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

             FUNCTION READSURFACES

  READSURFACES READS VARIABLES ON DENSITY SURFACES FROM FILE

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

readsurfaces_(

 int *denseparms,         /* NUMBER OF STORED DENSITY SURFACE
                             VARIABLES, INCLUDING PRESSURE ON SURFACE */

 int *jj,                 /* SEQUENTIAL STATION NUMBER */

 int *startpoint,         /* PRESENT POSITION FILE POSITION */

 int *fposfile,           /* POSITION FILE ID NUMBER */

 int *ireqpars,           /* NUMBER OF REQUESTED VARIABLES */

 int *ip2,                /* VARIABLE CODES */

 int *denserecord,        /* DESIRED FILE POSITON FOR VARIABLES */

 int *olddenserecord,     /* PRESENT FILE POSITION FOR VARIABLES */

 int *ioutfile,           /* FILE IDS FOR VARIABLE FILES */
 
 int *npot,               /* SEQUENTIAL ORDER FOR PRESENT REFERENCE
                             LEVEL */

 int *maxpot,             /* MAXIMUM NUMBER OF REFERENCE LEVELS */

 float *densevar,         /* VARIABLES ON DENSITY SURFACES */

 int *maxsurf,            /* MAXIMUM NUMBER OF DENSITY SURFACES */

 int *maxparm,            /* MAXIMUM NUMBER OF VARIABLES */

 int *maxcal,             /* MAXIMUM NUMBER OF MEASURED/CALCULATED
                             VARIABLES */

 int *jp,                 /* PROBE CODE */

 int *nprec,              /* RECORD POSITION FOR EACH VARIABLE */

 int *ishallow,           /* INDEX OF FIRST DENSITY SURFACE RECORD */

 int *ideep,              /* INDEX OF LAST DENSITY SURFACE RECORD */

 int *numdense,           /* TOTAL POSSIBLE DENSITY SURFACES */

 float *missing,          /* MISSING VALUE MARKER */

 float *tooshallow,       /* MARKER FOR DENSITY SURFACE TOO SHALLOW */

 float *toodeep,          /* MARKER FOR DENSITY SURFACE TOO DEEP */

 int *ieof                /* END OF FILE MARKER */

              )

{

 int i,i0,i2,j,ivarfile,ivarpos,nlevels=0;
 float submissing, submissing2;
 long int size;

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

 COMPUTE RECORD SIZE (NUMBER OF DENSITY SURFACE VARIABLES)
 DENSEPARMS INCLUDES PRESSURE ON DENSITY SURFACE VARIABLE

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

 size = (*denseparms +2) * sizeof(int);

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

 POSITION POSITIONS FILE

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

 fseek( fp[*fposfile],( *jj - *startpoint ) * size , SEEK_CUR );

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

 ADJUST PRESENT POSITIONS FILE PROFILE NUMBER (ADD ONE)

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

 *startpoint = *jj + 1;

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

 WRITE OUT NUMBER OF DENSITY SURFACES WITH VALUES AND FIRST
 SURFACE WITH VALUE

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

 fread( &nlevels, sizeof(int), 1, fp[*fposfile]);
 fread( ishallow, sizeof(int), 1, fp[*fposfile]);
 if ( *ishallow > 0 ) *ideep= (*ishallow + nlevels) -1;
 else *ideep=0;

 if ( feof(fp[*fposfile]) ) {
  *ieof = 1;
  return;
 }

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

 READ POSITIONS FOR EACH VARIABLE FROM POSITIONS FILE

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

 fread( (denserecord+1), sizeof(int), *denseparms, fp[*fposfile]);

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

 START LOOP TO READ IN VARIABLES
 A -1 IN DENSERECORD MEANS NO DATA FOR VARIABLE

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

 for ( i0=1; i0<= *ireqpars; i0++) {

  i = *(ip2+i0);
  i2 = *( nprec + (((*jp)-1) * *maxcal) + (i-1));

  printf("i2 %d %d %d\n",i,i2, *(denserecord + i2));
  if ( *(denserecord + i2) > -1 ) {

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

 GO TO DESIGNATED POSITION IN VARIABLE FILE

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

   ivarfile= *(ioutfile+((*npot-1) * (*maxparm + 1)) + i);

   fseek( fp[ivarfile],
    (*(denserecord+i2) - *(olddenserecord+i2)) * sizeof(float),
    SEEK_CUR);

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

 READ VARIABLE DATA INTO ARRAY

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

   ivarpos= ((i-1) * *maxsurf) + (*ishallow-1);
   fread( (densevar + ivarpos), sizeof(float), nlevels,fp[ivarfile]);

   *(olddenserecord+i2) = *(denserecord+i2)+ nlevels;
   *(denserecord+i2) = *(olddenserecord+i2);

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

 ENTER MISSING VALUES INTO NONUSED DENSITY SURFACES

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

  submissing= *missing;
  submissing2= *missing;
  if ( *(densevar + ivarpos) > *toodeep &&
   *(densevar + ivarpos) <= *tooshallow+1. )
     submissing= *tooshallow;
  if ( *(densevar + ivarpos + (nlevels-1)) <= *toodeep +1. &&
       *(densevar + ivarpos + (nlevels-1)) > *missing )
   submissing2= *toodeep;

  ivarpos -= (*ishallow-1);

   for ( j = ivarpos; j < ivarpos + (*ishallow-1); j++ ) 
    *(densevar + j) = submissing; 

   ivarpos += (*ideep-1);
   for ( j = ivarpos+1; j < ivarpos + *numdense; j++)
    *(densevar + j) = submissing2;

  }

 }

}