LXR qemu/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 * Return -1 if @a < @b, 1 @a > @b, and 0 if they touch or overlap.
  26 * Both @a and @b must not be empty.
  27 */
  28static inline int range_compare(Range *a, Range *b)
  29{
  30    assert(!range_is_empty(a) && !range_is_empty(b));
  31
  32    /* Careful, avoid wraparound */
  33    if (b->lob && b->lob - 1 > a->upb) {
  34        return -1;
  35    }
  36    if (a->lob && a->lob - 1 > b->upb) {
  37        return 1;
  38    }
  39    return 0;
  40}
  41
  42/* Insert @data into @list of ranges; caller no longer owns @data */
  43GList *range_list_insert(GList *list, Range *data)
  44{
  45    GList *l;
  46
  47    assert(!range_is_empty(data));
  48
  49    /* Skip all list elements strictly less than data */
  50    for (l = list; l && range_compare(l->data, data) < 0; l = l->next) {
  51    }
  52
  53    if (!l || range_compare(l->data, data) > 0) {
  54        /* Rest of the list (if any) is strictly greater than @data */
  55        return g_list_insert_before(list, l, data);
  56    }
  57
  58    /* Current list element overlaps @data, merge the two */
  59    range_extend(l->data, data);
  60    g_free(data);
  61
  62    /* Merge any subsequent list elements that now also overlap */
  63    while (l->next && range_compare(l->data, l->next->data) == 0) {
  64        GList *new_l;
  65
  66        range_extend(l->data, l->next->data);
  67        g_free(l->next->data);
  68        new_l = g_list_delete_link(list, l->next);
  69        assert(new_l == list);
  70    }
  71
  72    return list;
  73}
  74