mirror of
https://gitlab.com/qemu-project/qemu
synced 2024-09-06 01:43:39 +00:00
![Markus Armbruster](/assets/img/avatar_default.png)
Range represents a range as follows. Member @start is the inclusive lower bound, member @end is the exclusive upper bound. Zero @end is special: if @start is also zero, the range is empty, else @end is to be interpreted as 2^64. No other empty ranges may occur. The range [0,2^64-1] cannot be represented. If you try to create it with range_set_bounds1(), you get the empty range instead. If you try to create it with range_set_bounds() or range_extend(), assertions fail. Before range_set_bounds() existed, the open-coded creation usually got you the empty range instead. Open deathtrap. Moreover, the code dealing with the janus-faced @end is too clever by half. Dumb this down to a more pedestrian representation: members @lob and @upb are inclusive lower and upper bounds. The empty range is encoded as @lob = 1, @upb = 0. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
/*
|
|
* QEMU 64-bit address ranges
|
|
*
|
|
* Copyright (c) 2015-2016 Red Hat, Inc.
|
|
*
|
|
* This library is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2 of the License, or (at your option) any later version.
|
|
*
|
|
* This library is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public
|
|
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
|
|
*
|
|
*/
|
|
|
|
#include "qemu/osdep.h"
|
|
#include "qemu/range.h"
|
|
|
|
/*
|
|
* Return -1 if @a < @b, 1 @a > @b, and 0 if they touch or overlap.
|
|
* Both @a and @b must not be empty.
|
|
*/
|
|
static inline int range_compare(Range *a, Range *b)
|
|
{
|
|
assert(!range_is_empty(a) && !range_is_empty(b));
|
|
|
|
/* Careful, avoid wraparound */
|
|
if (b->lob && b->lob - 1 > a->upb) {
|
|
return -1;
|
|
}
|
|
if (a->lob && a->lob - 1 > b->upb) {
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Insert @data into @list of ranges; caller no longer owns @data */
|
|
GList *range_list_insert(GList *list, Range *data)
|
|
{
|
|
GList *l;
|
|
|
|
assert(!range_is_empty(data));
|
|
|
|
/* Skip all list elements strictly less than data */
|
|
for (l = list; l && range_compare(l->data, data) < 0; l = l->next) {
|
|
}
|
|
|
|
if (!l || range_compare(l->data, data) > 0) {
|
|
/* Rest of the list (if any) is strictly greater than @data */
|
|
return g_list_insert_before(list, l, data);
|
|
}
|
|
|
|
/* Current list element overlaps @data, merge the two */
|
|
range_extend(l->data, data);
|
|
g_free(data);
|
|
|
|
/* Merge any subsequent list elements that now also overlap */
|
|
while (l->next && range_compare(l->data, l->next->data) == 0) {
|
|
GList *new_l;
|
|
|
|
range_extend(l->data, l->next->data);
|
|
g_free(l->next->data);
|
|
new_l = g_list_delete_link(list, l->next);
|
|
assert(new_l == list);
|
|
}
|
|
|
|
return list;
|
|
}
|