On 07/03/2012 01:23 PM, Blue Swirl wrote: >> + >> +static inline int64_t round2pow2(int64_t value)
round up or down?
>> +{
>> + while (!is_power_of_2(value)) {
>> + value &= ~(1 << (ffs(value) - 1));
>
> ffs() only uses 'int', not int64_t. ffsl() is not universally available.
>
>> + }
>> + return value;
>> +}
Not to mention that iterating one bit at a time is inefficient. We
already gave you several more efficient solutions; my favorite being:
static inline int64_t pow2floor(int64_t value)
{
if (!is_power_of_2(value)) {
value = 0x8000000000000000ULL >> clz64(value);
}
return value;
}
since clz64() is already part of qemu sources.
--
Eric Blake ebl...@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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