lib/libc/stdlib/qr.h

   1 /******************************************************************************
   2  *
   3  * Copyright (C) 2002 Jason Evans <jasone@FreeBSD.org>.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice(s), this list of conditions and the following disclaimer
  11  *    unmodified other than the allowable addition of one or more
  12  *    copyright notices.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice(s), this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
  19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  21  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
  22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  25  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  26  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  27  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  28  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  ******************************************************************************/
  31
  32 #ifndef QR_H_
  33 #define QR_H_
  34
  35 #include <sys/cdefs.h>
  36 __FBSDID("$FreeBSD$");
  37
  38 /* Ring definitions. */
  39 #define qr(a_type)                                                      \
  40 struct {                                                                \
  41         a_type  *qre_next;                                              \
  42         a_type  *qre_prev;                                              \
  43 }
  44
  45 /* Ring functions. */
  46 #define qr_new(a_qr, a_field) do {                                      \
  47         (a_qr)->a_field.qre_next = (a_qr);                              \
  48         (a_qr)->a_field.qre_prev = (a_qr);                              \
  49 } while (0)
  50
  51 #define qr_next(a_qr, a_field) ((a_qr)->a_field.qre_next)
  52
  53 #define qr_prev(a_qr, a_field) ((a_qr)->a_field.qre_prev)
  54
  55 #define qr_before_insert(a_qrelm, a_qr, a_field) do {                   \
  56         (a_qr)->a_field.qre_prev = (a_qrelm)->a_field.qre_prev;         \
  57         (a_qr)->a_field.qre_next = (a_qrelm);                           \
  58         (a_qr)->a_field.qre_prev->a_field.qre_next = (a_qr);            \
  59         (a_qrelm)->a_field.qre_prev = (a_qr);                           \
  60 } while (0)
  61
  62 #define qr_after_insert(a_qrelm, a_qr, a_field)                         \
  63     do                                                                  \
  64     {                                                                   \
  65         (a_qr)->a_field.qre_next = (a_qrelm)->a_field.qre_next;         \
  66         (a_qr)->a_field.qre_prev = (a_qrelm);                           \
  67         (a_qr)->a_field.qre_next->a_field.qre_prev = (a_qr);            \
  68         (a_qrelm)->a_field.qre_next = (a_qr);                           \
  69     } while (0)
  70
  71 #define qr_meld(a_qr_a, a_qr_b, a_field) do {                           \
  72         void *t;                                                        \
  73         (a_qr_a)->a_field.qre_prev->a_field.qre_next = (a_qr_b);        \
  74         (a_qr_b)->a_field.qre_prev->a_field.qre_next = (a_qr_a);        \
  75         t = (a_qr_a)->a_field.qre_prev;                                 \
  76         (a_qr_a)->a_field.qre_prev = (a_qr_b)->a_field.qre_prev;        \
  77         (a_qr_b)->a_field.qre_prev = t;                                 \
  78 } while (0)
  79
  80 /* qr_meld() and qr_split() are functionally equivalent, so there's no need to
  81  * have two copies of the code. */
  82 #define qr_split(a_qr_a, a_qr_b, a_field)                               \
  83         qr_meld((a_qr_a), (a_qr_b), a_field)
  84
  85 #define qr_remove(a_qr, a_field) do {                                   \
  86         (a_qr)->a_field.qre_prev->a_field.qre_next                      \
  87             = (a_qr)->a_field.qre_next;                                 \
  88         (a_qr)->a_field.qre_next->a_field.qre_prev                      \
  89             = (a_qr)->a_field.qre_prev;                                 \
  90         (a_qr)->a_field.qre_next = (a_qr);                              \
  91         (a_qr)->a_field.qre_prev = (a_qr);                              \
  92 } while (0)
  93
  94 #define qr_foreach(var, a_qr, a_field)                                  \
  95         for ((var) = (a_qr);                                            \
  96             (var) != NULL;                                              \
  97             (var) = (((var)->a_field.qre_next != (a_qr))                \
  98             ? (var)->a_field.qre_next : NULL))
  99
 100 #define qr_reverse_foreach(var, a_qr, a_field)                          \
 101         for ((var) = ((a_qr) != NULL) ? qr_prev(a_qr, a_field) : NULL;  \
 102             (var) != NULL;                                              \
 103             (var) = (((var) != (a_qr))                                  \
 104             ? (var)->a_field.qre_prev : NULL))
 105
 106 #endif /* QR_H_ */