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[PULL,05/42] range: Introduce range_get_last_bit()

Message ID 20240624212456.350919-6-clg@redhat.com (mailing list archive)
State New, archived
Headers show
Series [PULL,01/42] backends: Introduce HostIOMMUDevice abstract | expand

Commit Message

Cédric Le Goater June 24, 2024, 9:24 p.m. UTC 
From: Zhenzhong Duan <zhenzhong.duan@intel.com>

This helper get the highest 1 bit position of the upper bound.

If the range is empty or upper bound is zero, -1 is returned.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/qemu/range.h | 11 +++++++++++
 1 file changed, 11 insertions(+)
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Patch

diff --git a/include/qemu/range.h b/include/qemu/range.h
index 205e1da76dc5b29327f590b8293a826ced63c25d..4ce694a398311a32e9b5e3ca97aed97c90c0ae09 100644
--- a/include/qemu/range.h
+++ b/include/qemu/range.h
@@ -20,6 +20,8 @@ 
 #ifndef QEMU_RANGE_H
 #define QEMU_RANGE_H
 
+#include "qemu/bitops.h"
+
 /*
  * Operations on 64 bit address ranges.
  * Notes:
@@ -217,6 +219,15 @@  static inline int ranges_overlap(uint64_t first1, uint64_t len1,
     return !(last2 < first1 || last1 < first2);
 }
 
+/* Get highest non-zero bit position of a range */
+static inline int range_get_last_bit(Range *range)
+{
+    if (range_is_empty(range)) {
+        return -1;
+    }
+    return 63 - clz64(range->upb);
+}
+
 /*
  * Return -1 if @a < @b, 1 @a > @b, and 0 if they touch or overlap.
  * Both @a and @b must not be empty.