Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ndb.h>

/*
 *  reorder the tuple to put x's line first in the entry and x fitst in its line
 */
Ndbtuple*
ndbreorder(Ndbtuple *t, Ndbtuple *x)
{
        Ndbtuple *nt;
        Ndbtuple *last, *prev;

        /* if x is first, we're done */
        if(x == t)
                return t;

        /* find end of x's line */
        for(last = x; last->line == last->entry; last = last->line)
                ;

        /* rotate to make this line first */
        if(last->line != t){

                /* detach this line and everything after it from the entry */
                for(nt = t; nt->entry != last->line; nt = nt->entry)
                        ;
                nt->entry = nil;
        
                /* switch */
                for(nt = last; nt->entry != nil; nt = nt->entry)
                        ;
                nt->entry = t;
        }

        /* rotate line to make x first */
        if(x != last->line){

                /* find entry before x */
                for(prev = last; prev->line != x; prev = prev->line);
                        ;

                /* detach line */
                nt = last->entry;
                last->entry = last->line;

                /* reattach */
                prev->entry = nt;
        }

        return x;
}