h>
30 unsigned char *buffer; /* the buffer holding the data */
31 unsigned int size; /* the size of the allocated buffer */
32 unsigned int in; /* data is added at offset (in % size) */
33 unsigned int out; /* data is extracted from off. (out % size) */
34 spinlock_t *lock; /* protects concurrent modifications */
37 extern struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size,
38 gfp_t gfp_mask, spinlock_t *lock);
39 extern struct kfifo *kfifo_alloc(unsigned int size, gfp_t gfp_mask,
41 extern void kfifo_free(struct kfifo *fifo);
42 extern unsigned int __kfifo_put(struct kfifo *fifo,
43 unsigned char *buffer, unsigned int len);
44 extern unsigned int __kfifo_get(struct kfifo *fifo,
45 unsigned char *buffer, unsigned int len);
46 extern unsigned int __kfifo_get_to_user(struct kfifo *fifo,
47 unsigned char __user *buffer,
51 * __kfifo_reset - removes the entire FIFO contents, no locking version
52 * @fifo: the fifo to be emptied.
54 static inline void __kfifo_reset(struct kfifo *fifo)
56 fifo->in = fifo->out = 0;
60 * kfifo_reset - removes the entire FIFO contents
61 * @fifo: the fifo to be emptied.
63 static inline void kfifo_reset(struct kfifo *fifo)
67 spin_lock_irqsave(fifo->lock, flags);
71 spin_unlock_irqrestore(fifo->lock, flags);
75 * kfifo_put - puts some data into the FIFO
76 * @fifo: the fifo to be used.
77 * @buffer: the data to be added.
78 * @len: the length of the data to be added.
80 * This function copies at most @len bytes from the @buffer into
81 * the FIFO depending on the free space, and returns the number of
84 static inline unsigned int kfifo_put(struct kfifo *fifo,
85 unsigned char *buffer, unsigned int len)
90 spin_lock_irqsave(fifo->lock, flags);
92 ret = __kfifo_put(fifo, buffer, len);
94 spin_unlock_irqrestore(fifo->lock, flags);
100 * kfifo_get - gets some data from the FIFO
101 * @fifo: the fifo to be used.
102 * @buffer: where the data must be copied.
103 * @len: the size of the destination buffer.
105 * This function copies at most @len bytes from the FIFO into the
106 * @buffer and returns the number of copied bytes.
108 static inline unsigned int kfifo_get(struct kfifo *fifo,
109 unsigned char *buffer, unsigned int len)
114 spin_lock_irqsave(fifo->lock, flags);
116 ret = __kfifo_get(fifo, buffer, len);
119 * optimization: if the FIFO is empty, set the indices to 0
120 * so we don't wrap the next time
122 if (fifo->in == fifo->out)
123 fifo->in = fifo->out = 0;
125 spin_unlock_irqrestore(fifo->lock, flags);
131 * __kfifo_len - returns the number of bytes available in the FIFO, no locking version
132 * @fifo: the fifo to be used.
134 static inline unsigned int __kfifo_len(struct kfifo *fifo)
136 return fifo->in - fifo->out;
140 * kfifo_len - returns the number of bytes available in the FIFO
141 * @fifo: the fifo to be used.
143 static inline unsigned int kfifo_len(struct kfifo *fifo)
148 spin_lock_irqsave(fifo->lock, flags);
150 ret = __kfifo_len(fifo);
152 spin_unlock_irqrestore(fifo->lock, flags);
158 * kfifo_get_to_user - gets some data from the FIFO
159 * @fifo: the fifo to be used.
160 * @buffer: where the data must be copied. user buffer
161 * @len: the size of the destination buffer.
163 * This function copies at most @len bytes from the FIFO into the
164 * user @buffer and returns the number of copied bytes.
166 static inline unsigned int kfifo_get_to_user(struct kfifo *fifo,
167 unsigned char __user *buffer,
173 spin_lock_irqsave(fifo->lock, flags);
175 ret = __kfifo_get_to_user(fifo, buffer, len);
178 * optimization: if the FIFO is empty, set the indices to 0
179 * so we don't wrap the next time
181 if (fifo->in == fifo->out)
182 fifo->in = fifo->out = 0;
184 spin_unlock_irqrestore(fifo->lock, flags);
190 #warning "don't include kernel headers in userspace"
191 #endif /* __KERNEL__ */