/*
Copyright (c) 2003, Dan Kranz and Arnold Rom
All rights reserved.

Redistribution and use in source and binary forms, with or
without modification, are permitted provided that the following
conditions are met:

    * Redistributions of source code must retain the above
      copyright notice, this list of conditions and the following
      disclaimer.

    * Redistributions in binary form must reproduce the above
      copyright notice, this list of conditions and the following
      disclaimer in the documentation and/or other materials
      provided with the distribution.

    * The names of its contributors may not be used to endorse or
      promote products derived from this software without specific
      prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <roots.h>

/* ############################################################################# */
/* #                UGROUP (FIRST,LNEXTL,LFRSTL,LFRSTG,NGROUP)                 # */
/* #                ------------------------------------------                 # */
/* #  UGROUP processes the output list generated by UQSORT.                    # */
/* #                                                                           # */
/* #  UGROUP  converts  UQSORT's  output  list  to  a  standard  COLECT  list  # */
/* #  structure. See ROOTS operations COLECT and MCOLCT.                       # */
/* #                                                                           # */
/* #  The arguments are as follows:                                            # */
/* #                                                                           # */
/* #  FIRST,LNEXTL,LFRSTL - are input to UGROUP.  these parameters are output  # */
/* #                        from UQSORT.  See ROOTS operation UQSORT.          # */
/* #                                                                           # */
/* #  LFRSTG,NGROUP       - are  output  from  UGROUP.  In particular, UGROUP  # */
/* #                        severs  the input chain FIRST,LNEXTL.  Each input  # */
/* #                        member  yields  a  distinct  output group.  Input  # */
/* #                        clone  sublists  LFRSTL(L),LNEXTL  are  linked to  # */
/* #                        their respective ancestors.                        # */
/* #                                                                           # */
/* #  NGROUP              - is  determined  by  UGROUP  and  equals the total  # */
/* #                        number  of  output groups; i.e.  LFRSTG(g),LNEXTL  # */
/* #                        defines  a  distinct  sublist for all g's ranging  # */
/* #                        from 1 to NGROUP.                                  # */
/* #                                                                           # */
/* #  UQSORT/UGROUP    can    be    used    instead    of    the    sequence:  # */
/* #  CHSORT/LIST1/MCOLCT.                                                     # */
/* ############################################################################# */


/* small internal routines */

static void sos(void) {RootsSOS("ugroup sos exit\n"); abort();}

void ugroup(
                       long           *first,
                       unsigned short *lnextl,
                       unsigned short *lfrstl,
                       unsigned short *lfrstg,
                       long           *ngroup
                       )

/* --------------------------------------------------------- */
{       /* ugroup START */
/* --------------------------------------------------------- */

/*      local data */

        unsigned short q,group=0,next;
        long guard=MAXLIN;

        --lnextl; --lfrstl; --lfrstg;

        for(q=(unsigned short)(*first); q>0; q=next)
        {
        if(!guard--)sos();
        group++;
        *(lfrstg+group)=q;
        next=*(lnextl+q);
        *(lnextl+q)=*(lfrstl+q);
        }
        *ngroup=group;
        return;
/* --------------------------------------------------------- */
}       /* ugroup END */
/* --------------------------------------------------------- */