dbm_embd.c

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/****************************************************************************

  File:           dbm_embd.c

-----------------------------------------------------------------------------
  Created       : A. Beck,  Hilscher GmbH
  Date          : 28-Jul-2001

  Project       : direct access of a DBM for embedded systems

-----------------------------------------------------------------------------

  Description:

      application LIB, containing library routines to handle a DBM file

  Functions:

      short dbm_init           ( void * );

      short dbm_get_num        ( unsigned char *,
                                 unsigned char * );

      short dbm_get_num_of_set ( unsigned char ,
                                 unsigned short * );

      short dbm_fast_read      ( unsigned char  ,
                                 unsigned short ,
                                 unsigned short ,
                                 void           * ,
                                 unsigned short * );


-----------------------------------------------------------------------------

  Todo:

-----------------------------------------------------------------------------

  Changes:

    Name   Date          Version  Description
    -----------------------------------------------------------------------
    Ab     28-Jul-2001    1.000    created

****************************************************************************/



#include <stdio.h>
#include <string.h>

#pragma  pack (1)

#include "dbm_embd.h"



/* counter to hold the found number of table within the DBM file */
static unsigned char bDbmNumOfTables;

/* structure to fill in the current DBM file table sets and entrie counts */
static DBM_FILE_TABLES  atDbm[DBM_TAB_MAX];


/* <ST> =================================================================================

  Function: dbm_init
            fills up the table names of the given DBM file into a
            indexed structure

  ---------------------------------------------------------------------------------------

  Input   : void* ptDbmFile        - pointer to the DBM file at offset 44

  Output  : -

  Return  : DBM_OK                 - init successful
            DBM_DAT_DIR_FULL       - too much entries found

  ================================================================================= <En> */

short dbm_init( void * ptDbmFile )
{


  DBM_DATSTR     * ptDbmDat;
  DBM_SET_0      * ptDbmSet0;
  unsigned short * pusTableEntry;
  unsigned short   usCounterA;
  unsigned short   usCounterB;


  bDbmNumOfTables = 0;
  ptDbmDat      = (DBM_DATSTR *) ptDbmFile;
  ptDbmSet0     = (DBM_SET_0 *)  ptDbmFile;
  pusTableEntry = (unsigned short *) ptDbmFile;

  usCounterA = 0;
  while ( usCounterA < ptDbmDat->akt_dat && bDbmNumOfTables < DBM_TAB_MAX )
  {
    atDbm[bDbmNumOfTables].pvStartAddress = (void *) ptDbmFile;
    usCounterB = pusTableEntry[sizeof ( DBM_DATSTR ) / 2 + 2 * usCounterA] + 6;

    atDbm[bDbmNumOfTables].usSetNumber = usCounterB;
    ptDbmSet0 = (DBM_SET_0 *)&pusTableEntry[pusTableEntry[usCounterB]];
    memcpy ( &atDbm[bDbmNumOfTables].szName, &ptDbmSet0->name, MAX_NAME_LENGTH );

    atDbm[bDbmNumOfTables].usSetEntries = ptDbmSet0->eintraege;
    atDbm[bDbmNumOfTables].usSetCount = ptDbmSet0->akt_eintraege;
    usCounterA = usCounterA + 1;

    bDbmNumOfTables = bDbmNumOfTables + 1;
  }

  if ( bDbmNumOfTables >= DBM_TAB_MAX )
  {
    return ( DBM_DAT_DIR_FULL );
  }
  else
  {
    return ( DBM_OK );
  }
}

/* <ST> =================================================================================

  Function: dbm_get_num
            returns the handle to the given table name


  ---------------------------------------------------------------------------------------

  Input   : unsigned char *pszName  - pointer to the character string of the
                                      table name
            unsigned char *pbHandle - pointer where to place the handle into

  Output  :

  Return  : DBM_OK                  - handle could be got
            DBM_NO_DAT              - table name not found

  ================================================================================= <En> */

short dbm_get_num( unsigned char *pszName,
                   unsigned char *pbHandle )
{
  unsigned char    bIndex;

  *pbHandle = 0;
  while ( *pbHandle < bDbmNumOfTables )
  {
    /* check for the given name if it can be found
       somewhere in the initialized DBM table */

    bIndex = 0;
    while( pszName[bIndex] == atDbm[*pbHandle].szName[bIndex] && atDbm[*pbHandle].szName[bIndex])
    {
      bIndex++;
    }

    if( atDbm[*pbHandle].szName[bIndex] == 0 && pszName[bIndex] == 0 )
    {
      return ( DBM_OK );
    }
    *pbHandle = *pbHandle + 1;
  }

  /* entry not found in the current DBM file, return error */
  return ( (DBM_NO_DAT) );
}

/* <ST> =================================================================================

  Function: dbm_get_num_of_set
            returns the number of data sets of a table


  ---------------------------------------------------------------------------------------

  Input   : unsigned char bHandle           - handle of the table

            unsigned short *pusNumberOfSets - pointer where to place the
                                              the found number into
  Output  :

  Return  : DBM_OK                  - execution successful
            DBM_NO_DAT              - handle parameter not valid

  ================================================================================= <En> */

short dbm_get_num_of_set( unsigned char bHandle,
                          unsigned short * pusNumberOfSets )
{
  if ( bHandle < bDbmNumOfTables )
  {
    *pusNumberOfSets = atDbm[bHandle].usSetCount;
    return ( 0 );
  }
  else
  {
    *pusNumberOfSets = 0;
    return ( DBM_NO_DAT );
  }
}

/* <ST> =================================================================================

  Function: dbm_get_num_of_set
            returns the number of data sets of a table


  ---------------------------------------------------------------------------------------

  Input   : unsigned char  bHandle               - handle of the table
            unsigned short usSetNumber           - set number starting with 1
            unsigned short usMaximumLength       - the maximum reserved buffer
                                                   length where the data set
                                                   shall be copied to
            void           *pvDestinationPointer - pointer to the destination
                                                   buffer
            unsigned short *pusRealLength        - pointer to the real length
                                                   variable, where the function
                                                   places the real length of
                                                   the read data set

  Output  :

  Return  : DBM_OK                   - execution successful
            DBM_NO_DAT               - handle parameter not valid
            DBM_NO_SET               - usSetNumber out of range
            DBM_SET_DEL              - data set is not available
            DBM_NOT_ENOUGH_FREESPACE - usMaximumLength indicated to less
                                       freespace for the data set

  ================================================================================= <En> */


short dbm_fast_read ( unsigned char  bHandle,
                      unsigned short usSetNumber,
                      unsigned short usMaximumLength,
                      void           * pvDestinationPointer,
                      unsigned short * pusRealLength )
{
  unsigned short * pusTableEntry;
  DBM_SET  * pvSetEntry;


  *pusRealLength = 0;
  if ( bHandle < bDbmNumOfTables )
  {
    if ( usSetNumber <= atDbm[bHandle].usSetEntries )
    {
      pusTableEntry = atDbm[bHandle].pvStartAddress;

      if ( pusTableEntry[atDbm[bHandle].usSetNumber + usSetNumber]  )
      {
        pvSetEntry = (DBM_SET *)&pusTableEntry[pusTableEntry[atDbm[bHandle].usSetNumber + usSetNumber]];

        *pusRealLength = pvSetEntry->usmax - 12;
        if ( pvSetEntry->bUngerade & 0x01 )
        {
          *pusRealLength = *pusRealLength - 1;
        }

        if ( *pusRealLength <= usMaximumLength )
        {
          memcpy ( pvDestinationPointer, &pvSetEntry->ausData[0], *pusRealLength );
          return ( 0 );
        }
        else
        {
          *pusRealLength = 0;
          return ( DBM_NOT_ENOUGH_FREESPACE );
        }
      }
      else
      {
        return ( DBM_SET_DEL );
      }
    }
    else
    {
      return ( DBM_NO_SET );
    }
  }
  else
  {
    return ( DBM_NO_DAT );
  }
}