/*
* A generic kernel FIFO implementation.
*
* Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
* 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.
*
*/
#ifndef _LINUX_KFIFO_H
#define _LINUX_KFIFO_H
#include <linux/kernel.h>
#include <linux/spinlock.h>
struct kfifo {
unsigned char *buffer; /* the buffer holding the data */
unsigned int size; /* the size of the allocated buffer */
unsigned int in; /* data is added at offset (in % size) */
unsigned int out; /* data is extracted from off. (out % size) */
spinlock_t *lock; /* protects concurrent modifications */
};
extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer,
unsigned int size, spinlock_t *lock);
extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size,
gfp_t gfp_mask, spinlock_t *lock);
extern void kfifo_free(struct kfifo *fifo);
extern unsigned int __kfifo_put(struct kfifo *fifo,
const unsigned char *buffer, unsigned int len);
extern unsigned int __kfifo_get(struct kfifo *fifo,
unsigned char *buffer, unsigned int len);
/**
* __kfifo_reset - removes the entire FIFO contents, no locking version
* @fifo: the fifo to be emptied.
*/
static inline void __kfifo_reset(struct kfifo *fifo)
{
fifo->in = fifo->out = 0;
}
/**
* kfifo_reset - removes the entire FIFO contents
* @fifo: the fifo to be emptied.
*/
static inline void kfifo_reset(struct kfifo *fifo)
{
unsigned long flags;
spin_lock_irqsave(fifo->lock, flags);
__kfifo_reset(fifo);
spin_unlock_irqrestore(fifo->lock, flags);
}
/**
* kfifo_put - puts some data into the FIFO
* @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.
*/
static inline unsigned int kfifo_put(struct kfifo *fifo,
const unsigned char *buffer, unsigned int len)
{
unsigned long flags;
unsigned int ret;
spin_lock_irqsave(fifo->lock, flags);
ret = __kfifo_put(fifo, buffer, len);
spin_unlock_irqrestore(fifo->lock, flags);
return ret;
}
/**
* kfifo_get - gets some data from the FIFO
* @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.
*/
static inline unsigned int kfifo_get(struct kfifo *fifo,
unsigned char *buffer, unsigned int len)
{
unsigned long flags;
unsigned int ret;
spin_lock_irqsave(fifo->lock, flags);
ret = __kfifo_get(fifo, buffer, len);
/*
* optimization: if the FIFO is empty, set the indices to 0
* so we don't wrap the next time
*/
if (fifo->in == fifo->out)
fifo->in = fifo->out = 0;
spin_unlock_irqrestore(fifo->lock, flags);
return ret;
}
/**
* __kfifo_len - returns the number of bytes available in the FIFO, no locking version
* @fifo: the fifo to be used.
*/
static inline unsigned int __kfifo_len(struct kfifo *fifo)
{
return fifo->in - fifo->out;
}
/**
* kfifo_len - returns the number of bytes available in the FIFO
* @fifo: the fifo to be used.
*/
static inline unsigned int kfifo_len(struct kfifo *fifo)
{
unsigned long flags;
unsigned int ret;
spin_lock_irqsave(fifo->lock, flags);
ret = __kfifo_len(fifo);
spin_unlock_irqrestore(fifo->lock, flags);
return ret;
}
#endif
