>-----Original Message-----
>From: Cédric Le Goater <c...@redhat.com>
>Subject: Re: [PATCH v3 06/19] range: Introduce range_get_last_bit()
>
>On 4/30/24 11:58, Duan, Zhenzhong wrote:
>>
>>
>>> -----Original Message-----
>>> From: Cédric Le Goater <c...@redhat.com>
>>> Subject: Re: [PATCH v3 06/19] range: Introduce range_get_last_bit()
>>>
>>> On 4/29/24 08:50, Zhenzhong Duan wrote:
>>>> 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 <c...@redhat.com>
>>>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
>>>> ---
>>>> include/qemu/range.h | 11 +++++++++++
>>>> 1 file changed, 11 insertions(+)
>>>>
>>>> diff --git a/include/qemu/range.h b/include/qemu/range.h
>>>> index 205e1da76d..8e05bc1d9f 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) || !range->upb) {
>>>> + return -1;
>>>> + }
>>>> + return find_last_bit(&range->upb, sizeof(range->upb));
>>>
>>> This breaks builds on 32-bit host systems.
>>
>> Oh, I missed 32bit build. Thanks, will fix.
>
>This should provide the same result ?
>
> return 63 - clz64(range->upb);
Yes, I tried 32bit and 64bit, it works. Will use it, thanks for suggestion.
BRs.
Zhenzhong
