kernel26-2.6.12-alx-r9/kernel/kfifo.c

/*
 * A simple kernel FIFO implementation.
 *
 * Copyright (C) 2004 Stelian Pop <stelian@popies.net>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/kfifo.h>

/**
 * kfifo_init - allocates a new FIFO using a preallocated buffer
 * @buffer: the preallocated buffer to be used.
 * @size: the size of the internal buffer, this have to be a power of 2.
 * @gfp_mask: get_free_pages mask, passed to kmalloc()
 * @lock: the lock to be used to protect the fifo buffer
 *
 * Do NOT pass the kfifo to kfifo_free() after use ! Simply free the
 * struct kfifo with kfree().
 */
struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size,
			 unsigned int __nocast gfp_mask, spinlock_t *lock)
{
	struct kfifo *fifo;

	/* size must be a power of 2 */
	BUG_ON(size & (size - 1));

	fifo = kmalloc(sizeof(struct kfifo), gfp_mask);
	if (!fifo)
		return ERR_PTR(-ENOMEM);

	fifo->buffer = buffer;
	fifo->size = size;
	fifo->in = fifo->out = 0;
	fifo->lock = lock;

	return fifo;
}
EXPORT_SYMBOL(kfifo_init);

/**
 * kfifo_alloc - allocates a new FIFO and its internal buffer
 * @size: the size of the internal buffer to be allocated.
 * @gfp_mask: get_free_pages mask, passed to kmalloc()
 * @lock: the lock to be used to protect the fifo buffer
 *
 * The size will be rounded-up to a power of 2.
 */
struct kfifo *kfifo_alloc(unsigned int size, unsigned int __nocast gfp_mask, spinlock_t *lock)
{
	unsigned char *buffer;
	struct kfifo *ret;

	/*
	 * round up to the next power of 2, since our 'let the indices
	 * wrap' tachnique works only in this case.
	 */
	if (size & (size - 1)) {
		BUG_ON(size > 0x80000000);
		size = roundup_pow_of_two(size);
	}

	buffer = kmalloc(size, gfp_mask);
	if (!buffer)
		return ERR_PTR(-ENOMEM);

	ret = kfifo_init(buffer, size, gfp_mask, lock);

	if (IS_ERR(ret))
		kfree(buffer);

	return ret;
}
EXPORT_SYMBOL(kfifo_alloc);

/**
 * kfifo_free - frees the FIFO
 * @fifo: the fifo to be freed.
 */
void kfifo_free(struct kfifo *fifo)
{
	kfree(fifo->buffer);
	kfree(fifo);
}
EXPORT_SYMBOL(kfifo_free);

/**
 * __kfifo_put - puts some data into the FIFO, no locking version
 * @fifo: the fifo to be used.
 * @buffer: the data to be added.
 * @len: the length of the data to be added.
 *
 * This function copies at most 'len' bytes from the 'buffer' into
 * the FIFO depending on the free space, and returns the number of
 * bytes copied.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these functions.
 */
unsigned int __kfifo_put(struct kfifo *fifo,
			 unsigned char *buffer, unsigned int len)
{
	unsigned int l;

	len = min(len, fifo->size - fifo->in + fifo->out);

	/* first put the data starting from fifo->in to buffer end */
	l = min(len, fifo->size - (fifo->in & (fifo->size - 1)));
	memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l);

	/* then put the rest (if any) at the beginning of the buffer */
	memcpy(fifo->buffer, buffer + l, len - l);

	fifo->in += len;

	return len;
}
EXPORT_SYMBOL(__kfifo_put);

/**
 * __kfifo_get - gets some data from the FIFO, no locking version
 * @fifo: the fifo to be used.
 * @buffer: where the data must be copied.
 * @len: the size of the destination buffer.
 *
 * This function copies at most 'len' bytes from the FIFO into the
 * 'buffer' and returns the number of copied bytes.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these functions.
 */
unsigned int __kfifo_get(struct kfifo *fifo,
			 unsigned char *buffer, unsigned int len)
{
	unsigned int l;

	len = min(len, fifo->in - fifo->out);

	/* first get the data from fifo->out until the end of the buffer */
	l = min(len, fifo->size - (fifo->out & (fifo->size - 1)));
	memcpy(buffer, fifo->buffer + (fifo->out & (fifo->size - 1)), l);

	/* then get the rest (if any) from the beginning of the buffer */
	memcpy(buffer + l, fifo->buffer, len - l);

	fifo->out += len;

	return len;
}
EXPORT_SYMBOL(__kfifo_get);
1	niro	628	/*
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
22			#include <linux/kernel.h>
23			#include <linux/module.h>
24			#include <linux/slab.h>
25			#include <linux/err.h>
26			#include <linux/kfifo.h>
27
28			/**
29			* kfifo_init - allocates a new FIFO using a preallocated buffer
30			* @buffer: the preallocated buffer to be used.
31			* @size: the size of the internal buffer, this have to be a power of 2.
32			* @gfp_mask: get_free_pages mask, passed to kmalloc()
33			* @lock: the lock to be used to protect the fifo buffer
34			*
35			* Do NOT pass the kfifo to kfifo_free() after use ! Simply free the
36			* struct kfifo with kfree().
37			*/
38			struct kfifo kfifo_init(unsigned char buffer, unsigned int size,
39			unsigned int __nocast gfp_mask, spinlock_t *lock)
40			{
41			struct kfifo *fifo;
42
43			/* size must be a power of 2 */
44			BUG_ON(size & (size - 1));
45
46			fifo = kmalloc(sizeof(struct kfifo), gfp_mask);
47			if (!fifo)
48			return ERR_PTR(-ENOMEM);
49
50			fifo->buffer = buffer;
51			fifo->size = size;
52			fifo->in = fifo->out = 0;
53			fifo->lock = lock;
54
55			return fifo;
56			}
57			EXPORT_SYMBOL(kfifo_init);
58
59			/**
60			* kfifo_alloc - allocates a new FIFO and its internal buffer
61			* @size: the size of the internal buffer to be allocated.
62			* @gfp_mask: get_free_pages mask, passed to kmalloc()
63			* @lock: the lock to be used to protect the fifo buffer
64			*
65			* The size will be rounded-up to a power of 2.
66			*/
67			struct kfifo kfifo_alloc(unsigned int size, unsigned int __nocast gfp_mask, spinlock_t lock)
68			{
69			unsigned char *buffer;
70			struct kfifo *ret;
71
72			/*
73			* round up to the next power of 2, since our 'let the indices
74			* wrap' tachnique works only in this case.
75			*/
76			if (size & (size - 1)) {
77			BUG_ON(size > 0x80000000);
78			size = roundup_pow_of_two(size);
79			}
80
81			buffer = kmalloc(size, gfp_mask);
82			if (!buffer)
83			return ERR_PTR(-ENOMEM);
84
85			ret = kfifo_init(buffer, size, gfp_mask, lock);
86
87			if (IS_ERR(ret))
88			kfree(buffer);
89
90			return ret;
91			}
92			EXPORT_SYMBOL(kfifo_alloc);
93
94			/**
95			* kfifo_free - frees the FIFO
96			* @fifo: the fifo to be freed.
97			*/
98			void kfifo_free(struct kfifo *fifo)
99			{
100			kfree(fifo->buffer);
101			kfree(fifo);
102			}
103			EXPORT_SYMBOL(kfifo_free);
104
105			/**
106			* __kfifo_put - puts some data into the FIFO, no locking version
107			* @fifo: the fifo to be used.
108			* @buffer: the data to be added.
109			* @len: the length of the data to be added.
110			*
111			* This function copies at most 'len' bytes from the 'buffer' into
112			* the FIFO depending on the free space, and returns the number of
113			* bytes copied.
114			*
115			* Note that with only one concurrent reader and one concurrent
116			* writer, you don't need extra locking to use these functions.
117			*/
118			unsigned int __kfifo_put(struct kfifo *fifo,
119			unsigned char *buffer, unsigned int len)
120			{
121			unsigned int l;
122
123			len = min(len, fifo->size - fifo->in + fifo->out);
124
125			/* first put the data starting from fifo->in to buffer end */
126			l = min(len, fifo->size - (fifo->in & (fifo->size - 1)));
127			memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l);
128
129			/* then put the rest (if any) at the beginning of the buffer */
130			memcpy(fifo->buffer, buffer + l, len - l);
131
132			fifo->in += len;
133
134			return len;
135			}
136			EXPORT_SYMBOL(__kfifo_put);
137
138			/**
139			* __kfifo_get - gets some data from the FIFO, no locking version
140			* @fifo: the fifo to be used.
141			* @buffer: where the data must be copied.
142			* @len: the size of the destination buffer.
143			*
144			* This function copies at most 'len' bytes from the FIFO into the
145			* 'buffer' and returns the number of copied bytes.
146			*
147			* Note that with only one concurrent reader and one concurrent
148			* writer, you don't need extra locking to use these functions.
149			*/
150			unsigned int __kfifo_get(struct kfifo *fifo,
151			unsigned char *buffer, unsigned int len)
152			{
153			unsigned int l;
154
155			len = min(len, fifo->in - fifo->out);
156
157			/* first get the data from fifo->out until the end of the buffer */
158			l = min(len, fifo->size - (fifo->out & (fifo->size - 1)));
159			memcpy(buffer, fifo->buffer + (fifo->out & (fifo->size - 1)), l);
160
161			/* then get the rest (if any) from the beginning of the buffer */
162			memcpy(buffer + l, fifo->buffer, len - l);
163
164			fifo->out += len;
165
166			return len;
167			}
168			EXPORT_SYMBOL(__kfifo_get);