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 {
  26   struct fifo *next;
  27   struct fifo *prev;
  28 };
  29
  30 #define FIFO_INIT(F)                                  \
  31   do {                                                \
  32     struct fifo *Xfifo = (struct fifo *)(F);          \
  33     Xfifo->next = Xfifo->prev = Xfifo;                \
  34   } while (0)
  35
  36 #define FIFO_ADD(F,N)                                 \
  37   do {                                                \
  38     struct fifo *Xfifo = (struct fifo *)(F);          \
  39     struct fifo *Xnode = (struct fifo *)(N);          \
  40     Xnode->next = Xfifo;                              \
  41     Xnode->prev = Xfifo->prev;                        \
  42     Xfifo->prev = Xfifo->prev->next = Xnode;          \
  43   } while (0)
  44
  45 #define FIFO_DEL(N)                                   \
  46   do {                                                \
  47     struct fifo *Xnode = (struct fifo *)(N);          \
  48     Xnode->prev->next = Xnode->next;                  \
  49     Xnode->next->prev = Xnode->prev;                  \
  50   } while (0)
  51
  52 #define FIFO_HEAD(F)                                  \
  53   ((((struct fifo *)(F))->next == (struct fifo *)(F)) \
  54   ? NULL : (F)->next)
  55
  56 #define FIFO_EMPTY(F)                                 \
  57   (((struct fifo *)(F))->next == (struct fifo *)(F))
  58
  59 #define FIFO_TOP(F)                                   \
  60   (FIFO_EMPTY(F) ? NULL : ((struct fifo *)(F))->next)
  61
  62 #endif /* __LIB_FIFO_H__ */