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
  17 along with GNU Zebra; see the file COPYING.  If not, write to the Free
  18 Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, USA.  */
  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__ */