util/range.c

   1 /*
   2  * QEMU 64-bit address ranges
   3  *
   4  * Copyright (c) 2015-2016 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "qemu/range.h"
  23
  24 /*
  25  * Operations on 64 bit address ranges.
  26  * Notes:
  27  *   - ranges must not wrap around 0, but can include the last byte ~0x0LL.
  28  *   - this can not represent a full 0 to ~0x0LL range.
  29  */
  30
  31 /* 0,1 can merge with 1,2 but don't overlap */
  32 static bool ranges_can_merge(Range *range1, Range *range2)
  33 {
  34     return !(range1->end < range2->begin || range2->end < range1->begin);
  35 }
  36
  37 static void range_merge(Range *range1, Range *range2)
  38 {
  39     if (range1->end < range2->end) {
  40         range1->end = range2->end;
  41     }
  42     if (range1->begin > range2->begin) {
  43         range1->begin = range2->begin;
  44     }
  45 }
  46
  47 static gint range_compare(gconstpointer a, gconstpointer b)
  48 {
  49     Range *ra = (Range *)a, *rb = (Range *)b;
  50     if (ra->begin == rb->begin && ra->end == rb->end) {
  51         return 0;
  52     } else if (range_get_last(ra->begin, ra->end) <
  53                range_get_last(rb->begin, rb->end)) {
  54         return -1;
  55     } else {
  56         return 1;
  57     }
  58 }
  59
  60 GList *range_list_insert(GList *list, Range *data)
  61 {
  62     GList *l, *next = NULL;
  63     Range *r, *nextr;
  64
  65     if (!list) {
  66         list = g_list_insert_sorted(list, data, range_compare);
  67         return list;
  68     }
  69
  70     nextr = data;
  71     l = list;
  72     while (l && l != next && nextr) {
  73         r = l->data;
  74         if (ranges_can_merge(r, nextr)) {
  75             range_merge(r, nextr);
  76             l = g_list_remove_link(l, next);
  77             next = g_list_next(l);
  78             if (next) {
  79                 nextr = next->data;
  80             } else {
  81                 nextr = NULL;
  82             }
  83         } else {
  84             l = g_list_next(l);
  85         }
  86     }
  87
  88     if (!l) {
  89         list = g_list_insert_sorted(list, data, range_compare);
  90     }
  91
  92     return list;
  93 }