/* LIBDGL -- a Directed Graph Library implementation
 * Copyright (C) 2002 Roberto Micarelli
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*
 * best view with tabstop=4
 */

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>

#define DGL_V2 1

#include "type.h"
#include "tree.h"
#include "graph.h"
#include "graph_v1.h"
#if defined(DGL_V2)
#include "graph_v2.h"
#endif
#include "helpers.h"


void dglResetStats( dglGraph_s * pgraph )
{
#ifdef DGL_STATS
	pgraph->clkAddEdge = 0;
	pgraph->cAddEdge = 0;
	pgraph->clkNodeTree = 0;
	pgraph->cNodeTree = 0;
#endif
}

int dglInitialize(dglGraph_s * pGraph, dglByte_t Version, dglInt32_t NodeAttrSize, dglInt32_t EdgeAttrSize, dglInt32_t * pOpaqueSet)
{
	if ( pGraph == NULL ) {
		return -DGL_ERR_BadArgument;
	}
	switch( Version )
	{
	case 1:
#ifdef DGL_V2
	case 2:
	case 3:
#endif
		memset( pGraph , 0 , sizeof( dglGraph_s ) );
		/*
	   	 * round attr size to the upper multiple of dglInt32_t size
	 	 */
		if ( NodeAttrSize % sizeof(dglInt32_t) ) NodeAttrSize += ( sizeof(dglInt32_t) - (NodeAttrSize % sizeof(dglInt32_t)) );
		if ( EdgeAttrSize % sizeof(dglInt32_t) ) EdgeAttrSize += ( sizeof(dglInt32_t) - (EdgeAttrSize % sizeof(dglInt32_t)) );
		pGraph->Version  = Version;
		pGraph->NodeAttrSize = NodeAttrSize;
		pGraph->EdgeAttrSize = EdgeAttrSize;
		if ( pOpaqueSet ) memcpy( & pGraph->aOpaqueSet , pOpaqueSet , sizeof( dglInt32_t ) * 16 );
#ifdef DGL_ENDIAN_BIG
		pGraph->Endian = DGL_ENDIAN_BIG;
#else
		pGraph->Endian = DGL_ENDIAN_LITTLE;
#endif
	}
	switch( Version ) {
	case 1:
		if ( dgl_initialize_V1(pGraph) < 0 ) {
			return -pGraph->iErrno;
		}
		else return 0;
#ifdef DGL_V2
	case 2:
	case 3:
		if ( dgl_initialize_V2(pGraph) < 0 ) {
			return -pGraph->iErrno;
		}
		else return 0;
#endif
	}
	pGraph->iErrno = DGL_ERR_VersionNotSupported;
	return -pGraph->iErrno;
}

int dglRelease( dglGraph_s * pGraph )
{
	switch( pGraph->Version ) {
	case 1: return dgl_release_V1(pGraph);
#ifdef DGL_V2
	case 2:
	case 3: return dgl_release_V2(pGraph);
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}

int dglUnflatten( dglGraph_s * pGraph )
{
	switch( pGraph->Version ) {
	case 1: return dgl_unflatten_V1(pGraph);
#ifdef DGL_V2
	case 2:
	case 3: return dgl_unflatten_V2(pGraph);
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}


int dglFlatten( dglGraph_s * pGraph )
{
	switch( pGraph->Version ) {
	case 1: return dgl_flatten_V1(pGraph);
#ifdef DGL_V2
	case 2:
	case 3: return dgl_flatten_V2(pGraph);
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}


dglInt32_t * dglGetNode(dglGraph_s * pGraph , dglInt32_t nNodeId)
{
	switch( pGraph->Version ) {
	case 1: return dgl_get_node_V1(pGraph, nNodeId);
#ifdef DGL_V2
	case 2:
	case 3: return dgl_get_node_V2(pGraph, nNodeId);
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}

dglInt32_t *	dglNodeGet_OutEdgeset(dglGraph_s * pGraph, dglInt32_t * pnNode)
{
	if ( pnNode) {
		switch( pGraph->Version ) {
		case 1: return dgl_getnode_outedgeset_V1(pGraph, pnNode);
#ifdef DGL_V2
		case 2:
		case 3: return dgl_getnode_outedgeset_V2(pGraph, pnNode);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return NULL;
	}
	return NULL;
}

dglInt32_t *	dglNodeGet_InEdgeset(dglGraph_s * pGraph, dglInt32_t * pnNode)
{
	if ( pnNode) {
		switch( pGraph->Version ) {
		case 1: pGraph->iErrno = DGL_ERR_NotSupported; return NULL;
#ifdef DGL_V2
		case 2:
		case 3: return dgl_getnode_inedgeset_V2(pGraph, pnNode);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return NULL;
	}
	return NULL;
}



/*
 * Given that node id can be negative, only iErrno can report a error,
 * thus it is initialized to zero
 */
dglInt32_t	dglNodeGet_Id(dglGraph_s * pGraph, dglInt32_t * pnNode)
{
	pGraph->iErrno = 0;
	if (pnNode) {
		switch( pGraph->Version ) {
		case 1: return DGL_NODE_ID_v1(pnNode);
#ifdef DGL_V2
		case 2:
		case 3: return DGL_NODE_ID_v2(pnNode);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}


dglInt32_t	dglNodeGet_Status(dglGraph_s * pGraph, dglInt32_t * pnNode)
{
	pGraph->iErrno = 0;
	if (pnNode) {
		switch( pGraph->Version ) {
		case 1: return DGL_NODE_STATUS_v1(pnNode);
#ifdef DGL_V2
		case 2:
		case 3: return DGL_NODE_STATUS_v2(pnNode);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}


dglInt32_t *	dglNodeGet_Attr(dglGraph_s * pGraph, dglInt32_t * pnNode)
{
	if ( pnNode) {
		switch( pGraph->Version ) {
		case 1: return DGL_NODE_ATTR_PTR_v1(pnNode);
#ifdef DGL_V2
		case 2:
		case 3: return DGL_NODE_ATTR_PTR_v2(pnNode);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return NULL;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return NULL;
}


void dglNodeSet_Attr(dglGraph_s * pGraph, dglInt32_t * pnNode, dglInt32_t * pnAttr)
{
	if ( pnNode) {
		switch( pGraph->Version ) {
		case 1: memcpy(DGL_NODE_ATTR_PTR_v1(pnNode), pnAttr, pGraph->NodeAttrSize);
				return;
#ifdef DGL_V2
		case 2:
		case 3: memcpy(DGL_NODE_ATTR_PTR_v2(pnNode), pnAttr, pGraph->NodeAttrSize);
				return;
#endif
		}
		return;
	}
	return;
}

int dglNodeGet_InDegree( dglGraph_s * pGraph, dglInt32_t * pnNode )
{
#ifdef DGL_V2
	dglInt32_t * pinedgeset;
#endif

	pGraph->iErrno = 0;
	if ( pnNode) {
		switch( pGraph->Version ) {
		case 1:
				pGraph->iErrno = DGL_ERR_NotSupported;
				return 0;
#ifdef DGL_V2
		case 2:
				if ( DGL_NODE_STATUS_v2(pnNode) & DGL_NS_ALONE ) return 0;
				pinedgeset = dglNodeGet_InEdgeset(pGraph, pnNode);
				if ( pinedgeset ) return DGL_EDGESET_EDGECOUNT_v2(pinedgeset);
				return 0;
		case 3:
				return dglNodeGet_Valence(pGraph, pnNode);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}


int dglNodeGet_OutDegree( dglGraph_s * pGraph, dglInt32_t * pnNode )
{
	dglInt32_t * poutedgeset;

	pGraph->iErrno = 0;
	if ( pnNode) {
		switch( pGraph->Version ) {
		case 1:
				if ( DGL_NODE_STATUS_v1(pnNode) & DGL_NS_ALONE ) return 0;
				poutedgeset = dglNodeGet_OutEdgeset(pGraph, pnNode);
				if ( poutedgeset ) return DGL_EDGESET_EDGECOUNT_v1(poutedgeset);
				return 0;
#ifdef DGL_V2
		case 2:
				if ( DGL_NODE_STATUS_v2(pnNode) & DGL_NS_ALONE ) return 0;
				poutedgeset = dglNodeGet_OutEdgeset(pGraph, pnNode);
				if ( poutedgeset ) return DGL_EDGESET_EDGECOUNT_v2(poutedgeset);
				return 0;
		case 3:
				return dglNodeGet_Valence(pGraph, pnNode);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}


int dglNodeGet_Valence( dglGraph_s * pGraph, dglInt32_t * pnNode )
{
#ifdef DGL_V2
	dglInt32_t * poutedgeset;
	dglInt32_t * pinedgeset;
	int c;
#endif

	pGraph->iErrno = 0;
	if ( pnNode) {
		switch( pGraph->Version ) {
#ifdef DGL_V2
		case 3:
				if ( DGL_NODE_STATUS_v2(pnNode) & DGL_NS_ALONE ) return 0;
				poutedgeset = dglNodeGet_OutEdgeset(pGraph, pnNode);
				pinedgeset = dglNodeGet_InEdgeset(pGraph, pnNode);
				c = 0;
				if ( poutedgeset ) c += DGL_EDGESET_EDGECOUNT_v2(poutedgeset);
				if ( pinedgeset ) c += DGL_EDGESET_EDGECOUNT_v2(pinedgeset);
				return c;
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}



dglInt32_t dglEdgesetGet_EdgeCount(dglGraph_s * pGraph, dglInt32_t * pnEdgeset)
{
	pGraph->iErrno = 0;
	if ( pnEdgeset ) {
		switch( pGraph->Version ) {
		case 1:
			return DGL_EDGESET_EDGECOUNT_v1(pnEdgeset);
#ifdef DGL_V2
		case 2:
		case 3:
			return DGL_EDGESET_EDGECOUNT_v2(pnEdgeset);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}

dglInt32_t dglEdgeGet_Cost( dglGraph_s * pGraph , dglInt32_t * pnEdge )
{
	pGraph->iErrno = 0;
	if (pnEdge) {
		switch(pGraph->Version) {
		case 1: return DGL_EDGE_COST_v1(pnEdge);
#ifdef DGL_V2
		case 2:
		case 3: return DGL_EDGE_COST_v2(pnEdge);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}

dglInt32_t dglEdgeGet_Id( dglGraph_s * pGraph , dglInt32_t * pnEdge )
{
	pGraph->iErrno = 0;
	if (pnEdge) {
		switch(pGraph->Version) {
		case 1: return DGL_EDGE_ID_v1(pnEdge);
#ifdef DGL_V2
		case 2:
		case 3: return DGL_EDGE_ID_v2(pnEdge);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return 0;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return 0;
}

dglInt32_t * dglEdgeGet_Head( dglGraph_s * pGraph , dglInt32_t * pnEdge )
{
	pGraph->iErrno = 0;
	if (pnEdge) {
		switch(pGraph->Version) {
		case 1:
			if ( pGraph->Flags & DGL_GS_FLAT ) {
				return DGL_NODEBUFFER_SHIFT_v1(pGraph,DGL_EDGE_HEADNODE_OFFSET_v1(pnEdge));
			}
			else {
				return dgl_get_node_V1(pGraph, DGL_EDGE_HEADNODE_OFFSET_v1(pnEdge));
			}
#ifdef DGL_V2
		case 2:
		case 3:
			if ( pGraph->Flags & DGL_GS_FLAT ) {
				return DGL_NODEBUFFER_SHIFT_v2(pGraph,DGL_EDGE_HEADNODE_OFFSET_v2(pnEdge));
			}
			else {
				return dgl_get_node_V2(pGraph, DGL_EDGE_HEADNODE_OFFSET_v2(pnEdge));
			}
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return NULL;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return NULL;
}

dglInt32_t * dglEdgeGet_Tail( dglGraph_s * pGraph , dglInt32_t * pnEdge )
{
	pGraph->iErrno = 0;
	if (pnEdge) {
		switch(pGraph->Version) {
		case 1:
			if ( pGraph->Flags & DGL_GS_FLAT ) {
				return DGL_NODEBUFFER_SHIFT_v1(pGraph,DGL_EDGE_TAILNODE_OFFSET_v1(pnEdge));
			}
			else {
				return dgl_get_node_V1(pGraph, DGL_EDGE_TAILNODE_OFFSET_v1(pnEdge));
			}
#ifdef DGL_V2
		case 2:
		case 3:
			if ( pGraph->Flags & DGL_GS_FLAT ) {
				return DGL_NODEBUFFER_SHIFT_v2(pGraph,DGL_EDGE_TAILNODE_OFFSET_v2(pnEdge));
			}
			else {
				return dgl_get_node_V2(pGraph, DGL_EDGE_TAILNODE_OFFSET_v2(pnEdge));
			}
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return NULL;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return NULL;
}

dglInt32_t * dglEdgeGet_Attr( dglGraph_s * pGraph , dglInt32_t * pnEdge )
{
	pGraph->iErrno = 0;
	if (pnEdge) {
		switch(pGraph->Version) {
		case 1: return DGL_EDGE_ATTR_PTR_v1(pnEdge);
#ifdef DGL_V2
		case 2:
		case 3: return DGL_EDGE_ATTR_PTR_v2(pnEdge);
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return NULL;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return NULL;
}

int dglEdgeSet_Attr( dglGraph_s * pGraph , dglInt32_t * pnAttr , dglInt32_t * pnEdge )
{
	if (pnEdge) {
		switch( pGraph->Version ) {
		case 1: memcpy(DGL_EDGE_ATTR_PTR_v1(pnEdge), pnAttr, pGraph->EdgeAttrSize);
				return 0;
#ifdef DGL_V2
		case 2:
		case 3: memcpy(DGL_EDGE_ATTR_PTR_v2(pnEdge), pnAttr, pGraph->EdgeAttrSize);
				return 0;
#endif
		}
		pGraph->iErrno = DGL_ERR_BadVersion;
		return -pGraph->iErrno;
	}
	pGraph->iErrno = DGL_ERR_UnexpectedNullPointer;
	return -pGraph->iErrno;
}



dglInt32_t * dglGetEdge(
				dglGraph_s * 	pGraph ,
				dglInt32_t 		nEdgeId
				)
{
	switch( pGraph->Version ) {
	case 1:
		return dgl_get_edge_V1(pGraph, nEdgeId );
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_get_edge_V2(pGraph, nEdgeId );
		break;
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}

int dglDelEdge(
				dglGraph_s * 	pGraph ,
				dglInt32_t 		nEdgeId
				)
{
	switch( pGraph->Version ) {
	case 1:
		return dgl_del_edge_V1(pGraph, nEdgeId );
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_del_edge_V2(pGraph, nEdgeId );
		break;
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}

int dglAddEdge(
				dglGraph_s * 	pGraph ,
				dglInt32_t 		nHead ,
				dglInt32_t 		nTail ,
				dglInt32_t 		nCost ,
				dglInt32_t 		nEdge
				)
{
	int 		nRet;
#ifdef DGL_STATS
	clock_t clk;
	clk = clock();
	pGraph->cAddEdge ++;
#endif
	switch( pGraph->Version ) {
	case 1:
		nRet = dgl_add_edge_V1(pGraph, nHead, nTail, nCost, nEdge, NULL, NULL, NULL, 0);
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_add_edge_V2(pGraph, nHead, nTail, nCost, nEdge, NULL, NULL, NULL, 0);
		break;
#endif
	default:
		pGraph->iErrno = DGL_ERR_BadVersion;
		nRet = -pGraph->iErrno;
		break;
	}
#ifdef DGL_STATS
	pGraph->clkAddEdge += clock() - clk;
#endif
	return nRet;
}

int dglAddEdgeX	(
				dglGraph_s * 	pGraph ,
				dglInt32_t 		nHead ,
				dglInt32_t 		nTail ,
				dglInt32_t 		nCost ,
				dglInt32_t 		nEdge ,
				void *			pvHeadAttr ,
				void *			pvTailAttr ,
				void *			pvEdgeAttr ,
				dglInt32_t		nFlags
				)
{
	int 		nRet;
#ifdef DGL_STATS
	clock_t clk;
	clk = clock();
	pGraph->cAddEdge ++;
#endif
	switch( pGraph->Version ) {
	case 1:
		nRet = dgl_add_edge_V1(pGraph, nHead, nTail, nCost, nEdge, pvHeadAttr, pvTailAttr, pvEdgeAttr, nFlags);
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_add_edge_V2(pGraph, nHead, nTail, nCost, nEdge, pvHeadAttr, pvTailAttr, pvEdgeAttr, nFlags);
		break;
#endif
	default:
		pGraph->iErrno = DGL_ERR_BadVersion;
		nRet = -pGraph->iErrno;
		break;
	}
#ifdef DGL_STATS
	pGraph->clkAddEdge += clock() - clk;
#endif
	return nRet;
}

int dglAddNode(
				dglGraph_s * 	pGraph ,
				dglInt32_t 		nNodeId ,
				void *			pvNodeAttr ,
				dglInt32_t		nFlags
				)
{
	int 		nRet;
	switch( pGraph->Version ) {
	case 1:
		nRet = dgl_add_node_V1(pGraph, nNodeId, pvNodeAttr, nFlags);
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_add_node_V2(pGraph, nNodeId, pvNodeAttr, nFlags);
		break;
#endif
	default:
		pGraph->iErrno = DGL_ERR_BadVersion;
		nRet = -pGraph->iErrno;
		break;
	}
	return nRet;
}

int dglDelNode(
				dglGraph_s * 	pGraph ,
				dglInt32_t 		nNodeId
				)
{
	int 		nRet;
	switch( pGraph->Version ) {
	case 1:
		nRet = dgl_del_node_V1(pGraph, nNodeId);
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_del_node_V2(pGraph, nNodeId);
		break;
#endif
	default:
		pGraph->iErrno = DGL_ERR_BadVersion;
		nRet = -pGraph->iErrno;
		break;
	}
	return nRet;
}

int dglWrite( dglGraph_s * pGraph, int fd )
{
	int nRet;

	switch( pGraph->Version ) {
	case 1:
		nRet = dgl_write_V1(pGraph, fd);
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_write_V2(pGraph, fd);
		break;
#endif
	default:
		pGraph->iErrno = DGL_ERR_BadVersion;
		nRet = -pGraph->iErrno;
		break;
	}
	return nRet;
}

int dglRead( dglGraph_s * pGraph, int fd )
{
	dglByte_t bVersion;
	int	nRet;

	if ( read( fd , & bVersion , 1 ) != 1 ) {
		pGraph->iErrno = DGL_ERR_Read;
		nRet = -pGraph->iErrno;
	}
	else {
		switch( bVersion ) {
		case 1:
			nRet = dgl_read_V1( pGraph, fd );
			break;
#ifdef DGL_V2
		case 2:
		case 3:
			nRet = dgl_read_V2( pGraph, fd, bVersion );
			break;
#endif
		default:
			pGraph->iErrno = DGL_ERR_VersionNotSupported;
			nRet = -pGraph->iErrno;
			break;
		}
	}
	return nRet;
}


int dglShortestPath	(
					 	dglGraph_s * 	 pGraph,
						dglSPReport_s **ppReport,
					 	dglInt32_t 		 nStart,
					 	dglInt32_t 		 nDestination,
						dglSPClip_fn	 fnClip,
						void *			 pvClipArg,
						dglSPCache_s * pCache
					 	)
{
	int nRet;

	switch( pGraph->Version ) {
	case 1:
		nRet = dgl_dijkstra_V1( pGraph, ppReport, NULL, nStart, nDestination, fnClip, pvClipArg, pCache );
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_dijkstra_V2( pGraph, ppReport, NULL, nStart, nDestination, fnClip, pvClipArg, pCache );
		break;
#endif
	default:
		pGraph->iErrno = DGL_ERR_BadVersion;
		nRet = -pGraph->iErrno;
		break;
	}
	return nRet;
}


int dglShortestDistance	(
					 		dglGraph_s * 	 pGraph,
							dglInt32_t *      pnDistance ,
					 		dglInt32_t 		 nStart,
					 		dglInt32_t 		 nDestination,
							dglSPClip_fn	 fnClip,
							void *			 pvClipArg,
							dglSPCache_s * pCache
					 		)
{
	int nRet;

	switch( pGraph->Version ) {
	case 1:
		nRet = dgl_dijkstra_V1( pGraph, NULL, pnDistance, nStart, nDestination, fnClip, pvClipArg, pCache );
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_dijkstra_V2( pGraph, NULL, pnDistance, nStart, nDestination, fnClip, pvClipArg, pCache );
		break;
#endif
	default:
		pGraph->iErrno = DGL_ERR_BadVersion;
		nRet = -pGraph->iErrno;
		break;
	}
	return nRet;
}


int	dglDepthSpanning	(
						dglGraph_s *  	pgraphInput,
						dglGraph_s *  	pgraphOutput,
						dglInt32_t			nVertexNode,
						dglSpanClip_fn	fnClip,
						void *				pvClipArg
						)
{
	int nRet;
	void * pvVisited;

	if ( dglGet_EdgeCount(pgraphInput) == 0 ) { /* no span */
		pgraphInput->iErrno = 0;
		return 0;
	}

#ifndef DGL_V2
	if ( pgraphInput->Version == 2 ) {
		pgraphInput->iErrno = DGL_ERR_BadVersion;
		return -pgraphInput->iErrno;
	}
#endif

	nRet = dglInitialize( pgraphOutput,
			dglGet_Version(pgraphInput),
			dglGet_NodeAttrSize(pgraphInput),
			dglGet_EdgeAttrSize(pgraphInput), 
			dglGet_Opaque(pgraphInput) );

	if ( nRet < 0 ) return nRet;

	if ( (pvVisited = avl_create( dglTreeNodeCompare, NULL, dglTreeGetAllocator() )) == NULL ) {
		pgraphInput->iErrno = DGL_ERR_MemoryExhausted;
		return -pgraphInput->iErrno;
	}

	switch( pgraphInput->Version ) {
	case 1:
		nRet = dgl_depthfirst_spanning_V1( pgraphInput, pgraphOutput, nVertexNode , pvVisited , fnClip , pvClipArg );
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_depthfirst_spanning_V2( pgraphInput, pgraphOutput, nVertexNode , pvVisited , fnClip , pvClipArg );
		break;
#endif
	default:
		pgraphInput->iErrno = DGL_ERR_BadVersion;
		nRet = -pgraphInput->iErrno;
		break;
	}

	avl_destroy( pvVisited, dglTreeNodeCancel );

	if ( nRet < 0 ) {
		dglRelease( pgraphOutput );
	}

	return nRet;
}

int dglDepthComponents(
						dglGraph_s *  	pgraphInput,
						dglGraph_s *  	pgraphComponents,
						int					cgraphComponents,
						dglSpanClip_fn	fnClip,
						void *				pvClipArg
						)
{
	int i, nret = 0;
	dglTreeNode_s findVisited;
	void * pvVisited;
	dglInt32_t * pvertex , * pnode;

	if ( dglGet_EdgeCount(pgraphInput) == 0 ) { /* no span */
		pgraphInput->iErrno = 0;
		return 0;
	}

#ifndef DGL_V2
	if ( pgraphInput->Version == 2 || pgraphInput->Version == 3 ) {
		pgraphInput->iErrno = DGL_ERR_BadVersion;
		return -pgraphInput->iErrno;
	}
#endif

	if ( (pvVisited = avl_create( dglTreeNodeCompare, NULL, dglTreeGetAllocator() )) == NULL ) {
		pgraphInput->iErrno = DGL_ERR_MemoryExhausted; goto error;
	}

	/*
	 * choose a vertex to start from
	 */
	pvertex = NULL;
	{
		dglNodeTraverser_s pT;

		dglNode_T_Initialize( &pT, pgraphInput );
		for( pnode = dglNode_T_First( &pT ); pnode; pnode = dglNode_T_Next( &pT ) ) {
			switch(pgraphInput->Version) {
			case 1: if ( DGL_NODE_STATUS_v1(pnode) & DGL_NS_HEAD ) pvertex = pnode; break;
#ifdef DGL_V2
			case 2:
			case 3: if ( DGL_NODE_STATUS_v2(pnode) & DGL_NS_HEAD ) pvertex = pnode; break;
#endif
			}
			if ( pvertex ) break;
		}
		dglNode_T_Release( &pT );
	}

	if ( pvertex == NULL ) {
		pgraphInput->iErrno = DGL_ERR_UnexpectedNullPointer; goto error;
	}

	for (
		i = 0;
		i < cgraphComponents && pvertex;
		i++
		)
	{
		nret = dglInitialize( & pgraphComponents[i],
				dglGet_Version(pgraphInput),
				dglGet_NodeAttrSize(pgraphInput),
				dglGet_EdgeAttrSize(pgraphInput), 
				dglGet_Opaque(pgraphInput) );

		if ( nret < 0 ) goto error;

		switch( pgraphInput->Version ) {
		case 1:
			nret = dgl_depthfirst_spanning_V1(pgraphInput, & pgraphComponents[i], DGL_NODE_ID_v1(pvertex), pvVisited, fnClip, pvClipArg);
			if ( nret < 0 ) goto error;
			break;
#ifdef DGL_V2
		case 2:
		case 3:
			nret = dgl_depthfirst_spanning_V2(pgraphInput, & pgraphComponents[i], DGL_NODE_ID_v1(pvertex), pvVisited, fnClip, pvClipArg);
			if ( nret < 0 ) goto error;
			break;
#endif
		default:
			pgraphInput->iErrno = DGL_ERR_BadVersion;
			nret = -pgraphInput->iErrno;
			goto error;
		}
		
		/*
		 * select next unvisited vertex
		 */
		pvertex = NULL;
		{
			dglNodeTraverser_s pT;

			dglNode_T_Initialize( &pT, pgraphInput );
			for( pnode = dglNode_T_First(  &pT ); pnode; pnode = dglNode_T_Next( &pT ) ) {
				switch(pgraphInput->Version) {
				case 1: if ( DGL_NODE_STATUS_v1(pnode) & DGL_NS_HEAD ) {
							findVisited.nKey = DGL_NODE_ID_v1(pnode);
							if ( avl_find( pvVisited, &findVisited ) == NULL ) {
								pvertex = pnode;
								break;
							}
						}
						break;
#ifdef DGL_V2
				case 2:
				case 3: if ( DGL_NODE_STATUS_v2(pnode) & DGL_NS_HEAD ) {
							findVisited.nKey = DGL_NODE_ID_v2(pnode);
							if ( avl_find( pvVisited, &findVisited ) == NULL ) {
								pvertex = pnode;
								break;
							}
						}
						break;
#endif
				}
				if ( pvertex ) break;
			}
			dglNode_T_Release( &pT );
		}
	}

	avl_destroy( pvVisited, dglTreeNodeCancel );
	return i;

error:
	avl_destroy( pvVisited, dglTreeNodeCancel );
	return nret;
}

int	dglMinimumSpanning(
						dglGraph_s *  	pgraphInput,
						dglGraph_s *  	pgraphOutput,
						dglInt32_t			nVertexNode,
						dglSpanClip_fn	fnClip,
						void *				pvClipArg
						)
{
	int nRet;

	if ( dglGet_EdgeCount(pgraphInput) == 0 ) { /* no span */
		pgraphInput->iErrno = 0;
		return 0;
	}

	nRet = dglInitialize( pgraphOutput,
			dglGet_Version(pgraphInput),
			dglGet_NodeAttrSize(pgraphInput),
			dglGet_EdgeAttrSize(pgraphInput), 
			dglGet_Opaque(pgraphInput) );

	if ( nRet < 0 ) return nRet;

	switch( pgraphInput->Version ) {
	case 1:
		nRet = dgl_minimum_spanning_V1( pgraphInput, pgraphOutput, nVertexNode , fnClip , pvClipArg );
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		nRet = dgl_minimum_spanning_V2( pgraphInput, pgraphOutput, nVertexNode , fnClip , pvClipArg );
		break;
#endif
	default:
		pgraphInput->iErrno = DGL_ERR_BadVersion;
		nRet = -pgraphInput->iErrno;
		break;
	}
	if ( nRet < 0 ) {
		dglRelease( pgraphOutput );
	}
	return nRet;
}

void dglFreeSPReport( dglGraph_s * pgraph , dglSPReport_s * pSPReport )
{
	int iArc;
	if ( pSPReport )
	{
		if ( pSPReport->pArc )
		{
			for ( iArc = 0 ; iArc < pSPReport->cArc ; iArc ++ ) {
				if ( pSPReport->pArc[iArc].pnEdge ) free( pSPReport->pArc[iArc].pnEdge );
			}
			free( pSPReport->pArc );
		}
		free( pSPReport );
	}
}

int dglInitializeSPCache( dglGraph_s * pGraph, dglSPCache_s * pCache ) {
	switch( pGraph->Version ) {
	case 1:
		return dgl_sp_cache_initialize_V1( pGraph, pCache, 0 );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_sp_cache_initialize_V2( pGraph, pCache, 0 );
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}

void dglReleaseSPCache( dglGraph_s * pGraph, dglSPCache_s * pCache ) {
	pGraph->iErrno = 0;
	switch( pGraph->Version ) {
	case 1:
		dgl_sp_cache_release_V1( pGraph, pCache );
		break;
#ifdef DGL_V2
	case 2:
	case 3:
		dgl_sp_cache_release_V2( pGraph, pCache );
		break;
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
}


int dglErrno( dglGraph_s * pgraph )
{
	return pgraph->iErrno;
}

char * dglStrerror( dglGraph_s * pgraph )
{
	switch( pgraph->iErrno )
	{
	case DGL_ERR_BadVersion:
		return "Bad Version";
	case DGL_ERR_BadNodeType:
		return "Bad Node Type";
	case DGL_ERR_MemoryExhausted:
		return "Memory Exhausted";
	case DGL_ERR_HeapError:
		return "Heap Error";
	case DGL_ERR_UndefinedMethod:
		return "Undefined Method";
	case DGL_ERR_Write:
		return "Write";
	case DGL_ERR_Read:
		return "Read";
	case DGL_ERR_NotSupported:
		return "Not Supported";
	case DGL_ERR_UnknownByteOrder:
		return "Unknown Byte Order";
	case DGL_ERR_NodeNotFound:
		return "Node Not Found";
	case DGL_ERR_HeadNodeNotFound:
		return "Head Node Not Found";
	case DGL_ERR_TailNodeNotFound:
		return "Tail Node Not Found";
	case DGL_ERR_BadEdge:
		return "Bad Edge";
	case DGL_ERR_BadOnFlatGraph:
		return "Operation Not Supported On Flat-State Graph";
	case DGL_ERR_BadOnTreeGraph:
		return "Operation Not Supported On Tree-State Graph";
	case DGL_ERR_TreeSearchError:
		return "Tree Search Error";
	case DGL_ERR_UnexpectedNullPointer:
		return "Unexpected Null Pointer";
	case DGL_ERR_VersionNotSupported:
		return "Version Not Supported";
	case DGL_ERR_EdgeNotFound:
		return "Edge Not Found";
	case DGL_ERR_NodeAlreadyExist:
		return "Node Already Exist";
	case DGL_ERR_NodeIsAComponent:
		return "Node Is A Component";
	case DGL_ERR_EdgeAlreadyExist:
		return "Edge Already Exist";
	case DGL_ERR_BadArgument:
		return "Bad Argument";
	}

	return "unknown graph error code";
}

/*
 * dglGraph_s hiders
 */
int	dglGet_Version		(dglGraph_s *  pgraph) {
	return pgraph->Version;
}
void dglSet_Version		(dglGraph_s *  pgraph, int nVersion) {
	pgraph->Version = nVersion;
}
int	dglGet_Endianess		(dglGraph_s *  pgraph) {
	return pgraph->Endian;
}
int	dglGet_NodeAttrSize	(dglGraph_s *  pgraph) {
	return pgraph->NodeAttrSize;
}
int	dglGet_EdgeAttrSize	(dglGraph_s *  pgraph) {
	return pgraph->EdgeAttrSize;
}
int	dglGet_NodeCount		(dglGraph_s *  pgraph) {
	return pgraph->cNode;
}
int	dglGet_HeadNodeCount	(dglGraph_s *  pgraph) {
	return pgraph->cHead;
}
int	dglGet_TailNodeCount	(dglGraph_s *  pgraph) {
	return pgraph->cTail;
}
int	dglGet_AloneNodeCount	(dglGraph_s *  pgraph) {
	return pgraph->cAlone;
}
int	dglGet_EdgeCount		(dglGraph_s *  pgraph) {
	return pgraph->cEdge;
}
int	dglGet_State		(dglGraph_s *  pgraph) {
	return pgraph->Flags;
}
dglInt32_t * dglGet_Opaque	(dglGraph_s *  pgraph) {
	return pgraph->aOpaqueSet;
}
void dglSet_Opaque( dglGraph_s * pgraph, dglInt32_t * pOpaque ) {
	memcpy( pgraph->aOpaqueSet , pOpaque , sizeof( dglInt32_t ) * 16 );
}
int dglGet_NodeSize		(dglGraph_s *  pgraph) {
	switch(pgraph->Version) {
	case 1:
		return DGL_NODE_SIZEOF_v1( pgraph->NodeAttrSize );
#ifdef DGL_V2
	case 2:
	case 3:
		return DGL_NODE_SIZEOF_v2( pgraph->NodeAttrSize );
#endif
	}
	pgraph->iErrno = DGL_ERR_BadVersion;
	return -pgraph->iErrno;
}
int dglGet_EdgeSize		(dglGraph_s *  pgraph) {
	switch(pgraph->Version) {
	case 1:
		return DGL_EDGE_SIZEOF_v1( pgraph->NodeAttrSize );
#ifdef DGL_V2
	case 2:
	case 3:
		return DGL_EDGE_SIZEOF_v2( pgraph->NodeAttrSize );
#endif
	}
	pgraph->iErrno = DGL_ERR_BadVersion;
	return -pgraph->iErrno;
}
dglInt64_t dglGet_Cost(dglGraph_s *  pgraph) {
	return pgraph->nnCost;
}
void dglSet_Cost(dglGraph_s * pgraph, dglInt64_t nnCost) {
	pgraph->nnCost = nnCost;
}
dglInt32_t dglGet_Family(dglGraph_s * pgraph) {
	return pgraph->nFamily;
}
void dglSet_Family(dglGraph_s * pgraph, dglInt32_t nFamily) {
	pgraph->nFamily = nFamily;
}
dglInt32_t dglGet_Options(dglGraph_s * pgraph) {
	return pgraph->nOptions;
}
void dglSet_Options(dglGraph_s * pgraph, dglInt32_t nOptions) {
	pgraph->nOptions = nOptions;
}
dglEdgePrioritizer_s * dglGet_EdgePrioritizer(dglGraph_s * pGraph) {
	return & pGraph->edgePrioritizer;
}
dglNodePrioritizer_s * dglGet_NodePrioritizer(dglGraph_s * pGraph) {
	return & pGraph->nodePrioritizer;
}



/*
 * Node Traverse
 */
int dglNode_T_Initialize( dglNodeTraverser_s * pT , dglGraph_s * pGraph ) {
	switch( pGraph->Version ) {
	case 1:
		return dgl_node_t_initialize_V1( pGraph, pT );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_node_t_initialize_V2( pGraph, pT );
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}

void dglNode_T_Release( dglNodeTraverser_s * pT ) {
	switch( pT->pGraph->Version ) {
	case 1:
		dgl_node_t_release_V1( pT );
		return;
#ifdef DGL_V2
	case 2:
	case 3:
		dgl_node_t_release_V2( pT );
		return;
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
}

dglInt32_t * dglNode_T_First( dglNodeTraverser_s * pT ) {
	switch( pT->pGraph->Version ) {
	case 1:
		return dgl_node_t_first_V1( pT );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_node_t_first_V2( pT );
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}

dglInt32_t * dglNode_T_Next( dglNodeTraverser_s * pT ) {
	switch( pT->pGraph->Version ) {
	case 1:
		return dgl_node_t_next_V1( pT );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_node_t_next_V2( pT );
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}

dglInt32_t * dglNode_T_Find( dglNodeTraverser_s * pT , dglInt32_t nNodeId ) {
	switch( pT->pGraph->Version ) {
	case 1:
		return dgl_node_t_find_V1( pT , nNodeId );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_node_t_find_V2( pT , nNodeId );
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}

/*
 * Edge Traverser
 */
int	dglEdge_T_Initialize(
			dglEdgeTraverser_s * pT ,
			dglGraph_s * pGraph ,
			dglEdgePrioritizer_s * pEdgePrioritizer
			)
{
	switch( pGraph->Version ) {
	case 1:
		return dgl_edge_t_initialize_V1( pGraph, pT , pEdgePrioritizer );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_edge_t_initialize_V2( pGraph, pT , pEdgePrioritizer );
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}
void dglEdge_T_Release( dglEdgeTraverser_s * pT )
{
	switch( pT->pGraph->Version ) {
	case 1:
		dgl_edge_t_release_V1( pT );
		return;
#ifdef DGL_V2
	case 2:
	case 3:
		dgl_edge_t_release_V2( pT );
		return;
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
}
dglInt32_t *	dglEdge_T_First( dglEdgeTraverser_s * pT )
{
	switch( pT->pGraph->Version ) {
	case 1:
		return dgl_edge_t_first_V1( pT );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_edge_t_first_V2( pT );
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}
dglInt32_t *	dglEdge_T_Next( dglEdgeTraverser_s * pT )
{
	switch( pT->pGraph->Version ) {
	case 1:
		return dgl_edge_t_next_V1( pT );
#ifdef DGL_V2
	case 2:
	case 3:
		return dgl_edge_t_next_V2( pT );
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}


int	dglEdgeset_T_Initialize	(
			dglEdgesetTraverser_s * pT ,
			dglGraph_s * pGraph ,
			dglInt32_t * pnEdgeset
			)
{
	switch(pGraph->Version) {
	case 1: return dgl_edgeset_t_initialize_V1(pGraph,pT,pnEdgeset);
#ifdef DGL_V2
	case 2:
	case 3: return dgl_edgeset_t_initialize_V2(pGraph,pT,pnEdgeset);
#endif
	}
	pGraph->iErrno = DGL_ERR_BadVersion;
	return -pGraph->iErrno;
}

void dglEdgeset_T_Release( dglEdgesetTraverser_s * pT )
{
}

dglInt32_t *	dglEdgeset_T_First( dglEdgesetTraverser_s * pT )
{
	switch(pT->pGraph->Version) {
	case 1: return dgl_edgeset_t_first_V1(pT);
#ifdef DGL_V2
	case 2:
	case 3: return dgl_edgeset_t_first_V2(pT);
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}

dglInt32_t *	dglEdgeset_T_Next( dglEdgesetTraverser_s * pT )
{
	switch(pT->pGraph->Version) {
	case 1: return dgl_edgeset_t_next_V1(pT);
#ifdef DGL_V2
	case 2:
	case 3: return dgl_edgeset_t_next_V2(pT);
#endif
	}
	pT->pGraph->iErrno = DGL_ERR_BadVersion;
	return NULL;
}


/*
 * chunked I/O
 */

#define __CIO_BEGIN	0
#define __CIO_W_HEADER 1
#define __CIO_W_NODEBUFFER 2
#define __CIO_W_EDGEBUFFER 3
#define __CIO_R_HEADER 4
#define __CIO_R_NODEBUFFER 5
#define __CIO_R_EDGEBUFFER 6
#define __CIO_END 7

int dglIOContextInitialize(dglGraph_s * pG, dglIOContext_s * pIO) {
	pIO->pG = pG;
	pIO->nState = __CIO_BEGIN;
	pIO->cb = 0;
	pIO->ib = 0;
	pIO->pb = NULL;
	return 0;
}

void dglIOContextRelease( dglIOContext_s * pIO ) {
}

int dglWriteChunk(dglIOContext_s * pIO, dglWriteChunk_fn pfn, void * pv)
{
	unsigned char * pb;
	int cb;

	switch( pIO->nState ) {
	case __CIO_BEGIN:
		pIO->pb = pIO->ab;
		pb = pIO->pb;
		memcpy( pb,   & pIO->pG->Version        , 1    ); pb += 1;  /* 1 */
		memcpy( pb,   & pIO->pG->Endian         , 1    ); pb += 1;  /* 2 */
		memcpy( pb,   & pIO->pG->NodeAttrSize   , 4    ); pb += 4;  /* 6 */
		memcpy( pb,   & pIO->pG->EdgeAttrSize   , 4    ); pb += 4;  /* 10 */
		memcpy( pb,   & pIO->pG->aOpaqueSet     , 64   ); pb += 64; /* 74 */
		memcpy( pb,   & pIO->pG->nOptions       , 4    ); pb += 4;  /* 78 */
		memcpy( pb,   & pIO->pG->nFamily        , 4    ); pb += 4;  /* 82 */
		memcpy( pb,   & pIO->pG->nnCost         , 8    ); pb += 8;  /* 90 */
		memcpy( pb,   & pIO->pG->cNode          , 4    ); pb += 4;  /* 94 */
		memcpy( pb,   & pIO->pG->cHead          , 4    ); pb += 4;  /* 98 */
		memcpy( pb,   & pIO->pG->cTail          , 4    ); pb += 4;  /* 102 */
		memcpy( pb,   & pIO->pG->cAlone         , 4    ); pb += 4;  /* 106 */
		memcpy( pb,   & pIO->pG->cEdge          , 4    ); pb += 4;  /* 110 */
		memcpy( pb,   & pIO->pG->iNodeBuffer    , 4    ); pb += 4;  /* 114 */
		memcpy( pb,   & pIO->pG->iEdgeBuffer    , 4    ); pb += 4;  /* 118 */
		pIO->cb = 118;
		cb = pfn(pIO->pG, pIO->pb, pIO->cb, pv);
		if (cb >= 0) {
			pIO->ib += cb;
			if ((pIO->cb - pIO->ib) == 0) {
				pIO->ib = 0;
				pIO->cb = pIO->pG->iNodeBuffer;
				pIO->pb = pIO->pG->pNodeBuffer;
				pIO->nState = __CIO_W_NODEBUFFER;
			}
			else {
				pIO->nState = __CIO_W_HEADER;
			}
		}
		return cb;
	case __CIO_W_HEADER:
		cb = pfn(pIO->pG, pIO->pb + pIO->ib, pIO->cb - pIO->ib, pv);
		if (cb > 0) {
			pIO->ib += cb;
			if ((pIO->cb - pIO->ib) == 0) {
				if ( pIO->pG->iNodeBuffer > 0 ) {
					pIO->ib = 0;
					pIO->cb = pIO->pG->iNodeBuffer;
					pIO->pb = pIO->pG->pNodeBuffer;
					pIO->nState = __CIO_W_NODEBUFFER;
				}
				else if ( pIO->pG->iEdgeBuffer > 0 ) {
					pIO->ib = 0;
					pIO->cb = pIO->pG->iEdgeBuffer;
					pIO->pb = pIO->pG->pEdgeBuffer;
					pIO->nState = __CIO_W_EDGEBUFFER;
				}
				else {
					pIO->nState = __CIO_END;
				}
			}
			else {
				pIO->nState = __CIO_W_HEADER;
			}
		}
		return cb;
	case __CIO_W_NODEBUFFER:
		cb = pfn(pIO->pG, pIO->pb + pIO->ib, pIO->cb - pIO->ib, pv);
		if (cb > 0) {
			pIO->ib += cb;
			if ((pIO->cb - pIO->ib) == 0) {
				if ( pIO->pG->iEdgeBuffer > 0 ) {
					pIO->ib = 0;
					pIO->cb = pIO->pG->iEdgeBuffer;
					pIO->pb = pIO->pG->pEdgeBuffer;
					pIO->nState = __CIO_W_EDGEBUFFER;
				}
				else {
					pIO->nState = __CIO_END;
				}
			}
		}
		return cb;
	case __CIO_W_EDGEBUFFER:
		cb = pfn(pIO->pG, pIO->pb + pIO->ib, pIO->cb - pIO->ib, pv);
		if (cb > 0) {
			pIO->ib += cb;
			if ((pIO->cb - pIO->ib) == 0) {
				pIO->nState = __CIO_END;
			}
		}
		return cb;
	case __CIO_END:
		pfn(pIO->pG, NULL, 0, pv); /* notify end of graph */
		return 0;
	}
	return 0;
}

#ifndef MIN
#define MIN(x,y)	(((x)<(y))?x:y)
#endif

int dglReadChunk(dglIOContext_s * pIO, dglByte_t * pbChunk, int cbChunk)
{
	int i, c;
	unsigned char * pb;

	switch( pIO->nState ) {
	case __CIO_BEGIN:
		pIO->cb = 118;
		pIO->ib = 0;
		pIO->pb = pIO->ab;

		c = MIN(cbChunk, 118);
		memcpy( pIO->pb, pbChunk, c );
		pIO->ib += c;
		if ((pIO->cb - pIO->ib) == 0)
			goto init_nodebuffer;
		pIO->nState = __CIO_R_HEADER;
		return c;

	case __CIO_R_HEADER:
		c = MIN(cbChunk , pIO->cb - pIO->ib);
		memcpy( pIO->pb + pIO->ib, pbChunk, c );
		pIO->ib += c;
		init_nodebuffer:
		if ((pIO->cb - pIO->ib) == 0) {
			pb = pIO->pb;
			memcpy( & pIO->pG->Version      , pb , 1  ); pb += 1;  /* 1 */
			memcpy( & pIO->pG->Endian       , pb , 1  ); pb += 1;  /* 2 */
			memcpy( & pIO->pG->NodeAttrSize , pb , 4  ); pb += 4;  /* 6 */
			memcpy( & pIO->pG->EdgeAttrSize , pb , 4  ); pb += 4;  /* 10 */
			memcpy( & pIO->pG->aOpaqueSet   , pb , 64 ); pb += 64; /* 74 */
			memcpy( & pIO->pG->nOptions     , pb , 4  ); pb += 4;  /* 78 */
			memcpy( & pIO->pG->nFamily      , pb , 4  ); pb += 4;  /* 82 */
			memcpy( & pIO->pG->nnCost       , pb , 8  ); pb += 8;  /* 90 */
			memcpy( & pIO->pG->cNode        , pb , 4  ); pb += 4;  /* 94 */
			memcpy( & pIO->pG->cHead        , pb , 4  ); pb += 4;  /* 98 */
			memcpy( & pIO->pG->cTail        , pb , 4  ); pb += 4;  /* 102 */
			memcpy( & pIO->pG->cAlone       , pb , 4  ); pb += 4;  /* 106 */
			memcpy( & pIO->pG->cEdge        , pb , 4  ); pb += 4;  /* 110 */
			memcpy( & pIO->pG->iNodeBuffer  , pb , 4  ); pb += 4;  /* 114 */
			memcpy( & pIO->pG->iEdgeBuffer  , pb , 4  ); pb += 4;  /* 118 */

			pIO->fSwap = 0;
#ifdef DGL_ENDIAN_BIG
			if ( pIO->pG->Endian == DGL_ENDIAN_LITTLE ) pIO->fSwap = 1;
#else
			if ( pIO->pG->Endian == DGL_ENDIAN_BIG    ) pIO->fSwap = 1;
#endif
			if ( pIO->fSwap ) {
				dgl_swapInt32Bytes( & pIO->pG->NodeAttrSize );
				dgl_swapInt32Bytes( & pIO->pG->EdgeAttrSize );
				dgl_swapInt32Bytes( & pIO->pG->nOptions );
				dgl_swapInt32Bytes( & pIO->pG->nFamily );
				dgl_swapInt64Bytes( & pIO->pG->nnCost );
				dgl_swapInt32Bytes( & pIO->pG->cNode );
				dgl_swapInt32Bytes( & pIO->pG->cHead );
				dgl_swapInt32Bytes( & pIO->pG->cTail );
				dgl_swapInt32Bytes( & pIO->pG->cAlone );
				dgl_swapInt32Bytes( & pIO->pG->cEdge );
				dgl_swapInt32Bytes( & pIO->pG->iNodeBuffer );
				dgl_swapInt32Bytes( & pIO->pG->iEdgeBuffer );

				for ( i = 0 ; i < 16 ; i ++ ) {
					dgl_swapInt32Bytes( & pIO->pG->aOpaqueSet[i] );
				}

#ifdef DGL_ENDIAN_BIG
				pIO->pG->Endian = DGL_ENDIAN_BIG;
#else
				pIO->pG->Endian = DGL_ENDIAN_LITTLE;
#endif
			}

			if ( pIO->pG->iNodeBuffer > 0 ) {
				pIO->pG->pNodeBuffer = malloc( pIO->pG->iNodeBuffer );
				if ( pIO->pG->pNodeBuffer == NULL ) {
					return -1;
				}
				pIO->cb = pIO->pG->iNodeBuffer;
				pIO->pb = pIO->pG->pNodeBuffer;
				pIO->ib = 0;
				pIO->nState = __CIO_R_NODEBUFFER;
			}
			else {
				goto init_edgebuffer;
			}
		}
		return c;
	case __CIO_R_NODEBUFFER:
		c = MIN(cbChunk , pIO->cb - pIO->ib);
		memcpy( pIO->pb + pIO->ib, pbChunk, c );
		pIO->ib += c;
		init_edgebuffer:
		if ((pIO->cb - pIO->ib) == 0) {
			if ( pIO->pG->iEdgeBuffer > 0 ) {
				pIO->pG->pEdgeBuffer = malloc( pIO->pG->iEdgeBuffer );
				if ( pIO->pG->pEdgeBuffer == NULL ) {
					return -1;
				}
				pIO->cb = pIO->pG->iEdgeBuffer;
				pIO->pb = pIO->pG->pEdgeBuffer;
				pIO->ib = 0;
				pIO->nState = __CIO_R_EDGEBUFFER;
			}
			else {
				pIO->nState = __CIO_END;
			}
		}
		return c;
	case __CIO_R_EDGEBUFFER:
		c = MIN(cbChunk , pIO->cb - pIO->ib);
		memcpy( pIO->pb + pIO->ib, pbChunk, c );
		pIO->ib += c;
		if ((pIO->cb - pIO->ib) == 0) {
			pIO->nState = __CIO_END;
		}
		return c;
	case __CIO_END:
		{
			/* switch on FLAT bit */
			pIO->pG->Flags |= DGL_GS_FLAT;

			/* nodebuffer and edgebuffer are both arrays on 32 bit integer
			 * byte order swapping is straightforward
			 */
			if (pIO->fSwap && pIO->pG->iNodeBuffer > 0) {
				int in, cn;
				dglInt32_t * pn;
				for (
						cn = pIO->pG->iNodeBuffer / sizeof(dglInt32_t),
						pn = (dglInt32_t*)pIO->pG->pNodeBuffer,
						in = 0 ;
						in < cn ;
						in ++
					)
				{
					dgl_swapInt32Bytes( & pn[in] );
				}
			}
			if (pIO->fSwap && pIO->pG->iEdgeBuffer > 0) {
				int in, cn;
				dglInt32_t * pn;
				for (
						cn = pIO->pG->iEdgeBuffer / sizeof(dglInt32_t),
						pn = (dglInt32_t*)pIO->pG->pEdgeBuffer,
						in = 0 ;
						in < cn ;
						in ++
					)
				{
					dgl_swapInt32Bytes( & pn[in] );
				}
			}
		}
		return 0;
	default:
		return 0;
	}
}