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

Cédric Le Goater posted 42 patches 5 months ago

Diff against v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v1 v2 v2 v2
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Maintainers: Yi Liu <yi.l.liu@intel.com>, Eric Auger <eric.auger@redhat.com>, Zhenzhong Duan <zhenzhong.duan@intel.com>, "Michael S. Tsirkin" <mst@redhat.com>, Jason Wang <jasowang@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, Alex Williamson <alex.williamson@redhat.com>, "Cédric Le Goater" <clg@redhat.com>, Nicholas Piggin <npiggin@gmail.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Peter Xu <peterx@redhat.com>, David Hildenbrand <david@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>

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

Posted by Cédric Le Goater 5 months ago

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(+)

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.
-- 
2.45.2