158 lines
4.1 KiB
C
158 lines
4.1 KiB
C
/*
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* A simple kernel FIFO implementation.
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*
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* Copyright (C) 2004 Stelian Pop <stelian@popies.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#ifndef _LINUX_KFIFO_H
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#define _LINUX_KFIFO_H
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#ifdef __KERNEL__
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#include <linux/kernel.h>
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#include <linux/spinlock.h>
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struct kfifo {
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unsigned char *buffer; /* the buffer holding the data */
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unsigned int size; /* the size of the allocated buffer */
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unsigned int in; /* data is added at offset (in % size) */
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unsigned int out; /* data is extracted from off. (out % size) */
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spinlock_t *lock; /* protects concurrent modifications */
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};
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extern struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size,
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gfp_t gfp_mask, spinlock_t *lock);
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extern struct kfifo *kfifo_alloc(unsigned int size, gfp_t gfp_mask,
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spinlock_t *lock);
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extern void kfifo_free(struct kfifo *fifo);
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extern unsigned int __kfifo_put(struct kfifo *fifo,
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unsigned char *buffer, unsigned int len);
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extern unsigned int __kfifo_get(struct kfifo *fifo,
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unsigned char *buffer, unsigned int len);
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/**
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* __kfifo_reset - removes the entire FIFO contents, no locking version
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* @fifo: the fifo to be emptied.
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*/
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static inline void __kfifo_reset(struct kfifo *fifo)
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{
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fifo->in = fifo->out = 0;
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}
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/**
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* kfifo_reset - removes the entire FIFO contents
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* @fifo: the fifo to be emptied.
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*/
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static inline void kfifo_reset(struct kfifo *fifo)
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{
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unsigned long flags;
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spin_lock_irqsave(fifo->lock, flags);
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__kfifo_reset(fifo);
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spin_unlock_irqrestore(fifo->lock, flags);
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}
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/**
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* kfifo_put - puts some data into the FIFO
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* @fifo: the fifo to be used.
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* @buffer: the data to be added.
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* @len: the length of the data to be added.
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*
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* This function copies at most 'len' bytes from the 'buffer' into
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* the FIFO depending on the free space, and returns the number of
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* bytes copied.
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*/
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static inline unsigned int kfifo_put(struct kfifo *fifo,
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unsigned char *buffer, unsigned int len)
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{
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unsigned long flags;
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unsigned int ret;
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spin_lock_irqsave(fifo->lock, flags);
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ret = __kfifo_put(fifo, buffer, len);
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spin_unlock_irqrestore(fifo->lock, flags);
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return ret;
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}
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/**
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* kfifo_get - gets some data from the FIFO
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* @fifo: the fifo to be used.
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* @buffer: where the data must be copied.
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* @len: the size of the destination buffer.
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*
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* This function copies at most 'len' bytes from the FIFO into the
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* 'buffer' and returns the number of copied bytes.
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*/
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static inline unsigned int kfifo_get(struct kfifo *fifo,
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unsigned char *buffer, unsigned int len)
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{
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unsigned long flags;
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unsigned int ret;
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spin_lock_irqsave(fifo->lock, flags);
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ret = __kfifo_get(fifo, buffer, len);
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/*
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* optimization: if the FIFO is empty, set the indices to 0
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* so we don't wrap the next time
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*/
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if (fifo->in == fifo->out)
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fifo->in = fifo->out = 0;
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spin_unlock_irqrestore(fifo->lock, flags);
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return ret;
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}
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/**
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* __kfifo_len - returns the number of bytes available in the FIFO, no locking version
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* @fifo: the fifo to be used.
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*/
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static inline unsigned int __kfifo_len(struct kfifo *fifo)
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{
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return fifo->in - fifo->out;
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}
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/**
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* kfifo_len - returns the number of bytes available in the FIFO
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* @fifo: the fifo to be used.
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*/
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static inline unsigned int kfifo_len(struct kfifo *fifo)
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{
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unsigned long flags;
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unsigned int ret;
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spin_lock_irqsave(fifo->lock, flags);
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ret = __kfifo_len(fifo);
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spin_unlock_irqrestore(fifo->lock, flags);
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return ret;
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}
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#else
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#warning "don't include kernel headers in userspace"
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#endif /* __KERNEL__ */
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#endif
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