qemu/util/range.c
Eric Blake 7c47959d0c qapi: Simplify use of range.h
Calling our function g_list_insert_sorted_merged is a misnomer,
since we are NOT writing a glib function.  Furthermore, we are
making every caller pass the same comparator function of
range_merge(): any caller that would try otherwise would break
in weird ways since our internal call to ranges_can_merge() is
hard-coded to operate only on ranges, rather than paying
attention to the caller's comparator.

Better is to fix things so that callers don't have to care about
our internal comparator, by picking a function name and updating
the parameter type away from a gratuitous use of void*, to make
it obvious that we are operating specifically on a list of ranges
and not a generic list.  Plus, refactoring the code here will
make it easier to plug a memory leak in the next patch.

range_compare() is now internal only, and moves to the .c file.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1464712890-14262-3-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-06-30 15:28:51 +02:00

94 lines
2.4 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"
/*
* Operations on 64 bit address ranges.
* Notes:
* - ranges must not wrap around 0, but can include the last byte ~0x0LL.
* - this can not represent a full 0 to ~0x0LL range.
*/
/* 0,1 can merge with 1,2 but don't overlap */
static bool ranges_can_merge(Range *range1, Range *range2)
{
return !(range1->end < range2->begin || range2->end < range1->begin);
}
static void range_merge(Range *range1, Range *range2)
{
if (range1->end < range2->end) {
range1->end = range2->end;
}
if (range1->begin > range2->begin) {
range1->begin = range2->begin;
}
}
static gint range_compare(gconstpointer a, gconstpointer b)
{
Range *ra = (Range *)a, *rb = (Range *)b;
if (ra->begin == rb->begin && ra->end == rb->end) {
return 0;
} else if (range_get_last(ra->begin, ra->end) <
range_get_last(rb->begin, rb->end)) {
return -1;
} else {
return 1;
}
}
GList *range_list_insert(GList *list, Range *data)
{
GList *l, *next = NULL;
Range *r, *nextr;
if (!list) {
list = g_list_insert_sorted(list, data, range_compare);
return list;
}
nextr = data;
l = list;
while (l && l != next && nextr) {
r = l->data;
if (ranges_can_merge(r, nextr)) {
range_merge(r, nextr);
l = g_list_remove_link(l, next);
next = g_list_next(l);
if (next) {
nextr = next->data;
} else {
nextr = NULL;
}
} else {
l = g_list_next(l);
}
}
if (!l) {
list = g_list_insert_sorted(list, data, range_compare);
}
return list;
}