[Xen-devel] question on xenolinux use of ffs()

[ron minnich <rminnich@xxxxxxxx>]

        while ( (l1i = ffs(l1)) != 0 )
        {
            l1i--;
            l1 &= ~(1 << l1i);
        
            l2 = s->evtchn_pending[l1i] & ~s->evtchn_mask[l1i];
            while ( (l2i = ffs(l2)) != 0 )
            {
                l2i--;


from evtchn.c

This seems to assume that ffs is 1-relative in the bit numbers. My testing 
shows it is 0-relative, and the manual bears me out. 

Has this code changed in the latest, am I missing something, or ...

For Plan 9 I changed it to:

        while ( (l1i = ffs(l1)) >= 0 )
        {
            l1 &= ~(1 << l1i);
        
            l2 = s->evtchn_pending[l1i] & ~s->evtchn_mask[l1i];
            while ( (l2i = ffs(l2)) >= 0 )
            {

ron



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