/*! @file zsnode_dfs.c

 * \brief Determines the union of row structures of columns within the relaxed node

 *

 * 

 * -- SuperLU routine (version 2.0) --

 * Univ. of California Berkeley, Xerox Palo Alto Research Center,

 * and Lawrence Berkeley National Lab.

 * November 15, 1997

 *

 * Copyright (c) 1994 by Xerox Corporation.  All rights reserved.

 *

 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY

 * EXPRESSED OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.

 * 

 * Permission is hereby granted to use or copy this program for any

 * purpose, provided the above notices are retained on all copies.

 * Permission to modify the code and to distribute modified code is

 * granted, provided the above notices are retained, and a notice that

 * the code was modified is included with the above copyright notice.

 * 

 */

#include "slu_zdefs.h"

/*! \brief

 *

 * 

 * Purpose

 * =======

 *    zsnode_dfs() - Determine the union of the row structures of those 

 *    columns within the relaxed snode.

 *    Note: The relaxed snodes are leaves of the supernodal etree, therefore, 

 *    the portion outside the rectangular supernode must be zero.

 *

 * Return value

 * ============

 *     0   success;

 *    >0   number of bytes allocated when run out of memory.

 * 

 */

int

zsnode_dfs (

	   const int  jcol,	    /* in - start of the supernode */

	   const int  kcol, 	    /* in - end of the supernode */

	   const int  *asub,        /* in */

	   const int  *xa_begin,    /* in */

	   const int  *xa_end,      /* in */

	   int        *xprune,      /* out */

	   int        *marker,      /* modified */

	   GlobalLU_t *Glu          /* modified */

	   )

{

    register int i, k, ifrom, ito, nextl, new_next;

    int          nsuper, krow, kmark, mem_error;

    int          *xsup, *supno;

    int          *lsub, *xlsub;

    int          nzlmax;

    xsup    = Glu->xsup;

    supno   = Glu->supno;

    lsub    = Glu->lsub;

    xlsub   = Glu->xlsub;

    nzlmax  = Glu->nzlmax;

    nsuper = ++supno[jcol];	/* Next available supernode number */

    nextl = xlsub[jcol];

    for (i = jcol; i <= kcol; i++) {

	/* For each nonzero in A[*,i] */

	for (k = xa_begin[i]; k < xa_end[i]; k++) {	

	    krow = asub[k];

	    kmark = marker[krow];

	    if ( kmark != kcol ) { /* First time visit krow */

		marker[krow] = kcol;

		lsub[nextl++] = krow;

		if ( nextl >= nzlmax ) {

		    if ( mem_error = zLUMemXpand(jcol, nextl, LSUB, &nzlmax, Glu) )

			return (mem_error);

		    lsub = Glu->lsub;

		}

	    }

    	}

	supno[i] = nsuper;

    }

    /* Supernode > 1, then make a copy of the subscripts for pruning */

    if ( jcol < kcol ) {

	new_next = nextl + (nextl - xlsub[jcol]);

	while ( new_next > nzlmax ) {

	    if ( mem_error = zLUMemXpand(jcol, nextl, LSUB, &nzlmax, Glu) )

		return (mem_error);

	    lsub = Glu->lsub;

	}

	ito = nextl;

	for (ifrom = xlsub[jcol]; ifrom < nextl; )

	    lsub[ito++] = lsub[ifrom++];	

        for (i = jcol+1; i <= kcol; i++) xlsub[i] = nextl;

	nextl = ito;

    }

    xsup[nsuper+1] = kcol + 1;

    supno[kcol+1]  = nsuper;

    xprune[kcol]   = nextl;

    xlsub[kcol+1]  = nextl;

    return 0;

}