This helper reverses an array of regions, turning original
regions into holes and original holes into actual regions,
covering the whole UINT64_MAX span.
Signed-off-by: Eric Auger <eric.au...@redhat.com>
---
v1 -> v2:
- Move range_inverse_array description comment in the header
- Take low/high params
---
include/qemu/range.h | 8 ++++++++
util/range.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
diff --git a/include/qemu/range.h b/include/qemu/range.h
index 7e2b1cc447..2b59e3bf0c 100644
--- a/include/qemu/range.h
+++ b/include/qemu/range.h
@@ -219,4 +219,12 @@ static inline int ranges_overlap(uint64_t first1, uint64_t
len1,
GList *range_list_insert(GList *list, Range *data);
+/*
+ * Inverse an array of sorted ranges over the [low, high] span, ie.
+ * original ranges becomes holes in the newly allocated inv_ranges
+ */
+void range_inverse_array(uint32_t nr_ranges, Range *ranges,
+ uint32_t *nr_inv_ranges, Range **inv_ranges,
+ uint64_t low, uint64_t high);
+
#endif
diff --git a/util/range.c b/util/range.c
index 098d9d2dc0..4baeb588cc 100644
--- a/util/range.c
+++ b/util/range.c
@@ -70,3 +70,48 @@ GList *range_list_insert(GList *list, Range *data)
return list;
}
+
+void range_inverse_array(uint32_t nr_ranges, Range *ranges,
+ uint32_t *nr_inv_ranges, Range **inv_ranges,
+ uint64_t low, uint64_t high)
+{
+ Range *resv;
+ int i = 0, j = 0;
+
+ resv = g_malloc0_n(nr_ranges + 1, sizeof(Range));
+
+ for (; j < nr_ranges && (range_upb(&ranges[j]) < low); j++) {
+ continue; /* skip all ranges below mon */
+ }
+
+ if (j == nr_ranges) {
+ range_set_bounds(&resv[i++], low, high);
+ goto realloc;
+ }
+
+ /* first range lob is greater than min, insert a first range */
+ if (range_lob(&ranges[j]) > low) {
+ range_set_bounds(&resv[i++], low,
+ MIN(range_lob(&ranges[j]) - 1, high));
+ }
+
+ /* insert a range inbetween each original range until we reach max */
+ for (; j < nr_ranges - 1; j++) {
+ if (range_lob(&ranges[j]) >= high) {
+ goto realloc;
+ }
+ if (range_compare(&ranges[j], &ranges[j + 1])) {
+ range_set_bounds(&resv[i++], range_upb(&ranges[j]) + 1,
+ MIN(range_lob(&ranges[j + 1]) - 1, high));
+ }
+ }
+ /* last range upb is less than max, insert a last range */
+ if (range_upb(&ranges[j]) < high) {
+ range_set_bounds(&resv[i++],
+ range_upb(&ranges[j]) + 1, high);
+ }
+realloc:
+ *nr_inv_ranges = i;
+ resv = g_realloc(resv, i * sizeof(Range));
+ *inv_ranges = resv;
+}
--
2.41.0
