/*
 * PEF: Polar Exchange Format
 *
 * Simple PEF file access routines.
 *
 * Performance depends on the buffered i/o functions of the
 * C-library and the operating system.
 * Assumes random block sequence in PEF file.
 *
 * Created: 5/1996 Martin Hepperle
 */
/*** standard includes ***/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

/*** C does not know what's true and what's false ***/
#define TRUE  1
#define FALSE 0
typedef unsigned int BOOL;

/*** PEF access function ***/
BOOL PEFGetKeyValue ( char * pPEFFileName,
                      char * pBlockName, char * pKeyName,
                      char * pReturnBuffer, int nBufferSize );

/*** internal working routines ***/
static BOOL _PEFLocateBlock ( FILE * fp, char * pBlockName );
static BOOL _PEFGetValue    ( FILE * fp, char * pKeyName,
                              char * pReturnBuffer, int nBufferSize );

/*** sample parse function ***/
void ParsePEF ( char * pFileName );

void main ()
{
   ParsePEF ( "mh62.pef" );
}

void ParsePEF ( char * pFileName )
{
   char szBuffer[80];

   if ( PEFGetKeyValue ( pFileName, "Airfoil", "Description1", szBuffer, sizeof(szBuffer) ) )
     {
      fprintf ( stdout, "Name: %s", szBuffer );

      /* read the number of data sets in this file */
      if ( PEFGetKeyValue ( pFileName, "Airfoil", "NumberSets", szBuffer, sizeof(szBuffer) ) )
        {
         int nSet;
         int nSets = atoi ( szBuffer );

         /* sweep through data sets */
         for ( nSet=0 ; nSet< nSets ; nSet++ )
           {
            char szBlockName[64];
            char szKeyName[64];
            int nPolars;

            fprintf ( stdout, "Set %d\n", nSet+1 );

            /* read the number of polars in this set */
            sprintf ( szBlockName, "Set%d", nSet+1 );
            if ( PEFGetKeyValue ( pFileName, szBlockName, "NumberPolars", szBuffer, sizeof(szBuffer) ) )
              {
               int nPolar;
               int nPolars = atoi ( szBuffer );

               /* sweep through polars of this data set */
               for ( nPolar=0 ; nPolar<nPolars ; nPolar++ )
                 {
                  int nPoint, nPoints;
                  double dReynoldsNumber, dAlfa, dCl, dCd, dCm;
                  fprintf ( stdout, "   Polar %d\n", nPolar+1 );

                  sprintf ( szBlockName, "Set%d-Polar%d", nSet+1, nPolar+1 );
                  /* read the Reynolds number of this polar */
                  if ( PEFGetKeyValue ( pFileName, szBlockName, "ReynoldsNumber", szBuffer, sizeof(szBuffer) ) )
                     dReynoldsNumber = atof ( szBuffer );
                  /* read the number of data points in this polar */
                  if ( PEFGetKeyValue ( pFileName, szBlockName, "NumberPoints", szBuffer, sizeof(szBuffer) ) )
                     nPoints = atoi ( szBuffer );

                  for ( nPoint=0 ; nPoint<nPoints ; nPoint++ )
                    {
                     sprintf ( szKeyName, "Value%02d", nPoint+1 );
                     /* read the current data point */
                     if ( PEFGetKeyValue ( pFileName, szBlockName, szKeyName, szBuffer, sizeof(szBuffer) ) )
                       {
                        sscanf ( szBuffer, "%lf %lf %lf %lf", &dAlfa, &dCl, &dCd, &dCm );
                       }
                    }
                 }
              }
           }
        }
     }
};

BOOL PEFGetKeyValue ( char * pPEFFileName,
                      char * pBlockName, char * pKeyName,
                      char * pReturnBuffer, int nBufferSize )
{
   FILE * fp;
   BOOL bReturn = FALSE;

   if ( fp = fopen ( pPEFFileName, "r" ) )
     {
      if ( _PEFLocateBlock ( fp, pBlockName ) )
        {
         bReturn = _PEFGetValue ( fp, pKeyName, pReturnBuffer, nBufferSize );
        }
      fclose ( fp );
     }
   return ( bReturn );
}

static BOOL _PEFLocateBlock ( FILE * fp, char * pBlockName )
/*
 * Locates the file pointer to the line following pBlockName.
 * Search starts from current position.
 */
{
   char szLine[128];
   int nBlockLength = strlen ( pBlockName );

   while ( fgets ( szLine, sizeof(szLine), fp ) )
     {
      if ( '[' == szLine[0] &&
           0 == strncmp ( szLine+1, pBlockName, nBlockLength ) &&
           ']' == szLine[1+nBlockLength] )
        {
         return ( TRUE );
        }
     }
   return ( FALSE );
}

static BOOL _PEFGetValue ( FILE * fp, char * pKeyName,
                          char * pReturnBuffer, int nBufferSize )
{
   char szLine[128];
   int nKeyLength = strlen ( pKeyName );

   while ( fgets ( szLine, sizeof(szLine), fp ) )
     {
      if ( 0 == strncmp ( szLine, pKeyName, nKeyLength ) &&
           '=' == szLine[nKeyLength] )
        {
         strncpy ( pReturnBuffer, szLine+nKeyLength+1, nBufferSize );
         return ( TRUE );
        }
     }
   return ( FALSE );
}