src/queue.h

   1 /* Copyright (c) 2013, Ben Noordhuis <info@bnoordhuis.nl>
   2  *
   3  * Permission to use, copy, modify, and/or distribute this software for any
   4  * purpose with or without fee is hereby granted, provided that the above
   5  * copyright notice and this permission notice appear in all copies.
   6  *
   7  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   8  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   9  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  10  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  11  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  12  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  13  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  14  */
  15
  16 #ifndef SRC_QUEUE_H_
  17 #define SRC_QUEUE_H_
  18
  19 typedef void *QUEUE[2];
  20
  21 /* Private macros. */
  22 #define QUEUE_NEXT(q)       (*(QUEUE **) &((*(q))[0]))
  23 #define QUEUE_PREV(q)       (*(QUEUE **) &((*(q))[1]))
  24 #define QUEUE_PREV_NEXT(q)  (QUEUE_NEXT(QUEUE_PREV(q)))
  25 #define QUEUE_NEXT_PREV(q)  (QUEUE_PREV(QUEUE_NEXT(q)))
  26
  27 /* Public macros. */
  28 #define QUEUE_DATA(ptr, type, field)                                          \
  29   ((type *) ((char *) (ptr) - ((char *) &((type *) 0)->field)))
  30
  31 #define QUEUE_FOREACH(q, h)                                                   \
  32   for ((q) = QUEUE_NEXT(h); (q) != (h); (q) = QUEUE_NEXT(q))
  33
  34 #define QUEUE_EMPTY(q)                                                        \
  35   ((const QUEUE *) (q) == (const QUEUE *) QUEUE_NEXT(q))
  36
  37 #define QUEUE_HEAD(q)                                                         \
  38   (QUEUE_NEXT(q))
  39
  40 #define QUEUE_INIT(q)                                                         \
  41   do {                                                                        \
  42     QUEUE_NEXT(q) = (q);                                                      \
  43     QUEUE_PREV(q) = (q);                                                      \
  44   }                                                                           \
  45   while (0)
  46
  47 #define QUEUE_ADD(h, n)                                                       \
  48   do {                                                                        \
  49     QUEUE_PREV_NEXT(h) = QUEUE_NEXT(n);                                       \
  50     QUEUE_NEXT_PREV(n) = QUEUE_PREV(h);                                       \
  51     QUEUE_PREV(h) = QUEUE_PREV(n);                                            \
  52     QUEUE_PREV_NEXT(h) = (h);                                                 \
  53   }                                                                           \
  54   while (0)
  55
  56 #define QUEUE_SPLIT(h, q, n)                                                  \
  57   do {                                                                        \
  58     QUEUE_PREV(n) = QUEUE_PREV(h);                                            \
  59     QUEUE_PREV_NEXT(n) = (n);                                                 \
  60     QUEUE_NEXT(n) = (q);                                                      \
  61     QUEUE_PREV(h) = QUEUE_PREV(q);                                            \
  62     QUEUE_PREV_NEXT(h) = (h);                                                 \
  63     QUEUE_PREV(q) = (n);                                                      \
  64   }                                                                           \
  65   while (0)
  66
  67 #define QUEUE_INSERT_HEAD(h, q)                                               \
  68   do {                                                                        \
  69     QUEUE_NEXT(q) = QUEUE_NEXT(h);                                            \
  70     QUEUE_PREV(q) = (h);                                                      \
  71     QUEUE_NEXT_PREV(q) = (q);                                                 \
  72     QUEUE_NEXT(h) = (q);                                                      \
  73   }                                                                           \
  74   while (0)
  75
  76 #define QUEUE_INSERT_TAIL(h, q)                                               \
  77   do {                                                                        \
  78     QUEUE_NEXT(q) = (h);                                                      \
  79     QUEUE_PREV(q) = QUEUE_PREV(h);                                            \
  80     QUEUE_PREV_NEXT(q) = (q);                                                 \
  81     QUEUE_PREV(h) = (q);                                                      \
  82   }                                                                           \
  83   while (0)
  84
  85 #define QUEUE_REMOVE(q)                                                       \
  86   do {                                                                        \
  87     QUEUE_PREV_NEXT(q) = QUEUE_NEXT(q);                                       \
  88     QUEUE_NEXT_PREV(q) = QUEUE_PREV(q);                                       \
  89   }                                                                           \
  90   while (0)
  91
  92 #endif  /* SRC_QUEUE_H_ */