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/*! @file ilu_zsnode_dfs.c
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 * \brief Determines the union of row structures of columns within the relaxed node
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 *
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 * 
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 * -- SuperLU routine (version 4.0) --
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 * Lawrence Berkeley National Laboratory
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 * June 30, 2009
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 * 
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 */
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#include "slu_zdefs.h"
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/*! \brief
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 *
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 * 
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 * Purpose
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 * =======
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 *    ilu_zsnode_dfs() - Determine the union of the row structures of those
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 *    columns within the relaxed snode.
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 *    Note: The relaxed snodes are leaves of the supernodal etree, therefore,
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 *    the portion outside the rectangular supernode must be zero.
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 *
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 * Return value
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 * ============
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 *     0   success;
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 *    >0   number of bytes allocated when run out of memory.
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 * 
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 */
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int
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ilu_zsnode_dfs(
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	   const int  jcol,	    /* in - start of the supernode */
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	   const int  kcol,	    /* in - end of the supernode */
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	   const int  *asub,	    /* in */
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	   const int  *xa_begin,    /* in */
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	   const int  *xa_end,	    /* in */
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	   int	      *marker,	    /* modified */
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	   GlobalLU_t *Glu	    /* modified */
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	   )
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{
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    register int i, k, nextl;
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    int 	 nsuper, krow, kmark, mem_error;
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    int 	 *xsup, *supno;
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    int 	 *lsub, *xlsub;
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    int 	 nzlmax;
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    xsup    = Glu->xsup;
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    supno   = Glu->supno;
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    lsub    = Glu->lsub;
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    xlsub   = Glu->xlsub;
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    nzlmax  = Glu->nzlmax;
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    nsuper = ++supno[jcol];	/* Next available supernode number */
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    nextl = xlsub[jcol];
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    for (i = jcol; i <= kcol; i++)
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    {
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	/* For each nonzero in A[*,i] */
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	for (k = xa_begin[i]; k < xa_end[i]; k++)
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	{
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	    krow = asub[k];
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	    kmark = marker[krow];
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	    if ( kmark != kcol )
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	    { /* First time visit krow */
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		marker[krow] = kcol;
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		lsub[nextl++] = krow;
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		if ( nextl >= nzlmax )
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		{
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		    if ( (mem_error = zLUMemXpand(jcol, nextl, LSUB, &nzlmax,
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			    Glu)) != 0)
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			return (mem_error);
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		    lsub = Glu->lsub;
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		}
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	    }
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	}
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	supno[i] = nsuper;
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    }
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    /* Supernode > 1 */
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    if ( jcol < kcol )
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	for (i = jcol+1; i <= kcol; i++) xlsub[i] = nextl;
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    xsup[nsuper+1] = kcol + 1;
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    supno[kcol+1]  = nsuper;
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    xlsub[kcol+1]  = nextl;
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    return 0;
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}