lib/fifo.h

   1 /* FIFO common header.
   2  * Copyright (C) 2015 Kunihiro Ishiguro
   3  *
   4  * This file is part of Quagga.
   5  *
   6  * Quagga is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * Quagga is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20 #ifndef __LIB_FIFO_H__
  21 #define __LIB_FIFO_H__
  22
  23 /* FIFO -- first in first out structure and macros.  */
  24 struct fifo {
  25         struct fifo *next;
  26         struct fifo *prev;
  27 };
  28
  29 #define FIFO_INIT(F)                                                           \
  30         do {                                                                   \
  31                 struct fifo *Xfifo = (struct fifo *)(F);                       \
  32                 Xfifo->next = Xfifo->prev = Xfifo;                             \
  33         } while (0)
  34
  35 #define FIFO_ADD(F, N)                                                         \
  36         do {                                                                   \
  37                 struct fifo *Xfifo = (struct fifo *)(F);                       \
  38                 struct fifo *Xnode = (struct fifo *)(N);                       \
  39                 Xnode->next = Xfifo;                                           \
  40                 Xnode->prev = Xfifo->prev;                                     \
  41                 Xfifo->prev = Xfifo->prev->next = Xnode;                       \
  42         } while (0)
  43
  44 #define FIFO_DEL(N)                                                            \
  45         do {                                                                   \
  46                 struct fifo *Xnode = (struct fifo *)(N);                       \
  47                 Xnode->prev->next = Xnode->next;                               \
  48                 Xnode->next->prev = Xnode->prev;                               \
  49         } while (0)
  50
  51 #define FIFO_HEAD(F)                                                           \
  52         ((((struct fifo *)(F))->next == (struct fifo *)(F)) ? NULL : (F)->next)
  53
  54 #define FIFO_EMPTY(F) (((struct fifo *)(F))->next == (struct fifo *)(F))
  55
  56 #define FIFO_TOP(F) (FIFO_EMPTY(F) ? NULL : ((struct fifo *)(F))->next)
  57
  58 #endif /* __LIB_FIFO_H__ */