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range: Introduce range_get_last_bit() 

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>
This commit is contained in:
Zhenzhong Duan 2024-06-05 16:30:31 +08:00 committed by Cédric Le Goater
parent 9005f92844
commit 6f274444c5
1 changed files with 11 additions and 0 deletions
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11
include/qemu/range.h
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@ -20,6 +20,8 @@
#ifndef QEMU_RANGE_H #ifndef QEMU_RANGE_H
#define QEMU_RANGE_H #define QEMU_RANGE_H
#include "qemu/bitops.h"
/* /*
* Operations on 64 bit address ranges. * Operations on 64 bit address ranges.
* Notes: * Notes:
@ -217,6 +219,15 @@ static inline int ranges_overlap(uint64_t first1, uint64_t len1,
return !(last2 < first1 || last1 < first2); 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. * Return -1 if @a < @b, 1 @a > @b, and 0 if they touch or overlap.
* Both @a and @b must not be empty. * Both @a and @b must not be empty.