/***
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*
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* include/rtskb_fifo.h
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*
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* RTnet - real-time networking subsystem
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* Copyright (C) 2006 Jan Kiszka <jan.kiszka@web.de>
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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 __RTSKB_FIFO_H_
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#define __RTSKB_FIFO_H_
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#include <rtskb.h>
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struct rtskb_fifo {
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unsigned long read_pos ____cacheline_aligned_in_smp;
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rtdm_lock_t read_lock;
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unsigned long size_mask;
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unsigned long write_pos ____cacheline_aligned_in_smp;
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rtdm_lock_t write_lock;
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struct rtskb *buffer[0];
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};
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#define DECLARE_RTSKB_FIFO(name_prefix, size) \
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struct { \
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struct rtskb_fifo fifo; \
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struct rtskb *__buffer[(size)]; \
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} name_prefix
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static inline int __rtskb_fifo_insert(struct rtskb_fifo *fifo,
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struct rtskb *rtskb)
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{
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unsigned long pos = fifo->write_pos;
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unsigned long new_pos = (pos + 1) & fifo->size_mask;
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if (unlikely(new_pos == fifo->read_pos))
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return -EAGAIN;
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fifo->buffer[pos] = rtskb;
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/* rtskb must have been written before write_pos update */
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smp_wmb();
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fifo->write_pos = new_pos;
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return 0;
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}
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static inline int rtskb_fifo_insert(struct rtskb_fifo *fifo,
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struct rtskb *rtskb)
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{
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rtdm_lockctx_t context;
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int result;
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rtdm_lock_get_irqsave(&fifo->write_lock, context);
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result = __rtskb_fifo_insert(fifo, rtskb);
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rtdm_lock_put_irqrestore(&fifo->write_lock, context);
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return result;
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}
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static inline int rtskb_fifo_insert_inirq(struct rtskb_fifo *fifo,
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struct rtskb *rtskb)
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{
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int result;
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rtdm_lock_get(&fifo->write_lock);
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result = __rtskb_fifo_insert(fifo, rtskb);
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rtdm_lock_put(&fifo->write_lock);
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return result;
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}
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static inline struct rtskb *__rtskb_fifo_remove(struct rtskb_fifo *fifo)
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{
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unsigned long pos = fifo->read_pos;
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struct rtskb *result;
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/* check FIFO status first */
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if (unlikely(pos == fifo->write_pos))
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return NULL;
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/* at least one rtskb is enqueued, so get the next one */
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result = fifo->buffer[pos];
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/* result must have been read before read_pos update */
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smp_rmb();
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fifo->read_pos = (pos + 1) & fifo->size_mask;
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/* read_pos must have been written for a consitent fifo state on exit */
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smp_wmb();
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return result;
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}
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static inline struct rtskb *rtskb_fifo_remove(struct rtskb_fifo *fifo)
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{
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rtdm_lockctx_t context;
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struct rtskb *result;
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rtdm_lock_get_irqsave(&fifo->read_lock, context);
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result = __rtskb_fifo_remove(fifo);
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rtdm_lock_put_irqrestore(&fifo->read_lock, context);
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return result;
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}
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static inline struct rtskb *rtskb_fifo_remove_inirq(struct rtskb_fifo *fifo)
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{
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struct rtskb *result;
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rtdm_lock_get(&fifo->read_lock);
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result = __rtskb_fifo_remove(fifo);
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rtdm_lock_put(&fifo->read_lock);
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return result;
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}
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/* for now inlined... */
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static inline void rtskb_fifo_init(struct rtskb_fifo *fifo, unsigned long size)
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{
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fifo->read_pos = 0;
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fifo->write_pos = 0;
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fifo->size_mask = size - 1;
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rtdm_lock_init(&fifo->read_lock);
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rtdm_lock_init(&fifo->write_lock);
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}
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#endif /* __RTSKB_FIFO_H_ */
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