ossimDdfrecord.cpp

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/******************************************************************************
 * Copied from "gdal" project. See licence below.
 *
 * Project:  ISO 8211 Access
 * Purpose:  Implements the DDFRecord class.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 1999, Frank Warmerdam
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ******************************************************************************
 * $Id: ossimDdfrecord.cpp 15833 2009-10-29 01:41:53Z eshirschorn $
 */

#include <cstring>
#include <ossim/imaging/ossimIso8211.h>
#include <ossim/base/ossimNotifyContext.h>
#include <ossim/base/ossimCplUtil.h>

// CPL_CVSID("$Id: ossimDdfrecord.cpp 15833 2009-10-29 01:41:53Z eshirschorn $");

static const size_t nLeaderSize = 24;

/************************************************************************/
/*                             DDFRecord()                              */
/************************************************************************/

ossimDDFRecord::ossimDDFRecord( ossimDDFModule * poModuleIn )

{
    poModule = poModuleIn;

    nReuseHeader = false;

    nFieldOffset = 0;

    nDataSize = 0;
    pachData = NULL;

    nFieldCount = 0;
    paoFields = NULL;

    bIsClone = false;

    _sizeFieldTag = 4;
    _sizeFieldPos = 0;
    _sizeFieldLength = 0;
}

/************************************************************************/
/*                             ~DDFRecord()                             */
/************************************************************************/

ossimDDFRecord::~ossimDDFRecord()

{
    Clear();

    if( bIsClone )
        poModule->RemoveCloneRecord( this );
}

/************************************************************************/
/*                                Dump()                                */
/************************************************************************/

void ossimDDFRecord::Dump( FILE * fp )

{
    fprintf( fp, "DDFRecord:\n" );
    fprintf( fp, "    nReuseHeader = %d\n", nReuseHeader );
    fprintf( fp, "    nDataSize = %d\n", nDataSize );
    fprintf( fp, 
             "    _sizeFieldLength=%d, _sizeFieldPos=%d, _sizeFieldTag=%d\n",
             _sizeFieldLength, _sizeFieldPos, _sizeFieldTag );

    for( int i = 0; i < nFieldCount; i++ )
    {
        paoFields[i].Dump( fp );
    }
}

/************************************************************************/
/*                                Read()                                */
/*                                                                      */
/*      Read a record of data from the file, and parse the header to    */
/*      build a field list for the record (or reuse the existing one    */
/*      if reusing headers).  It is expected that the file pointer      */
/*      will be positioned at the beginning of a data record.  It is    */
/*      the DDFModule's responsibility to do so.                        */
/*                                                                      */
/*      This method should only be called by the DDFModule class.       */
/************************************************************************/

int ossimDDFRecord::Read()

{
/* -------------------------------------------------------------------- */
/*      Redefine the record on the basis of the header if needed.       */
/*      As a side effect this will read the data for the record as well.*/
/* -------------------------------------------------------------------- */
    if( !nReuseHeader )
    {
        return( ReadHeader() );
    }

/* -------------------------------------------------------------------- */
/*      Otherwise we read just the data and carefully overlay it on     */
/*      the previous records data without disturbing the rest of the    */
/*      record.                                                         */
/* -------------------------------------------------------------------- */
    size_t      nReadBytes;

    nReadBytes = fread( pachData + nFieldOffset, 1,
                           nDataSize - nFieldOffset,
                           poModule->GetFP() );
    if( nReadBytes != (size_t) (nDataSize - nFieldOffset)
        && nReadBytes == 0
        && feof( poModule->GetFP() ) )
    {
        return false;
    }
    else if( nReadBytes != (size_t) (nDataSize - nFieldOffset) )
    {
        ossimNotify(ossimNotifyLevel_WARN)
           << "Data record is short on DDF file.\n" << std::endl;
        
        return false;
    }

    // notdef: eventually we may have to do something at this point to 
    // notify the DDFField's that their data values have changed. 
    
    return true;
}

/************************************************************************/
/*                               Write()                                */
/************************************************************************/

int ossimDDFRecord::Write()

{
    if( !ResetDirectory() )
        return false;
    
/* -------------------------------------------------------------------- */
/*      Prepare leader.                                                 */
/* -------------------------------------------------------------------- */
    char szLeader[nLeaderSize+1];

    memset( szLeader, ' ', nLeaderSize );

    sprintf( szLeader+0, "%05d",
             static_cast<int>(nDataSize + nLeaderSize) );
    szLeader[5] = ' ';
    szLeader[6] = 'D';
    
    sprintf( szLeader + 12, "%05d",
             static_cast<int>(nFieldOffset + nLeaderSize) );
    szLeader[17] = ' ';

    szLeader[20] = (char) ('0' + _sizeFieldLength);
    szLeader[21] = (char) ('0' + _sizeFieldPos);
    szLeader[22] = '0';
    szLeader[23] = (char) ('0' + _sizeFieldTag);

    /* notdef: lots of stuff missing */

/* -------------------------------------------------------------------- */
/*      Write the leader.                                               */
/* -------------------------------------------------------------------- */
    fwrite( szLeader, nLeaderSize, 1, poModule->GetFP() );

/* -------------------------------------------------------------------- */
/*      Write the remainder of the record.                              */
/* -------------------------------------------------------------------- */
    fwrite( pachData, nDataSize, 1, poModule->GetFP() );
    
    return true;
}

/************************************************************************/
/*                               Clear()                                */
/*                                                                      */
/*      Clear any information associated with the last header in        */
/*      preparation for reading a new header.                           */
/************************************************************************/

void ossimDDFRecord::Clear()

{
    if( paoFields != NULL )
        delete[] paoFields;

    paoFields = NULL;
    nFieldCount = 0;

    if( pachData != NULL )
        free( pachData );

    pachData = NULL;
    nDataSize = 0;
    nReuseHeader = false;
}

/************************************************************************/
/*                             ReadHeader()                             */
/*                                                                      */
/*      This perform the header reading and parsing job for the         */
/*      Read() method.  It reads the header, and builds a field         */
/*      list.                                                           */
/************************************************************************/

int ossimDDFRecord::ReadHeader()

{
/* -------------------------------------------------------------------- */
/*      Clear any existing information.                                 */
/* -------------------------------------------------------------------- */
    Clear();
    
/* -------------------------------------------------------------------- */
/*      Read the 24 byte leader.                                        */
/* -------------------------------------------------------------------- */
    char        achLeader[nLeaderSize];
    int         nReadBytes;

    nReadBytes = (int)fread(achLeader,1,(int)nLeaderSize,poModule->GetFP());
    if( nReadBytes == 0 && feof( poModule->GetFP() ) )
    {
        return false;
    }
    else if( nReadBytes != (int) nLeaderSize )
    {
        ossimNotify(ossimNotifyLevel_WARN)
           << "Leader is short on DDF file." << std::endl;
        
        return false;
    }

/* -------------------------------------------------------------------- */
/*      Extract information from leader.                                */
/* -------------------------------------------------------------------- */
    int         _recLength, _fieldAreaStart;
    char        _leaderIden;
    
    _recLength                    = ossimDDFScanInt( achLeader+0, 5 );
    _leaderIden                   = achLeader[6];
    _fieldAreaStart               = ossimDDFScanInt(achLeader+12,5);
    
    _sizeFieldLength = achLeader[20] - '0';
    _sizeFieldPos = achLeader[21] - '0';
    _sizeFieldTag = achLeader[23] - '0';

    if( _sizeFieldLength < 0 || _sizeFieldLength > 9 
        || _sizeFieldPos < 0 || _sizeFieldPos > 9
        || _sizeFieldTag < 0 || _sizeFieldTag > 9 )
    {
        ossimNotify(ossimNotifyLevel_WARN)
           << "ISO8211 record leader appears to be corrupt." << std::endl;
        return false;
    }

    if( _leaderIden == 'R' )
        nReuseHeader = true;

    nFieldOffset = _fieldAreaStart - nLeaderSize;

/* -------------------------------------------------------------------- */
/*      Is there anything seemly screwy about this record?              */
/* -------------------------------------------------------------------- */
    if(( _recLength < 24 || _recLength > 100000000
         || _fieldAreaStart < 24 || _fieldAreaStart > 100000 )
       && (_recLength != 0))
    {
        ossimNotify(ossimNotifyLevel_WARN)
           << "Data record appears to be corrupt on DDF file.\n"
           << " -- ensure that the files were uncompressed without modifying\n"
           << "carriage return/linefeeds (by default WINZIP does this)."
           << std::endl;
        
        return false;
    }

/* ==================================================================== */
/*      Handle the normal case with the record length available.        */
/* ==================================================================== */
    if(_recLength != 0) {
/* -------------------------------------------------------------------- */
/*      Read the remainder of the record.                               */
/* -------------------------------------------------------------------- */
        nDataSize = _recLength - nLeaderSize;
        pachData = (char *) malloc(nDataSize);

        if( fread( pachData, 1, nDataSize, poModule->GetFP()) !=
            (size_t) nDataSize )
        {
            ossimNotify(ossimNotifyLevel_WARN)
               << "Data record is short on DDF file."
               << std::endl;
          
            return false;
        }

/* -------------------------------------------------------------------- */
/*      If we don't find a field terminator at the end of the record    */
/*      we will read extra bytes till we get to it.                     */
/* -------------------------------------------------------------------- */
        while( pachData[nDataSize-1] != OSSIM_DDF_FIELD_TERMINATOR )
        {
            nDataSize++;
            pachData = (char *) ossimCPLRealloc(pachData,nDataSize);
            
            if( fread( pachData + nDataSize - 1, 1, 1, poModule->GetFP() )
                != 1 )
            {
                ossimNotify(ossimNotifyLevel_WARN)
                   << "Data record is short on DDF file."
                   << std::endl;
                
                return false;
            }
            ossimNotify(ossimNotifyLevel_DEBUG)
               << "Didn't find field terminator, read one more byte."
               << std::endl;
        }

/* -------------------------------------------------------------------- */
/*      Loop over the directory entries, making a pass counting them.   */
/* -------------------------------------------------------------------- */
        int         i;
        int         nFieldEntryWidth;
      
        nFieldEntryWidth = _sizeFieldLength + _sizeFieldPos + _sizeFieldTag;
        nFieldCount = 0;
        for( i = 0; i < nDataSize; i += nFieldEntryWidth )
        {
            if( pachData[i] == OSSIM_DDF_FIELD_TERMINATOR )
                break;
          
            nFieldCount++;
        }
    
/* -------------------------------------------------------------------- */
/*      Allocate, and read field definitions.                           */
/* -------------------------------------------------------------------- */
        paoFields = new ossimDDFField[nFieldCount];
    
        for( i = 0; i < nFieldCount; i++ )
        {
            char    szTag[128];
            int     nEntryOffset = i*nFieldEntryWidth;
            int     nFieldLength, nFieldPos;
          
/* -------------------------------------------------------------------- */
/*      Read the position information and tag.                          */
/* -------------------------------------------------------------------- */
            strncpy( szTag, pachData+nEntryOffset, _sizeFieldTag );
            szTag[_sizeFieldTag] = '\0';
          
            nEntryOffset += _sizeFieldTag;
            nFieldLength = ossimDDFScanInt( pachData+nEntryOffset, _sizeFieldLength );
          
            nEntryOffset += _sizeFieldLength;
            nFieldPos = ossimDDFScanInt( pachData+nEntryOffset, _sizeFieldPos );
          
/* -------------------------------------------------------------------- */
/*      Find the corresponding field in the module directory.           */
/* -------------------------------------------------------------------- */
            ossimDDFFieldDefn    *poFieldDefn = poModule->FindFieldDefn( szTag );
          
            if( poFieldDefn == NULL )
            {
                ossimNotify(ossimNotifyLevel_WARN)
                   << "Undefined field `%s' encountered in data record."
                   << szTag << std::endl;
                return false;
            }

/* -------------------------------------------------------------------- */
/*      Assign info the DDFField.                                       */
/* -------------------------------------------------------------------- */
            paoFields[i].Initialize( poFieldDefn, 
                                     pachData + _fieldAreaStart + nFieldPos - nLeaderSize,
                                     nFieldLength );
        }
      
        return true;
    }
/* ==================================================================== */
/*      Handle the exceptional case where the record length is          */
/*      zero.  In this case we have to read all the data based on       */
/*      the size of data items as per ISO8211 spec Annex C, 1.5.1.      */
/*                                                                      */
/*      See Bugzilla bug 181 and test with file US4CN21M.000.           */
/* ==================================================================== */
    else {
        ossimNotify(ossimNotifyLevel_WARN)
           << "Record with zero length, use variant (C.1.5.1) logic."
           << std::endl;

        /* ----------------------------------------------------------------- */
        /*   _recLength == 0, handle the large record.                       */
        /*                                                                   */
        /*   Read the remainder of the record.                               */
        /* ----------------------------------------------------------------- */
        nDataSize = 0;
        pachData = NULL;

        /* ----------------------------------------------------------------- */
        /*   Loop over the directory entries, making a pass counting them.   */
        /* ----------------------------------------------------------------- */
        int nFieldEntryWidth = _sizeFieldLength + _sizeFieldPos + _sizeFieldTag;
        nFieldCount = 0;
        int i=0;
        char *tmpBuf = (char*)malloc(nFieldEntryWidth);
      
        // while we're not at the end, store this entry,
        // and keep on reading...
        do {
            // read an Entry:
            if(nFieldEntryWidth != 
               (int) fread(tmpBuf, 1, nFieldEntryWidth, poModule->GetFP())) {
                ossimNotify(ossimNotifyLevel_WARN)
                   << "Data record is short on DDF file." << std::endl;
                return false;
            }
      
            // move this temp buffer into more permanent storage:
            char *newBuf = (char*)malloc(nDataSize+nFieldEntryWidth);
            if(pachData!=NULL) {
                memcpy(newBuf, pachData, nDataSize);
                free(pachData);
            }
            memcpy(&newBuf[nDataSize], tmpBuf, nFieldEntryWidth);
            pachData = newBuf;
            nDataSize += nFieldEntryWidth;

            if(OSSIM_DDF_FIELD_TERMINATOR != tmpBuf[0]) {
                nFieldCount++;
            }
        }
        while(OSSIM_DDF_FIELD_TERMINATOR != tmpBuf[0]);

        // Now, rewind a little.  Only the TERMINATOR should have been read:
        int rewindSize = nFieldEntryWidth - 1;
        FILE *fp = poModule->GetFP();
        long pos = ftell(fp) - rewindSize;
        fseek(fp, pos, SEEK_SET);
        nDataSize -= rewindSize;

        // --------------------------------------------------------------------
        // Okay, now let's populate the heck out of pachData...
        // --------------------------------------------------------------------
        for(i=0; i<nFieldCount; i++) {
            int nEntryOffset = (i*nFieldEntryWidth) + _sizeFieldTag;
            int nFieldLength = ossimDDFScanInt(pachData + nEntryOffset,
                                          _sizeFieldLength);
            char *tmpBuf = (char*)malloc(nFieldLength);

            // read an Entry:
            if(nFieldLength != 
               (int) fread(tmpBuf, 1, nFieldLength, poModule->GetFP())) {
                ossimNotify(ossimNotifyLevel_WARN)
                   << "Data record is short on DDF file." << std::endl;
                return false;
            }
      
            // move this temp buffer into more permanent storage:
            char *newBuf = (char*)malloc(nDataSize+nFieldLength);
            memcpy(newBuf, pachData, nDataSize);
            free(pachData);
            memcpy(&newBuf[nDataSize], tmpBuf, nFieldLength);
            free(tmpBuf);
            pachData = newBuf;
            nDataSize += nFieldLength;
        }
    
        /* ----------------------------------------------------------------- */
        /*     Allocate, and read field definitions.                         */
        /* ----------------------------------------------------------------- */
        paoFields = new ossimDDFField[nFieldCount];
      
        for( i = 0; i < nFieldCount; i++ )
        {
            char    szTag[128];
            int     nEntryOffset = i*nFieldEntryWidth;
            int     nFieldLength, nFieldPos;
          
            /* ------------------------------------------------------------- */
            /* Read the position information and tag.                        */
            /* ------------------------------------------------------------- */
            strncpy( szTag, pachData+nEntryOffset, _sizeFieldTag );
            szTag[_sizeFieldTag] = '\0';
          
            nEntryOffset += _sizeFieldTag;
            nFieldLength = ossimDDFScanInt( pachData+nEntryOffset, _sizeFieldLength );
          
            nEntryOffset += _sizeFieldLength;
            nFieldPos = ossimDDFScanInt( pachData+nEntryOffset, _sizeFieldPos );
          
            /* ------------------------------------------------------------- */
            /* Find the corresponding field in the module directory.         */
            /* ------------------------------------------------------------- */
            ossimDDFFieldDefn    *poFieldDefn = poModule->FindFieldDefn( szTag );
          
            if( poFieldDefn == NULL )
            {
                ossimNotify(ossimNotifyLevel_WARN)
                   << "Undefined field `%s' encountered in data record."
                   << szTag << std::endl;
                return false;
            }

            /* ------------------------------------------------------------- */
            /* Assign info the DDFField.                                     */
            /* ------------------------------------------------------------- */

            paoFields[i].Initialize( poFieldDefn, 
                                     pachData + _fieldAreaStart
                                     + nFieldPos - nLeaderSize,
                                     nFieldLength );
        }
      
        return true;
    }
}

/************************************************************************/
/*                             FindField()                              */
/************************************************************************/

ossimDDFField * ossimDDFRecord::FindField( const char * pszName, int iFieldIndex )

{
    for( int i = 0; i < nFieldCount; i++ )
    {
       ossimString s = paoFields[i].GetFieldDefn()->GetName();
        if( s == pszName)
        {
            if( iFieldIndex == 0 )
                return paoFields + i;
            else
                iFieldIndex--;
        }
    }

    return NULL;
}

/************************************************************************/
/*                              GetField()                              */
/************************************************************************/

ossimDDFField *ossimDDFRecord::GetField( int i )

{
    if( i < 0 || i >= nFieldCount )
        return NULL;
    else
        return paoFields + i;
}

/************************************************************************/
/*                           GetIntSubfield()                           */
/************************************************************************/

int ossimDDFRecord::GetIntSubfield( const char * pszField, int iFieldIndex,
                               const char * pszSubfield, int iSubfieldIndex,
                               int * pnSuccess )

{
    ossimDDFField    *poField;
    int         nDummyErr;

    if( pnSuccess == NULL )
        pnSuccess = &nDummyErr;

    *pnSuccess = false;
            
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return 0;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    ossimDDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return 0;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nBytesRemaining;
    
    const char *pachData = poField->GetSubfieldData(poSFDefn,
                                                    &nBytesRemaining,
                                                    iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Return the extracted value.                                     */
/* -------------------------------------------------------------------- */
    *pnSuccess = true;

    return( poSFDefn->ExtractIntData( pachData, nBytesRemaining, NULL ) );
}

/************************************************************************/
/*                          GetFloatSubfield()                          */
/************************************************************************/

double ossimDDFRecord::GetFloatSubfield( const char * pszField, int iFieldIndex,
                                 const char * pszSubfield, int iSubfieldIndex,
                                    int * pnSuccess )

{
    ossimDDFField    *poField;
    int         nDummyErr;

    if( pnSuccess == NULL )
        pnSuccess = &nDummyErr;

    *pnSuccess = false;
            
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return 0;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    ossimDDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return 0;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nBytesRemaining;
    
    const char *pachData = poField->GetSubfieldData(poSFDefn,
                                                    &nBytesRemaining,
                                                    iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Return the extracted value.                                     */
/* -------------------------------------------------------------------- */
    *pnSuccess = true;

    return( poSFDefn->ExtractFloatData( pachData, nBytesRemaining, NULL ) );
}

/************************************************************************/
/*                         GetStringSubfield()                          */
/************************************************************************/

const char *
ossimDDFRecord::GetStringSubfield( const char * pszField, int iFieldIndex,
                              const char * pszSubfield, int iSubfieldIndex,
                              int * pnSuccess )

{
    ossimDDFField    *poField;
    int         nDummyErr;

    if( pnSuccess == NULL )
        pnSuccess = &nDummyErr;

    *pnSuccess = false;
            
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    ossimDDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nBytesRemaining;
    
    const char *pachData = poField->GetSubfieldData(poSFDefn,
                                                    &nBytesRemaining,
                                                    iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Return the extracted value.                                     */
/* -------------------------------------------------------------------- */
    *pnSuccess = true;

    return( poSFDefn->ExtractStringData( pachData, nBytesRemaining, NULL ) );
}

/************************************************************************/
/*                               Clone()                                */
/************************************************************************/

ossimDDFRecord * ossimDDFRecord::Clone()

{
    ossimDDFRecord   *poNR;

    poNR = new ossimDDFRecord( poModule );

    poNR->nReuseHeader = false;
    poNR->nFieldOffset = nFieldOffset;
    
    poNR->nDataSize = nDataSize;
    poNR->pachData = (char *) malloc(nDataSize);
    memcpy( poNR->pachData, pachData, nDataSize );
    
    poNR->nFieldCount = nFieldCount;
    poNR->paoFields = new ossimDDFField[nFieldCount];
    for( int i = 0; i < nFieldCount; i++ )
    {
        int     nOffset;

        nOffset = (paoFields[i].GetData() - pachData);
        poNR->paoFields[i].Initialize( paoFields[i].GetFieldDefn(),
                                       poNR->pachData + nOffset,
                                       paoFields[i].GetDataSize() );
    }
    
    poNR->bIsClone = true;
    poModule->AddCloneRecord( poNR );

    return poNR;
}

/************************************************************************/
/*                              CloneOn()                               */
/************************************************************************/

ossimDDFRecord *ossimDDFRecord::CloneOn( ossimDDFModule *poTargetModule )

{
/* -------------------------------------------------------------------- */
/*      Verify that all fields have a corresponding field definition    */
/*      on the target module.                                           */
/* -------------------------------------------------------------------- */
    int         i;

    for( i = 0; i < nFieldCount; i++ )
    {
        ossimDDFFieldDefn    *poDefn = paoFields[i].GetFieldDefn();

        if( poTargetModule->FindFieldDefn( poDefn->GetName() ) == NULL )
            return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Create a clone.                                                 */
/* -------------------------------------------------------------------- */
    ossimDDFRecord   *poClone;

    poClone = Clone();

/* -------------------------------------------------------------------- */
/*      Update all internal information to reference other module.      */
/* -------------------------------------------------------------------- */
    for( i = 0; i < nFieldCount; i++ )
    {
        ossimDDFField        *poField = poClone->paoFields+i;
        ossimDDFFieldDefn    *poDefn;

        poDefn = poTargetModule->FindFieldDefn( 
            poField->GetFieldDefn()->GetName() );
        
        poField->Initialize( poDefn, poField->GetData(), 
                             poField->GetDataSize() );
    }

    poModule->RemoveCloneRecord( poClone );
    poClone->poModule = poTargetModule;
    poTargetModule->AddCloneRecord( poClone );

    return poClone;
}


/************************************************************************/
/*                            DeleteField()                             */
/************************************************************************/

int ossimDDFRecord::DeleteField( ossimDDFField *poTarget )

{
    int         iTarget, i;

/* -------------------------------------------------------------------- */
/*      Find which field we are to delete.                              */
/* -------------------------------------------------------------------- */
    for( iTarget = 0; iTarget < nFieldCount; iTarget++ )
    {
        if( paoFields + iTarget == poTarget )
            break;
    }

    if( iTarget == nFieldCount )
        return false;

/* -------------------------------------------------------------------- */
/*      Change the target fields data size to zero.  This takes care    */
/*      of repacking the data array, and updating all the following     */
/*      field data pointers.                                            */
/* -------------------------------------------------------------------- */
    ResizeField( poTarget, 0 );

/* -------------------------------------------------------------------- */
/*      remove the target field, moving down all the other fields       */
/*      one step in the field list.                                     */
/* -------------------------------------------------------------------- */
    for( i = iTarget; i < nFieldCount-1; i++ )
    {
        paoFields[i] = paoFields[i+1];
    }

    nFieldCount--;

    return true;
}

/************************************************************************/
/*                            ResizeField()                             */
/************************************************************************/

int ossimDDFRecord::ResizeField( ossimDDFField *poField, int nNewDataSize )

{
    int         iTarget, i;
    int         nBytesToMove;

/* -------------------------------------------------------------------- */
/*      Find which field we are to resize.                              */
/* -------------------------------------------------------------------- */
    for( iTarget = 0; iTarget < nFieldCount; iTarget++ )
    {
        if( paoFields + iTarget == poField )
            break;
    }

    if( iTarget == nFieldCount )
    {
       // CPLAssert( false );
        return false;
    }

/* -------------------------------------------------------------------- */
/*      Reallocate the data buffer accordingly.                         */
/* -------------------------------------------------------------------- */
    int nBytesToAdd = nNewDataSize - poField->GetDataSize();
    const char *pachOldData = pachData;

    // Don't realloc things smaller ... we will cut off some data.
    if( nBytesToAdd > 0 )
        pachData = (char *) ossimCPLRealloc(pachData, nDataSize + nBytesToAdd );

    nDataSize += nBytesToAdd;

/* -------------------------------------------------------------------- */
/*      How much data needs to be shifted up or down after this field?  */
/* -------------------------------------------------------------------- */
    nBytesToMove = nDataSize 
        - (poField->GetData()+poField->GetDataSize()-pachOldData+nBytesToAdd);

/* -------------------------------------------------------------------- */
/*      Update fields to point into newly allocated buffer.             */
/* -------------------------------------------------------------------- */
    for( i = 0; i < nFieldCount; i++ )
    {
        int     nOffset;

        nOffset = paoFields[i].GetData() - pachOldData;
        paoFields[i].Initialize( paoFields[i].GetFieldDefn(), 
                                 pachData + nOffset, 
                                 paoFields[i].GetDataSize() );
    }

/* -------------------------------------------------------------------- */
/*      Shift the data beyond this field up or down as needed.          */
/* -------------------------------------------------------------------- */
    if( nBytesToMove > 0 )
        memmove( (char *)poField->GetData()+poField->GetDataSize()+nBytesToAdd,
                 (char *)poField->GetData()+poField->GetDataSize(), 
                 nBytesToMove );
             
/* -------------------------------------------------------------------- */
/*      Update the target fields info.                                  */
/* -------------------------------------------------------------------- */
    poField->Initialize( poField->GetFieldDefn(),
                         poField->GetData(), 
                         poField->GetDataSize() + nBytesToAdd );

/* -------------------------------------------------------------------- */
/*      Shift all following fields down, and update their data          */
/*      locations.                                                      */
/* -------------------------------------------------------------------- */
    if( nBytesToAdd < 0 )
    {
        for( i = iTarget+1; i < nFieldCount; i++ )
        {
            char *pszOldDataLocation;

            pszOldDataLocation = (char *) paoFields[i].GetData();

            paoFields[i].Initialize( paoFields[i].GetFieldDefn(), 
                                     pszOldDataLocation + nBytesToAdd,
                                     paoFields[i].GetDataSize() ); 
        }
    }
    else
    {
        for( i = nFieldCount-1; i > iTarget; i-- )
        {
            char *pszOldDataLocation;

            pszOldDataLocation = (char *) paoFields[i].GetData();

            paoFields[i].Initialize( paoFields[i].GetFieldDefn(), 
                                     pszOldDataLocation + nBytesToAdd,
                                     paoFields[i].GetDataSize() ); 
        }
    }

    return true;
}

/************************************************************************/
/*                              AddField()                              */
/************************************************************************/

ossimDDFField *ossimDDFRecord::AddField( ossimDDFFieldDefn *poDefn )

{
/* -------------------------------------------------------------------- */
/*      Reallocate the fields array larger by one, and initialize       */
/*      the new field.                                                  */
/* -------------------------------------------------------------------- */
    ossimDDFField    *paoNewFields;

    paoNewFields = new ossimDDFField[nFieldCount+1];
    if( nFieldCount > 0 )
    {
        memcpy( paoNewFields, paoFields, sizeof(ossimDDFField) * nFieldCount );
        delete[] paoFields;
    }
    paoFields = paoNewFields;
    nFieldCount++;

/* -------------------------------------------------------------------- */
/*      Initialize the new field properly.                              */
/* -------------------------------------------------------------------- */
    if( nFieldCount == 1 )
    {
        paoFields[0].Initialize( poDefn, GetData(), 0 );
    }
    else
    {
        paoFields[nFieldCount-1].Initialize( 
            poDefn, 
            paoFields[nFieldCount-2].GetData()
            + paoFields[nFieldCount-2].GetDataSize(), 
            0 );
    }

/* -------------------------------------------------------------------- */
/*      Initialize field.                                               */
/* -------------------------------------------------------------------- */
    CreateDefaultFieldInstance( paoFields + nFieldCount-1, 0 );

    return paoFields + (nFieldCount - 1);
}

/************************************************************************/
/*                            SetFieldRaw()                             */
/************************************************************************/

int
ossimDDFRecord::SetFieldRaw( ossimDDFField *poField, int iIndexWithinField,
                        const char *pachRawData, int nRawDataSize )

{
    int         iTarget, nRepeatCount;

/* -------------------------------------------------------------------- */
/*      Find which field we are to update.                              */
/* -------------------------------------------------------------------- */
    for( iTarget = 0; iTarget < nFieldCount; iTarget++ )
    {
        if( paoFields + iTarget == poField )
            break;
    }

    if( iTarget == nFieldCount )
        return false;

    nRepeatCount = poField->GetRepeatCount();

    if( iIndexWithinField < 0 || iIndexWithinField > nRepeatCount )
        return false;

/* -------------------------------------------------------------------- */
/*      Are we adding an instance?  This is easier and different        */
/*      than replacing an existing instance.                            */
/* -------------------------------------------------------------------- */
    if( iIndexWithinField == nRepeatCount 
        || !poField->GetFieldDefn()->IsRepeating() )
    {
        char    *pachFieldData;
        int     nOldSize;

        if( !poField->GetFieldDefn()->IsRepeating() && iIndexWithinField != 0 )
            return false;

        nOldSize = poField->GetDataSize();
        if( nOldSize == 0 )
            nOldSize++; // for added DDF_FIELD_TERMINATOR. 

        if( !ResizeField( poField, nOldSize + nRawDataSize ) )
            return false;

        pachFieldData = (char *) poField->GetData();
        memcpy( pachFieldData + nOldSize - 1, 
                pachRawData, nRawDataSize );
        pachFieldData[nOldSize+nRawDataSize-1] = OSSIM_DDF_FIELD_TERMINATOR;

        return true;
    }

/* -------------------------------------------------------------------- */
/*      Get a pointer to the start of the existing data for this        */
/*      iteration of the field.                                         */
/* -------------------------------------------------------------------- */
    const char *pachWrkData;
    int         nInstanceSize;

    // We special case this to avoid alot of warnings when initializing 
    // the field the first time.
    if( poField->GetDataSize() == 0 )
    {
        pachWrkData = poField->GetData();
        nInstanceSize = 0;
    }
    else
    {
        pachWrkData = poField->GetInstanceData( iIndexWithinField, 
                                                &nInstanceSize );
    }

/* -------------------------------------------------------------------- */
/*      Create new image of this whole field.                           */
/* -------------------------------------------------------------------- */
    char        *pachNewImage;
    int         nPreBytes, nPostBytes, nNewFieldSize;

    nNewFieldSize = poField->GetDataSize() - nInstanceSize + nRawDataSize;

    pachNewImage = (char *) malloc(nNewFieldSize);

    nPreBytes = pachWrkData - poField->GetData();
    nPostBytes = poField->GetDataSize() - nPreBytes - nInstanceSize;

    memcpy( pachNewImage, poField->GetData(), nPreBytes );
    memcpy( pachNewImage + nPreBytes + nRawDataSize, 
            poField->GetData() + nPreBytes + nInstanceSize,
            nPostBytes );
    memcpy( pachNewImage + nPreBytes, pachRawData, nRawDataSize );

/* -------------------------------------------------------------------- */
/*      Resize the field to the desired new size.                       */
/* -------------------------------------------------------------------- */
    ResizeField( poField, nNewFieldSize );

    memcpy( (void *) poField->GetData(), pachNewImage, nNewFieldSize );
    free( pachNewImage );

    return true;
}

/************************************************************************/
/*                           UpdateFieldRaw()                           */
/************************************************************************/

int
ossimDDFRecord::UpdateFieldRaw( ossimDDFField *poField, int iIndexWithinField,
                           int nStartOffset, int nOldSize, 
                           const char *pachRawData, int nRawDataSize )

{
    int         iTarget, nRepeatCount;

/* -------------------------------------------------------------------- */
/*      Find which field we are to update.                              */
/* -------------------------------------------------------------------- */
    for( iTarget = 0; iTarget < nFieldCount; iTarget++ )
    {
        if( paoFields + iTarget == poField )
            break;
    }

    if( iTarget == nFieldCount )
        return false;

    nRepeatCount = poField->GetRepeatCount();

    if( iIndexWithinField < 0 || iIndexWithinField >= nRepeatCount )
        return false;

/* -------------------------------------------------------------------- */
/*      Figure out how much pre and post data there is.                 */
/* -------------------------------------------------------------------- */
    char *pachWrkData;
    int         nInstanceSize, nPostBytes, nPreBytes;
        
    pachWrkData = (char *) poField->GetInstanceData( iIndexWithinField, 
                                                     &nInstanceSize );
    nPreBytes = pachWrkData - poField->GetData() + nStartOffset;
    nPostBytes = poField->GetDataSize() - nPreBytes - nOldSize;

/* -------------------------------------------------------------------- */
/*      If we aren't changing the size, just copy over the existing     */
/*      data.                                                           */
/* -------------------------------------------------------------------- */
    if( nOldSize == nRawDataSize )
    {
        memcpy( pachWrkData + nStartOffset, pachRawData, nRawDataSize );
        return true;
    }

/* -------------------------------------------------------------------- */
/*      If we are shrinking, move in the new data, and shuffle down     */
/*      the old before resizing.                                        */
/* -------------------------------------------------------------------- */
    if( nRawDataSize < nOldSize )
    {
        memcpy( ((char*) poField->GetData()) + nPreBytes, 
                pachRawData, nRawDataSize );
        memmove( ((char *) poField->GetData()) + nPreBytes + nRawDataSize, 
                 ((char *) poField->GetData()) + nPreBytes + nOldSize, 
                 nPostBytes );
    }

/* -------------------------------------------------------------------- */
/*      Resize the whole buffer.                                        */
/* -------------------------------------------------------------------- */
    if( !ResizeField( poField, 
                      poField->GetDataSize() - nOldSize + nRawDataSize ) )
        return false;

/* -------------------------------------------------------------------- */
/*      If we growing the buffer, shuffle up the post data, and         */
/*      move in our new values.                                         */
/* -------------------------------------------------------------------- */
    if( nRawDataSize >= nOldSize )
    {
        memmove( ((char *) poField->GetData()) + nPreBytes + nRawDataSize, 
                 ((char *) poField->GetData()) + nPreBytes + nOldSize, 
                 nPostBytes );
        memcpy( ((char*) poField->GetData()) + nPreBytes, 
                pachRawData, nRawDataSize );
    }

    return true;
}

/************************************************************************/
/*                           ResetDirectory()                           */
/*                                                                      */
/*      Re-prepares the directory information for the record.           */
/************************************************************************/

int ossimDDFRecord::ResetDirectory()

{
    int iField;

/* -------------------------------------------------------------------- */
/*      Eventually we should try to optimize the size of offset and     */
/*      field length.  For now we will use 5 for each which is          */
/*      pretty big.                                                     */
/* -------------------------------------------------------------------- */
    _sizeFieldPos = 5;
    _sizeFieldLength = 5;

/* -------------------------------------------------------------------- */
/*      Compute how large the directory needs to be.                    */
/* -------------------------------------------------------------------- */
    int nEntrySize, nDirSize;

    nEntrySize = _sizeFieldPos + _sizeFieldLength + _sizeFieldTag;
    nDirSize = nEntrySize * nFieldCount + 1;

/* -------------------------------------------------------------------- */
/*      If the directory size is different than what is currently       */
/*      reserved for it, we must resize.                                */
/* -------------------------------------------------------------------- */
    if( nDirSize != nFieldOffset )
    {
        char *pachNewData;
        int  nNewDataSize;

        nNewDataSize = nDataSize - nFieldOffset + nDirSize;
        pachNewData = (char *) malloc(nNewDataSize);
        memcpy( pachNewData + nDirSize, 
                pachData + nFieldOffset, 
                nNewDataSize - nDirSize );
     
        for( iField = 0; iField < nFieldCount; iField++ )
        {
            int nOffset;
            ossimDDFField *poField = GetField( iField );

            nOffset = poField->GetData() - pachData - nFieldOffset + nDirSize;
            poField->Initialize( poField->GetFieldDefn(), 
                                 pachNewData + nOffset, 
                                 poField->GetDataSize() );
        }

        free( pachData );
        pachData = pachNewData;
        nDataSize = nNewDataSize;
        nFieldOffset = nDirSize;
    }

/* -------------------------------------------------------------------- */
/*      Now set each directory entry.                                   */
/* -------------------------------------------------------------------- */
    for( iField = 0; iField < nFieldCount; iField++ )
    {
        ossimDDFField *poField = GetField( iField );
        ossimDDFFieldDefn *poDefn = poField->GetFieldDefn();
        char      szFormat[128];

        sprintf( szFormat, "%%%ds%%0%dd%%0%dd", 
                 _sizeFieldTag, _sizeFieldLength, _sizeFieldPos );

        sprintf( pachData + nEntrySize * iField, szFormat, 
                 poDefn->GetName(), poField->GetDataSize(),
                 poField->GetData() - pachData - nFieldOffset );
    }

    pachData[nEntrySize * nFieldCount] = OSSIM_DDF_FIELD_TERMINATOR;
        
    return true;
}

/************************************************************************/
/*                     CreateDefaultFieldInstance()                     */
/************************************************************************/

int ossimDDFRecord::CreateDefaultFieldInstance( ossimDDFField *poField, 
                                           int iIndexWithinField )

{
    int nRawSize, nSuccess;
    char *pachRawData;

    pachRawData = poField->GetFieldDefn()->GetDefaultValue( &nRawSize );
    if( pachRawData == NULL )
        return false;

    nSuccess = SetFieldRaw( poField, iIndexWithinField, pachRawData, nRawSize);

    free( pachRawData );

    return nSuccess;
}

/************************************************************************/
/*                         SetStringSubfield()                          */
/************************************************************************/

int ossimDDFRecord::SetStringSubfield( const char *pszField, int iFieldIndex, 
                                  const char *pszSubfield, int iSubfieldIndex,
                                  const char *pszValue, int nValueLength )

{
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    ossimDDFField *poField; 

    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return false;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    ossimDDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return false;

/* -------------------------------------------------------------------- */
/*      How long will the formatted value be?                           */
/* -------------------------------------------------------------------- */
    int nFormattedLen;

    if( !poSFDefn->FormatStringValue( NULL, 0, &nFormattedLen, pszValue,
                                      nValueLength ) )
        return false;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nMaxBytes;
    char *pachSubfieldData = (char *) 
        poField->GetSubfieldData(poSFDefn, &nMaxBytes,
                                 iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Add new instance if we have run out of data.                    */
/* -------------------------------------------------------------------- */
    if( nMaxBytes == 0 
        || (nMaxBytes == 1 && pachSubfieldData[0] == OSSIM_DDF_FIELD_TERMINATOR) )
    {
        CreateDefaultFieldInstance( poField, iSubfieldIndex );

        // Refetch.
        pachSubfieldData = (char *) 
            poField->GetSubfieldData(poSFDefn, &nMaxBytes,
                                     iSubfieldIndex);
    }

/* -------------------------------------------------------------------- */
/*      If the new length matches the existing length, just overlay     */
/*      and return.                                                     */
/* -------------------------------------------------------------------- */
    int nExistingLength;

    poSFDefn->GetDataLength( pachSubfieldData, nMaxBytes, &nExistingLength );

    if( nExistingLength == nFormattedLen )
    {
        return poSFDefn->FormatStringValue( pachSubfieldData, nFormattedLen,
                                            NULL, pszValue, nValueLength );
    }

/* -------------------------------------------------------------------- */
/*      We will need to resize the raw data.                            */
/* -------------------------------------------------------------------- */
    const char *pachFieldInstData;
    int         nInstanceSize, nStartOffset, nSuccess;
    char *pachNewData;

    pachFieldInstData = poField->GetInstanceData( iFieldIndex,
                                                  &nInstanceSize );

    nStartOffset = pachSubfieldData - pachFieldInstData;

    pachNewData = (char *) malloc(nFormattedLen);
    poSFDefn->FormatStringValue( pachNewData, nFormattedLen, NULL, 
                                 pszValue, nValueLength );
    
    nSuccess = UpdateFieldRaw( poField, iFieldIndex,
                               nStartOffset, nExistingLength, 
                               pachNewData, nFormattedLen );

    free( pachNewData );

    return nSuccess;
}

/************************************************************************/
/*                           SetIntSubfield()                           */
/************************************************************************/

int ossimDDFRecord::SetIntSubfield( const char *pszField, int iFieldIndex, 
                               const char *pszSubfield, int iSubfieldIndex,
                               int nNewValue )

{
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    ossimDDFField *poField; 

    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return false;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    ossimDDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return false;

/* -------------------------------------------------------------------- */
/*      How long will the formatted value be?                           */
/* -------------------------------------------------------------------- */
    int nFormattedLen;

    if( !poSFDefn->FormatIntValue( NULL, 0, &nFormattedLen, nNewValue ) )
        return false;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nMaxBytes;
    char *pachSubfieldData = (char *) 
        poField->GetSubfieldData(poSFDefn, &nMaxBytes,
                                 iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Add new instance if we have run out of data.                    */
/* -------------------------------------------------------------------- */
    if( nMaxBytes == 0 
        || (nMaxBytes == 1 && pachSubfieldData[0] == OSSIM_DDF_FIELD_TERMINATOR) )
    {
        CreateDefaultFieldInstance( poField, iSubfieldIndex );

        // Refetch.
        pachSubfieldData = (char *) 
            poField->GetSubfieldData(poSFDefn, &nMaxBytes,
                                     iSubfieldIndex);
    }

/* -------------------------------------------------------------------- */
/*      If the new length matches the existing length, just overlay     */
/*      and return.                                                     */
/* -------------------------------------------------------------------- */
    int nExistingLength;

    poSFDefn->GetDataLength( pachSubfieldData, nMaxBytes, &nExistingLength );

    if( nExistingLength == nFormattedLen )
    {
        return poSFDefn->FormatIntValue( pachSubfieldData, nFormattedLen,
                                         NULL, nNewValue );
    }

/* -------------------------------------------------------------------- */
/*      We will need to resize the raw data.                            */
/* -------------------------------------------------------------------- */
    const char *pachFieldInstData;
    int         nInstanceSize, nStartOffset, nSuccess;
    char *pachNewData;

    pachFieldInstData = poField->GetInstanceData( iFieldIndex,
                                                  &nInstanceSize );

    nStartOffset = pachSubfieldData - pachFieldInstData;

    pachNewData = (char *) malloc(nFormattedLen);
    poSFDefn->FormatIntValue( pachNewData, nFormattedLen, NULL, 
                              nNewValue );
    
    nSuccess = UpdateFieldRaw( poField, iFieldIndex,
                               nStartOffset, nExistingLength, 
                               pachNewData, nFormattedLen );

    free( pachNewData );

    return nSuccess;
}

/************************************************************************/
/*                          SetFloatSubfield()                          */
/************************************************************************/

int ossimDDFRecord::SetFloatSubfield( const char *pszField, int iFieldIndex, 
                                 const char *pszSubfield, int iSubfieldIndex,
                                 double dfNewValue )

{
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    ossimDDFField *poField; 

    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return false;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    ossimDDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return false;

/* -------------------------------------------------------------------- */
/*      How long will the formatted value be?                           */
/* -------------------------------------------------------------------- */
    int nFormattedLen;

    if( !poSFDefn->FormatFloatValue( NULL, 0, &nFormattedLen, dfNewValue ) )
        return false;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nMaxBytes;
    char *pachSubfieldData = (char *) 
        poField->GetSubfieldData(poSFDefn, &nMaxBytes,
                                 iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Add new instance if we have run out of data.                    */
/* -------------------------------------------------------------------- */
    if( nMaxBytes == 0 ||
        (nMaxBytes == 1 && pachSubfieldData[0] == OSSIM_DDF_FIELD_TERMINATOR) )
    {
        CreateDefaultFieldInstance( poField, iSubfieldIndex );

        // Refetch.
        pachSubfieldData = (char *) 
            poField->GetSubfieldData(poSFDefn, &nMaxBytes,
                                     iSubfieldIndex);
    }

/* -------------------------------------------------------------------- */
/*      If the new length matches the existing length, just overlay     */
/*      and return.                                                     */
/* -------------------------------------------------------------------- */
    int nExistingLength;

    poSFDefn->GetDataLength( pachSubfieldData, nMaxBytes, &nExistingLength );

    if( nExistingLength == nFormattedLen )
    {
        return poSFDefn->FormatFloatValue( pachSubfieldData, nFormattedLen,
                                         NULL, dfNewValue );
    }

/* -------------------------------------------------------------------- */
/*      We will need to resize the raw data.                            */
/* -------------------------------------------------------------------- */
    const char *pachFieldInstData;
    int         nInstanceSize, nStartOffset, nSuccess;
    char *pachNewData;

    pachFieldInstData = poField->GetInstanceData( iFieldIndex,
                                                  &nInstanceSize );

    nStartOffset = (int) (pachSubfieldData - pachFieldInstData);

    pachNewData = (char *) malloc(nFormattedLen);
    poSFDefn->FormatFloatValue( pachNewData, nFormattedLen, NULL, 
                              dfNewValue );
    
    nSuccess = UpdateFieldRaw( poField, iFieldIndex,
                               nStartOffset, nExistingLength, 
                               pachNewData, nFormattedLen );

    free( pachNewData );

    return nSuccess;
}