/*
 * YAFFS: Yet another FFS. A NAND-flash specific file system. 
 *
 * yaffs_packedtags2.c: Tags packing for YAFFS2
 *
 * Copyright (C) 2002 Aleph One Ltd.
 *
 * Created by Charles Manning <charles@aleph1.co.uk>
 *
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * version 2.1 as published by the Free Software Foundation.
 */
 
#include "yaffs_packedtags2.h"
#include "yportenv.h"
#include "yaffs_tagsvalidity.h"



// This code packs a set of extended tags into a binary structure for NAND storage

// Some of the information is "extra" struff which can be packed in to speed scanning
// This is defined by having the EXTRA_HEADER_INFO_FLAG set.


// Extra flags applied to chunkId

#define EXTRA_HEADER_INFO_FLAG	0x80000000
#define EXTRA_SHRINK_FLAG	0x40000000
#define EXTRA_SPARE_FLAGS	0x30000000

#define ALL_EXTRA_FLAGS		0xF0000000



// Also, the top 4 bits of the object Id are set to the object type.
#define EXTRA_OBJECT_TYPE_SHIFT (28)
#define EXTRA_OBJECT_TYPE_MASK  ((0x0F) << EXTRA_OBJECT_TYPE_SHIFT)



static void yaffs_DumpPackedTags2(const yaffs_PackedTags2 *pt)
{
	T(YAFFS_TRACE_MTD,(TSTR("packed tags obj %d chunk %d byte %d seq %d\n"),pt->t.objectId,pt->t.chunkId,pt->t.byteCount,pt->t.sequenceNumber));
}

static void yaffs_DumpTags2(const yaffs_ExtendedTags *t)
{
	T(YAFFS_TRACE_MTD,(TSTR("ext.tags eccres %d blkbad %d chused %d obj %d chunk%d byte %d del %d ser %d seq %d\n"),
	     t->eccResult, t->blockBad, t->chunkUsed, t->objectId, t->chunkId, t->byteCount, t->chunkDeleted, t->serialNumber, t->sequenceNumber));
	  
}

void yaffs_PackTags2(yaffs_PackedTags2 *pt, const yaffs_ExtendedTags *t)
{
	pt->t.chunkId = t->chunkId;
	pt->t.sequenceNumber = t->sequenceNumber;
	pt->t.byteCount = t->byteCount;
	pt->t.objectId = t->objectId;
	
	if(t->chunkId == 0 && t->extraHeaderInfoAvailable)
	{
		// Store the extra header info instead
		pt->t.chunkId = EXTRA_HEADER_INFO_FLAG | t->extraParentObjectId; // We save the parent object in the chunkId
		if(t->extraIsShrinkHeader) 
		{
		    pt->t.chunkId |= EXTRA_SHRINK_FLAG;
		}
		
		pt->t.objectId &= ~EXTRA_OBJECT_TYPE_MASK;
		pt->t.objectId |= (t->extraObjectType << EXTRA_OBJECT_TYPE_SHIFT);
		 
		if(t->extraObjectType == YAFFS_OBJECT_TYPE_HARDLINK)
		{
		   pt->t.byteCount = t->extraEquivalentObjectId;
		}
		else if(t->extraObjectType == YAFFS_OBJECT_TYPE_FILE)
		{
		   pt->t.byteCount = t->extraFileLength;
		}
		else
		{
		   pt->t.byteCount = 0;
		}
	}
	
	yaffs_DumpPackedTags2(pt);
	yaffs_DumpTags2(t);
	
	yaffs_ECCCalculateOther((unsigned char *)&pt->t,sizeof(yaffs_PackedTags2TagsPart),&pt->ecc);
	
}

void yaffs_UnpackTags2(yaffs_ExtendedTags *t, yaffs_PackedTags2 *pt)
{

	
	memset(t,0,sizeof(yaffs_ExtendedTags));
	
	yaffs_InitialiseTags(t);
	
	if(pt->t.sequenceNumber != 0xFFFFFFFF)
	{
		// Page is in use
		yaffs_ECCOther ecc;
		yaffs_ECCCalculateOther((unsigned char *)&pt->t,sizeof(yaffs_PackedTags2TagsPart),&ecc);
		t->eccResult = yaffs_ECCCorrectOther((unsigned char *)&pt->t,sizeof(yaffs_PackedTags2TagsPart),&pt->ecc,&ecc);
		t->blockBad = 0;
		t->chunkUsed = 1;
		t->objectId = pt->t.objectId;
		t->chunkId =  pt->t.chunkId;
		t->byteCount = pt->t.byteCount;
		t->chunkDeleted = 0;
		t->serialNumber = 0;
		t->sequenceNumber = pt->t.sequenceNumber;
		
		// Do extra header info stuff
		
		if(pt->t.chunkId & EXTRA_HEADER_INFO_FLAG)
		{
			t->chunkId = 0;
			t->byteCount = 0;
			
			t->extraHeaderInfoAvailable = 1;
			t->extraParentObjectId = pt->t.chunkId & (~(ALL_EXTRA_FLAGS));
			t->extraIsShrinkHeader =  (pt->t.chunkId & EXTRA_SHRINK_FLAG) ? 1 : 0;
			t->extraObjectType = pt->t.objectId >> EXTRA_OBJECT_TYPE_SHIFT;
			t->objectId &= ~EXTRA_OBJECT_TYPE_MASK;
			
			if(t->extraObjectType == YAFFS_OBJECT_TYPE_HARDLINK)
			{
			    t->extraEquivalentObjectId = pt->t.byteCount;
			}
			else 
			{
			    t->extraFileLength = pt->t.byteCount;
			}
		}
	}

	yaffs_DumpPackedTags2(pt);
	yaffs_DumpTags2(t);

}