util/range.c

   1 /*
   2  * QEMU 64-bit address ranges
   3  *
   4  * Copyright (c) 2015-2016 Red Hat, Inc.
   5  *
   6  * This program 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 program 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  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "qemu/osdep.h"
  21 #include "qemu/range.h"
  22
  23 int range_compare(Range *a, Range *b)
  24 {
  25     assert(!range_is_empty(a) && !range_is_empty(b));
  26
  27     /* Careful, avoid wraparound */
  28     if (b->lob && b->lob - 1 > a->upb) {
  29         return -1;
  30     }
  31     if (a->lob && a->lob - 1 > b->upb) {
  32         return 1;
  33     }
  34     return 0;
  35 }
  36
  37 /* Insert @data into @list of ranges; caller no longer owns @data */
  38 GList *range_list_insert(GList *list, Range *data)
  39 {
  40     GList *l;
  41
  42     assert(!range_is_empty(data));
  43
  44     /* Skip all list elements strictly less than data */
  45     for (l = list; l && range_compare(l->data, data) < 0; l = l->next) {
  46     }
  47
  48     if (!l || range_compare(l->data, data) > 0) {
  49         /* Rest of the list (if any) is strictly greater than @data */
  50         return g_list_insert_before(list, l, data);
  51     }
  52
  53     /* Current list element overlaps @data, merge the two */
  54     range_extend(l->data, data);
  55     g_free(data);
  56
  57     /* Merge any subsequent list elements that now also overlap */
  58     while (l->next && range_compare(l->data, l->next->data) == 0) {
  59         GList *new_l;
  60
  61         range_extend(l->data, l->next->data);
  62         g_free(l->next->data);
  63         new_l = g_list_delete_link(list, l->next);
  64         assert(new_l == list);
  65     }
  66
  67     return list;
  68 }
  69
  70 static inline
  71 GList *append_new_range(GList *list, uint64_t lob, uint64_t upb)
  72 {
  73     Range *new = g_new0(Range, 1);
  74
  75     range_set_bounds(new, lob, upb);
  76     return g_list_append(list, new);
  77 }
  78
  79
  80 void range_inverse_array(GList *in, GList **rev,
  81                          uint64_t low, uint64_t high)
  82 {
  83     Range *r, *rn;
  84     GList *l = in, *out = *rev;
  85
  86     for (l = in; l && range_upb(l->data) < low; l = l->next) {
  87         continue;
  88     }
  89
  90     if (!l) {
  91         out = append_new_range(out, low, high);
  92         goto exit;
  93     }
  94     r = (Range *)l->data;
  95
  96     /* first range lob is greater than min, insert a first range */
  97     if (range_lob(r) > low) {
  98         out = append_new_range(out, low, MIN(range_lob(r) - 1, high));
  99     }
 100
 101     /* insert a range inbetween each original range until we reach high */
 102     for (; l->next; l = l->next) {
 103         r = (Range *)l->data;
 104         rn = (Range *)l->next->data;
 105         if (range_lob(r) >= high) {
 106             goto exit;
 107         }
 108         if (range_compare(r, rn)) {
 109             out = append_new_range(out, range_upb(r) + 1,
 110                                    MIN(range_lob(rn) - 1, high));
 111         }
 112     }
 113
 114     /* last range */
 115     r = (Range *)l->data;
 116
 117     /* last range upb is less than max, insert a last range */
 118     if (range_upb(r) <  high) {
 119         out = append_new_range(out, range_upb(r) + 1, high);
 120     }
 121 exit:
 122     *rev = out;
 123 }