1 files changed, 91 insertions, 12 deletions

diff --git a/include/qemu/range.h b/include/qemu/range.h
index 3970f00089..f28f0c1825 100644
--- a/include/qemu/range.h
+++ b/include/qemu/range.h
@@ -26,32 +26,111 @@
 /*
  * 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.
+ * - Ranges must not wrap around 0, but can include UINT64_MAX.
  */
 
-/* A structure representing a range of addresses. */
 struct Range {
-    uint64_t begin; /* First byte of the range, or 0 if empty. */
-    uint64_t end;   /* 1 + the last byte. 0 if range empty or ends at ~0x0LL. */
+    /*
+     * Do not access members directly, use the functions!
+     * A non-empty range has @lob <= @upb.
+     * An empty range has @lob == @upb + 1.
+     */
+    uint64_t lob;        /* inclusive lower bound */
+    uint64_t upb;        /* inclusive upper bound */
 };
 
+static inline void range_invariant(Range *range)
+{
+    assert(range->lob <= range->upb || range->lob == range->upb + 1);
+}
+
+/* Compound literal encoding the empty range */
+#define range_empty ((Range){ .lob = 1, .upb = 0 })
+
+/* Is @range empty? */
+static inline bool range_is_empty(Range *range)
+{
+    range_invariant(range);
+    return range->lob > range->upb;
+}
+
+/* Does @range contain @val? */
+static inline bool range_contains(Range *range, uint64_t val)
+{
+    return val >= range->lob && val <= range->upb;
+}
+
+/* Initialize @range to the empty range */
+static inline void range_make_empty(Range *range)
+{
+    *range = range_empty;
+    assert(range_is_empty(range));
+}
+
+/*
+ * Initialize @range to span the interval [@lob,@upb].
+ * Both bounds are inclusive.
+ * The interval must not be empty, i.e. @lob must be less than or
+ * equal @upb.
+ */
+static inline void range_set_bounds(Range *range, uint64_t lob, uint64_t upb)
+{
+    range->lob = lob;
+    range->upb = upb;
+    assert(!range_is_empty(range));
+}
+
+/*
+ * Initialize @range to span the interval [@lob,@upb_plus1).
+ * The lower bound is inclusive, the upper bound is exclusive.
+ * Zero @upb_plus1 is special: if @lob is also zero, set @range to the
+ * empty range.  Else, set @range to [@lob,UINT64_MAX].
+ */
+static inline void range_set_bounds1(Range *range,
+                                     uint64_t lob, uint64_t upb_plus1)
+{
+    if (!lob && !upb_plus1) {
+        *range = range_empty;
+    } else {
+        range->lob = lob;
+        range->upb = upb_plus1 - 1;
+    }
+    range_invariant(range);
+}
+
+/* Return @range's lower bound.  @range must not be empty. */
+static inline uint64_t range_lob(Range *range)
+{
+    assert(!range_is_empty(range));
+    return range->lob;
+}
+
+/* Return @range's upper bound.  @range must not be empty. */
+static inline uint64_t range_upb(Range *range)
+{
+    assert(!range_is_empty(range));
+    return range->upb;
+}
+
+/*
+ * Extend @range to the smallest interval that includes @extend_by, too.
+ */
 static inline void range_extend(Range *range, Range *extend_by)
 {
-    if (!extend_by->begin && !extend_by->end) {
+    if (range_is_empty(extend_by)) {
         return;
     }
-    if (!range->begin && !range->end) {
+    if (range_is_empty(range)) {
         *range = *extend_by;
         return;
     }
-    if (range->begin > extend_by->begin) {
-        range->begin = extend_by->begin;
+    if (range->lob > extend_by->lob) {
+        range->lob = extend_by->lob;
     }
-    /* Compare last byte in case region ends at ~0x0LL */
-    if (range->end - 1 < extend_by->end - 1) {
-        range->end = extend_by->end;
+    if (range->upb < extend_by->upb) {
+        range->upb = extend_by->upb;
     }
+    range_invariant(range);
 }
 
 /* Get last byte of a range from offset + length.