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quagga 1.0.20160315

/* FIFO common header.
   Copyright (C) 2015 Kunihiro Ishiguro

This file is part of Quagga.

Quagga 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, or (at your option) any
later version.

Quagga 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 GNU Zebra; see the file COPYING.  If not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */
#ifndef __LIB_FIFO_H__
#define __LIB_FIFO_H__

/* FIFO -- first in first out structure and macros.  */
struct fifo
{
  struct fifo *next;
  struct fifo *prev;
};

#define FIFO_INIT(F)                                  \
  do {                                                \
    struct fifo *Xfifo = (struct fifo *)(F);          \
    Xfifo->next = Xfifo->prev = Xfifo;                \
  } while (0)

#define FIFO_ADD(F,N)                                 \
  do {                                                \
    struct fifo *Xfifo = (struct fifo *)(F);          \
    struct fifo *Xnode = (struct fifo *)(N);          \
    Xnode->next = Xfifo;                              \
    Xnode->prev = Xfifo->prev;                        \
    Xfifo->prev = Xfifo->prev->next = Xnode;          \
  } while (0)

#define FIFO_DEL(N)                                   \
  do {                                                \
    struct fifo *Xnode = (struct fifo *)(N);          \
    Xnode->prev->next = Xnode->next;                  \
    Xnode->next->prev = Xnode->prev;                  \
  } while (0)

#define FIFO_HEAD(F)                                  \
  ((((struct fifo *)(F))->next == (struct fifo *)(F)) \
  ? NULL : (F)->next)

#define FIFO_EMPTY(F)                                 \
  (((struct fifo *)(F))->next == (struct fifo *)(F))

#define FIFO_TOP(F)                                   \
  (FIFO_EMPTY(F) ? NULL : ((struct fifo *)(F))->next)

#endif /* __LIB_FIFO_H__ */