stream_cdf_i.c

#if defined (HAVE_CONFIG_H)
#include "config.h"
#endif

#ifdef HAVE_LIBNETCDF

//#define TEST_GROUPS 1

#include <ctype.h>

#include "dmemory.h"
#include "gaussgrid.h"
#include "cdi_int.h"
#include "cdi_uuid.h"
#include "stream_cdf.h"
#include "cdf_int.h"
#include "varscan.h"
#include "vlist.h"
#include "cdf_util.h"
#include "cdf_lazy_grid.h"

#undef  UNDEFID
#define UNDEFID  CDI_UNDEFID

#define  X_AXIS  1
#define  Y_AXIS  2
#define  Z_AXIS  3
#define  T_AXIS  4

#define  POSITIVE_UP    1
#define  POSITIVE_DOWN  2

typedef struct {
  int     ncvarid;
  int     dimtype;
  size_t  len;
  char    name[CDI_MAX_NAME];
}
ncdim_t;
#define  MAX_COORDVARS  4
#define  MAX_AUXVARS    4

typedef struct {
  int      ncid;
  int      isvar;
  bool     ignore;
  bool     islon;
  bool     islat;
  bool     islev;
  bool     istime;
  bool     warn;
  bool     climatology;
  bool     lformula;
  bool     lformulaterms;
  int      tsteptype;
  int      param;
  int      code;
  int      tabnum;
  int      bounds;
  int      gridID;
  int      zaxisID;
  int      gridtype;
  int      zaxistype;
  int      xdim;
  int      ydim;
  int      zdim;
  int      xvarid;
  int      yvarid;
  int      zvarid;
  int      tvarid;
  int      psvarid;
  int      p0varid;
  int      ncoordvars;
  int      coordvarids[MAX_COORDVARS];
  int      nauxvars;
  int      auxvarids[MAX_AUXVARS];
  int      cellarea;
  int      calendar;
  int      tableID;
  int      truncation;
  int      position;
  bool     defmissval;
  bool     deffillval;
  int      xtype;
  int      ndims;
  int      gmapid;
  int      positive;
  int      dimids[8];
  int      dimtype[8];
  int      chunks[8];
  int      chunked;
  int      chunktype;
  int      natts;
  int      deflate;
  bool     lunsigned;
  bool     lvalidrange;
  int     *atts;
  size_t   vctsize;
  double  *vct;
  double   missval;
  double   fillval;
  double   addoffset;
  double   scalefactor;
  double   validrange[2];
  char     name[CDI_MAX_NAME];
  char     longname[CDI_MAX_NAME];
  char     stdname[CDI_MAX_NAME];
  char     units[CDI_MAX_NAME];
  char     extra[CDI_MAX_NAME];
  ensinfo_t   *ensdata;    /* Ensemble information */
}
ncvar_t;


static
void scanTimeString(const char *ptu, int *rdate, int *rtime)
{
  int year = 1, month = 1, day = 1;
  int hour = 0, minute = 0, second = 0;
  int v1 = 1, v2 = 1, v3 = 1;

  *rdate = 0;
  *rtime = 0;

  if ( *ptu )
    {
      v1 = atoi(ptu);
      if ( v1 < 0 ) ptu++;
      while ( isdigit((int) *ptu) ) ptu++;
      if ( *ptu )
        {
          v2 = atoi(++ptu);
          while ( isdigit((int) *ptu) ) ptu++;
          if ( *ptu )
            {
              v3 = atoi(++ptu);
              while ( isdigit((int) *ptu) ) ptu++;
            }
        }
    }

  if ( v3 > 999 && v1 < 32 )
    { year = v3; month = v2; day = v1; }
  else
    { year = v1; month = v2; day = v3; }

  while ( isspace((int) *ptu) ) ptu++;

  if ( *ptu )
    {
      while ( ! isdigit((int) *ptu) ) ptu++;

      hour = atoi(ptu);
      while ( isdigit((int) *ptu) ) ptu++;
      if ( *ptu == ':' )
        {
          ptu++;
          minute = atoi(ptu);
          while ( isdigit((int) *ptu) ) ptu++;
          if ( *ptu == ':' )
            {
              ptu++;
              second = atoi(ptu);
            }
        }
    }

  *rdate = cdiEncodeDate(year, month, day);
  *rtime = cdiEncodeTime(hour, minute, second);
}

static
int scanTimeUnit(const char *unitstr)
{
  size_t len = strlen(unitstr);
  int timeunit = get_timeunit(len, unitstr);
  if ( timeunit == -1 )
    Message("Unsupported TIMEUNIT: %s!", unitstr);

  return timeunit;
}

static
void setForecastTime(const char *timestr, taxis_t *taxis)
{
  (*taxis).fdate = 0;
  (*taxis).ftime = 0;

  int len = (int) strlen(timestr);
  if ( len == 0 ) return;

  int fdate = 0, ftime = 0;
  scanTimeString(timestr, &fdate, &ftime);

  (*taxis).fdate = fdate;
  (*taxis).ftime = ftime;
}

static
int setBaseTime(const char *timeunits, taxis_t *taxis)
{
  int timetype = TAXIS_ABSOLUTE;
  int rdate = -1, rtime = -1;

  size_t len = strlen(timeunits);
  char *tu = (char *) Malloc((len+1) * sizeof (char));
  memcpy(tu, timeunits, (len+1) * sizeof (char));
  char *ptu = tu;

  for ( size_t i = 0; i < len; i++ ) ptu[i] = (char)tolower((int) ptu[i]);

  int timeunit = get_timeunit(len, ptu);
  if ( timeunit == -1 )
    {
      Message("Unsupported TIMEUNIT: %s!", timeunits);
      return 1;
    }

  while ( ! isspace(*ptu) && *ptu != 0 ) ptu++;
  if ( *ptu )
    {
      while ( isspace(*ptu) ) ptu++;

      if ( memcmp(ptu, "as", 2) == 0 )
        timetype = TAXIS_ABSOLUTE;
      else if ( memcmp(ptu, "since", 5) == 0 )
        timetype = TAXIS_RELATIVE;

      while ( ! isspace(*ptu) && *ptu != 0 ) ptu++;
      if ( *ptu )
        {
          while ( isspace(*ptu) ) ptu++;

          if ( timetype == TAXIS_ABSOLUTE )
            {
              if ( memcmp(ptu, "%y%m%d.%f", 9) != 0 && timeunit == TUNIT_DAY )
                {
                  Message("Unsupported format %s for TIMEUNIT day!", ptu);
                  timeunit = -1;
                }
              else if ( memcmp(ptu, "%y%m.%f", 7) != 0 && timeunit == TUNIT_MONTH )
                {
                  Message("Unsupported format %s for TIMEUNIT month!", ptu);
                  timeunit = -1;
                }
            }
          else if ( timetype == TAXIS_RELATIVE )
            {
              scanTimeString(ptu, &rdate, &rtime);

              (*taxis).rdate = rdate;
              (*taxis).rtime = rtime;

              if ( CDI_Debug )
                Message("rdate = %d  rtime = %d", rdate, rtime);
            }
        }
    }

  (*taxis).type = timetype;
  (*taxis).unit = timeunit;

  Free(tu);

  if ( CDI_Debug )
    Message("timetype = %d  unit = %d", timetype, timeunit);

  return 0;
}

static
void cdfGetAttInt(int fileID, int ncvarid, const char *attname, int attlen, int *attint)
{
  nc_type atttype;
  size_t nc_attlen;

  *attint = 0;

  cdf_inq_atttype(fileID, ncvarid, attname, &atttype);
  cdf_inq_attlen(fileID, ncvarid, attname, &nc_attlen);

  if ( atttype != NC_CHAR )
    {
      int *pintatt = (int)nc_attlen > attlen
        ? (int *)(Malloc(nc_attlen * sizeof (int))) : attint;

      cdf_get_att_int(fileID, ncvarid, attname, pintatt);

      if ( (int)nc_attlen > attlen )
        {
          memcpy(attint, pintatt, (size_t)attlen * sizeof (int));
          Free(pintatt);
        }
    }
}

static
void cdfGetAttDouble(int fileID, int ncvarid, char *attname, int attlen, double *attdouble)
{
  nc_type atttype;
  size_t nc_attlen;

  *attdouble = 0;

  cdf_inq_atttype(fileID, ncvarid, attname, &atttype);
  cdf_inq_attlen(fileID, ncvarid, attname, &nc_attlen);

  if ( atttype != NC_CHAR )
    {
      double *pdoubleatt = NULL;

      if ( (int)nc_attlen > attlen )
        pdoubleatt = (double *) Malloc(nc_attlen * sizeof (double));
      else
        pdoubleatt = attdouble;

      cdf_get_att_double(fileID, ncvarid, attname, pdoubleatt);

      if ( (int)nc_attlen > attlen )
        {
          memcpy(attdouble, pdoubleatt, (size_t)attlen * sizeof (double));
          Free(pdoubleatt);
        }
    }
}

static
bool cdfCheckAttText(int fileID, int ncvarid, const char *attname)
{
  bool status = false;
  nc_type atttype;

  int status_nc = nc_inq_atttype(fileID, ncvarid, attname, &atttype);

  if ( status_nc == NC_NOERR
       && (atttype == NC_CHAR
#if  defined  (HAVE_NETCDF4)
           || atttype == NC_STRING
#endif
           ) )
    {
      status = true;
    }

  return status;
}

static
void cdfGetAttText(int fileID, int ncvarid, const char *attname, int attlen, char *atttext)
{
  nc_type atttype;
  size_t nc_attlen;

  cdf_inq_atttype(fileID, ncvarid, attname, &atttype);
  cdf_inq_attlen(fileID, ncvarid, attname, &nc_attlen);

  if ( atttype == NC_CHAR )
    {
      char attbuf[65636];
      if ( nc_attlen < sizeof(attbuf) )
        {
          cdf_get_att_text(fileID, ncvarid, attname, attbuf);

          if ( (int) nc_attlen > (attlen-1) ) nc_attlen = (size_t)(attlen-1);

          attbuf[nc_attlen++] = 0;
          memcpy(atttext, attbuf, nc_attlen);
        }
      else
        {
          atttext[0] = 0;
        }
    }
#if  defined  (HAVE_NETCDF4)
  else if ( atttype == NC_STRING )
    {
      if ( nc_attlen == 1 )
        {
          char *attbuf = NULL;
          cdf_get_att_string(fileID, ncvarid, attname, &attbuf);

          size_t ssize = strlen(attbuf) + 1;

          if ( ssize > (size_t)attlen ) ssize = (size_t)attlen;
          memcpy(atttext, attbuf, ssize);
          atttext[ssize - 1] = 0;
          Free(attbuf);
        }
      else
        {
          atttext[0] = 0;
        }
    }
#endif
}

static
bool xtypeIsText(nc_type xtype)
{
  bool isText = false;

  if      ( xtype == NC_CHAR ) isText = true;
#if  defined  (HAVE_NETCDF4)
  else if ( xtype == NC_STRING ) isText = true;
#endif

  return isText;
}

static
bool xtypeIsFloat(nc_type xtype)
{
  bool isFloat = xtype == NC_FLOAT || xtype == NC_DOUBLE;

  return isFloat;
}

static
bool xtypeIsInt(nc_type xtype)
{
  bool isInt = xtype == NC_SHORT || xtype == NC_INT
            || xtype == NC_BYTE
#if  defined  (HAVE_NETCDF4)
            || xtype == NC_USHORT || xtype == NC_UINT
            || xtype == NC_UBYTE
#endif
             ;

  return isInt;
}

static
int cdfInqDatatype(int xtype, bool lunsigned)
{
  int datatype = -1;

#if  defined  (HAVE_NETCDF4)
  if ( xtype == NC_BYTE && lunsigned ) xtype = NC_UBYTE;
#endif

  if      ( xtype == NC_BYTE   )  datatype = DATATYPE_INT8;
  /* else if ( xtype == NC_CHAR   )  datatype = DATATYPE_UINT8; */
  else if ( xtype == NC_SHORT  )  datatype = DATATYPE_INT16;
  else if ( xtype == NC_INT    )  datatype = DATATYPE_INT32;
  else if ( xtype == NC_FLOAT  )  datatype = DATATYPE_FLT32;
  else if ( xtype == NC_DOUBLE )  datatype = DATATYPE_FLT64;
#if  defined  (HAVE_NETCDF4)
  else if ( xtype == NC_UBYTE  )  datatype = DATATYPE_UINT8;
  else if ( xtype == NC_LONG   )  datatype = DATATYPE_INT32;
  else if ( xtype == NC_USHORT )  datatype = DATATYPE_UINT16;
  else if ( xtype == NC_UINT   )  datatype = DATATYPE_UINT32;
  else if ( xtype == NC_INT64  )  datatype = DATATYPE_FLT64;
  else if ( xtype == NC_UINT64 )  datatype = DATATYPE_FLT64;
#endif

  return datatype;
}


/* not used
int cdfInqRecord(stream_t *streamptr, int *varID, int *levelID)
{
  int tsID, recID;

  recID = streamptr->tsteps[0].curRecID++;
  printf("cdfInqRecord recID %d %d\n", recID, streamptr->tsteps[0].curRecID);
  printf("cdfInqRecord tsID %d\n", streamptr->curTsID);

  if ( streamptr->tsteps[0].curRecID >= streamptr->tsteps[0].nrecs )
    {
      streamptr->tsteps[0].curRecID = 0;
    }

  *varID   = streamptr->tsteps[0].records[recID].varID;
  *levelID = streamptr->tsteps[0].records[recID].levelID;

  streamptr->record->varID   = *varID;
  streamptr->record->levelID = *levelID;

  if ( CDI_Debug )
    Message("recID = %d  varID = %d  levelID = %d", recID, *varID, *levelID);

  return (recID+1);
}
*/

void cdf_scale_add(size_t size, double *data, double addoffset, double scalefactor)
{
  int laddoffset   = IS_NOT_EQUAL(addoffset, 0);
  int lscalefactor = IS_NOT_EQUAL(scalefactor, 1);

  if ( laddoffset || lscalefactor )
    {
      for ( size_t i = 0; i < size; ++i )
        {
          if ( lscalefactor ) data[i] *= scalefactor;
          if ( laddoffset )   data[i] += addoffset;
        }
    }
}

static
void cdfCreateRecords(stream_t *streamptr, int tsID)
{
  if ( tsID < 0 || (tsID >= streamptr->ntsteps && tsID > 0) ) return;

  if ( streamptr->tsteps[tsID].nallrecs > 0 ) return;

  int vlistID  = streamptr->vlistID;

  tsteps_t* sourceTstep = streamptr->tsteps;
  tsteps_t* destTstep = sourceTstep + tsID;

  int nvars = vlistNvars(vlistID);
  int nrecs = vlistNrecs(vlistID);

  if ( nrecs <= 0 ) return;

  if ( tsID == 0 )
    {
      int nvrecs = nrecs; /* use all records at first timestep */

      streamptr->nrecs += nrecs;

      destTstep->records    = (record_t *) Malloc((size_t)nrecs*sizeof(record_t));
      destTstep->nrecs      = nrecs;
      destTstep->nallrecs   = nrecs;
      destTstep->recordSize = nrecs;
      destTstep->curRecID   = UNDEFID;
      destTstep->recIDs     = (int *) Malloc((size_t)nvrecs*sizeof (int));;
      for ( int recID = 0; recID < nvrecs; recID++ ) destTstep->recIDs[recID] = recID;

      record_t *records = destTstep->records;

      for ( int varID = 0, recID = 0; varID < nvars; varID++ )
        {
          int zaxisID = vlistInqVarZaxis(vlistID, varID);
          int nlev    = zaxisInqSize(zaxisID);
          for ( int levelID = 0; levelID < nlev; levelID++ )
            {
              recordInitEntry(&records[recID]);
              records[recID].varID   = (short)varID;
              records[recID].levelID = (short)levelID;
              recID++;
            }
        }
    }
  else if ( tsID == 1 )
    {
      int nvrecs = 0;
      for ( int varID = 0; varID < nvars; varID++ )
        {
          if ( vlistInqVarTsteptype(vlistID, varID) != TSTEP_CONSTANT )
            {
              int zaxisID = vlistInqVarZaxis(vlistID, varID);
              nvrecs += zaxisInqSize(zaxisID);
            }
        }

      streamptr->nrecs += nvrecs;

      destTstep->records    = (record_t *) Malloc((size_t)nrecs*sizeof(record_t));
      destTstep->nrecs      = nvrecs;
      destTstep->nallrecs   = nrecs;
      destTstep->recordSize = nrecs;
      destTstep->curRecID   = UNDEFID;

      memcpy(destTstep->records, sourceTstep->records, (size_t)nrecs*sizeof(record_t));

      if ( nvrecs )
        {
          destTstep->recIDs = (int *) Malloc((size_t)nvrecs * sizeof (int));
          for ( int recID = 0, vrecID = 0; recID < nrecs; recID++ )
            {
              int varID = destTstep->records[recID].varID;
              if ( vlistInqVarTsteptype(vlistID, varID) != TSTEP_CONSTANT )
                {
                  destTstep->recIDs[vrecID++] = recID;
                }
            }
        }
    }
  else
    {
      if ( streamptr->tsteps[1].records == 0 ) cdfCreateRecords(streamptr, 1);

      int nvrecs = streamptr->tsteps[1].nrecs;

      streamptr->nrecs += nvrecs;

      destTstep->records    = (record_t *) Malloc((size_t)nrecs*sizeof(record_t));
      destTstep->nrecs      = nvrecs;
      destTstep->nallrecs   = nrecs;
      destTstep->recordSize = nrecs;
      destTstep->curRecID   = UNDEFID;

      memcpy(destTstep->records, sourceTstep->records, (size_t)nrecs*sizeof(record_t));

      destTstep->recIDs     = (int *) Malloc((size_t)nvrecs * sizeof(int));

      memcpy(destTstep->recIDs, streamptr->tsteps[1].recIDs, (size_t)nvrecs*sizeof(int));
    }
}

static
int cdf_time_dimid(int fileID, int ndims, int nvars)
{
  char dimname[80];
  for ( int dimid = 0; dimid < ndims; ++dimid )
    {
      dimname[0] = 0;
      cdf_inq_dimname(fileID, dimid, dimname);
      size_t len = strlen(dimname);
      if ( len >= 4 && memcmp(dimname, "time", 4) == 0 ) return dimid;
      if ( len >= 4 && memcmp(dimname, "Time", 4) == 0 ) return dimid;
    }

  for ( int varid = 0; varid < nvars; ++varid )
    {
      nc_type xtype;
      int nvdims, nvatts, dimids[9];
      cdf_inq_var(fileID, varid, NULL, &xtype, &nvdims, dimids, &nvatts);
      if ( nvdims == 1 )
        {
          char sbuf[CDI_MAX_NAME];
          for ( int iatt = 0; iatt < nvatts; ++iatt )
            {
              sbuf[0] = 0;
              cdf_inq_attname(fileID, varid, iatt, sbuf);
              if ( strncmp(sbuf, "units", 5) == 0 )
                {
                  cdfGetAttText(fileID, varid, "units", sizeof(sbuf), sbuf);
                  str_tolower(sbuf);

                  if ( is_time_units(sbuf) ) return dimids[0];
                }
            }
        }
    }

  return UNDEFID;
}

static
void init_ncdims(long ndims, ncdim_t *ncdims)
{
  for ( long ncdimid = 0; ncdimid < ndims; ncdimid++ )
    {
      ncdims[ncdimid].ncvarid      = UNDEFID;
      ncdims[ncdimid].dimtype      = UNDEFID;
      ncdims[ncdimid].len          = 0;
      ncdims[ncdimid].name[0]      = 0;
    }
}

static
void init_ncvars(long nvars, ncvar_t *ncvars)
{
  for ( long ncvarid = 0; ncvarid < nvars; ++ncvarid )
    {
      ncvars[ncvarid].ncid            = UNDEFID;
      ncvars[ncvarid].isvar           = UNDEFID;
      ncvars[ncvarid].ignore          = false;
      ncvars[ncvarid].islon           = false;
      ncvars[ncvarid].islat           = false;
      ncvars[ncvarid].islev           = false;
      ncvars[ncvarid].istime          = false;
      ncvars[ncvarid].warn            = false;
      ncvars[ncvarid].climatology     = false;
      ncvars[ncvarid].lformula        = false;
      ncvars[ncvarid].lformulaterms   = false;
      ncvars[ncvarid].tsteptype       = TSTEP_CONSTANT;
      ncvars[ncvarid].param           = UNDEFID;
      ncvars[ncvarid].code            = UNDEFID;
      ncvars[ncvarid].tabnum          = 0;
      ncvars[ncvarid].calendar        = FALSE;
      ncvars[ncvarid].bounds          = UNDEFID;
      ncvars[ncvarid].gridID          = UNDEFID;
      ncvars[ncvarid].zaxisID         = UNDEFID;
      ncvars[ncvarid].gridtype        = UNDEFID;
      ncvars[ncvarid].zaxistype       = UNDEFID;
      ncvars[ncvarid].xdim            = UNDEFID;
      ncvars[ncvarid].ydim            = UNDEFID;
      ncvars[ncvarid].zdim            = UNDEFID;
      ncvars[ncvarid].xvarid          = UNDEFID;
      ncvars[ncvarid].yvarid          = UNDEFID;
      ncvars[ncvarid].zvarid          = UNDEFID;
      ncvars[ncvarid].tvarid          = UNDEFID;
      ncvars[ncvarid].psvarid         = UNDEFID;
      ncvars[ncvarid].p0varid         = UNDEFID;
      ncvars[ncvarid].ncoordvars      = 0;
      for ( int i = 0; i < MAX_COORDVARS; ++i )
        ncvars[ncvarid].coordvarids[i]  = UNDEFID;
      ncvars[ncvarid].nauxvars      = 0;
      for ( int i = 0; i < MAX_AUXVARS; ++i )
        ncvars[ncvarid].auxvarids[i]  = UNDEFID;
      ncvars[ncvarid].cellarea        = UNDEFID;
      ncvars[ncvarid].tableID         = UNDEFID;
      ncvars[ncvarid].xtype           = 0;
      ncvars[ncvarid].ndims           = 0;
      ncvars[ncvarid].gmapid          = UNDEFID;
      ncvars[ncvarid].vctsize         = 0;
      ncvars[ncvarid].vct             = NULL;
      ncvars[ncvarid].truncation      = 0;
      ncvars[ncvarid].position        = 0;
      ncvars[ncvarid].positive        = 0;
      ncvars[ncvarid].chunked         = 0;
      ncvars[ncvarid].chunktype       = UNDEFID;
      ncvars[ncvarid].defmissval      = false;
      ncvars[ncvarid].deffillval      = false;
      ncvars[ncvarid].missval         = 0;
      ncvars[ncvarid].fillval         = 0;
      ncvars[ncvarid].addoffset       = 0;
      ncvars[ncvarid].scalefactor     = 1;
      ncvars[ncvarid].name[0]         = 0;
      ncvars[ncvarid].longname[0]     = 0;
      ncvars[ncvarid].stdname[0]      = 0;
      ncvars[ncvarid].units[0]        = 0;
      ncvars[ncvarid].extra[0]        = 0;
      ncvars[ncvarid].natts           = 0;
      ncvars[ncvarid].atts            = NULL;
      ncvars[ncvarid].deflate         = 0;
      ncvars[ncvarid].lunsigned       = false;
      ncvars[ncvarid].lvalidrange     = false;
      ncvars[ncvarid].validrange[0]   = VALIDMISS;
      ncvars[ncvarid].validrange[1]   = VALIDMISS;
      ncvars[ncvarid].ensdata         = NULL;
    }
}

static
void cdf_set_var(ncvar_t *ncvars, int ncvarid, short isvar)
{
  if ( ncvars[ncvarid].isvar != UNDEFID &&
       ncvars[ncvarid].isvar != isvar   &&
       ncvars[ncvarid].warn  == false )
    {
      if ( ! ncvars[ncvarid].ignore )
        Warning("Inconsistent variable definition for %s!", ncvars[ncvarid].name);

      ncvars[ncvarid].warn = true;
      isvar = FALSE;
    }

  ncvars[ncvarid].isvar = isvar;
}

static
void cdf_set_dim(ncvar_t *ncvars, int ncvarid, int dimid, int dimtype)
{
  if ( ncvars[ncvarid].dimtype[dimid] != UNDEFID &&
       ncvars[ncvarid].dimtype[dimid] != dimtype )
    {
      Warning("Inconsistent dimension definition for %s! dimid = %d;  type = %d;  newtype = %d",
              ncvars[ncvarid].name, dimid, ncvars[ncvarid].dimtype[dimid], dimtype);
    }

  ncvars[ncvarid].dimtype[dimid] = dimtype;
}

static
int scan_hybrid_formula(int ncid, int ncfvarid, int *apvarid, int *bvarid, int *psvarid, int *avarid, int *p0varid)
{
  int status = 0;
  *apvarid = -1;
  *bvarid  = -1;
  *psvarid = -1;
  *avarid  = -1;
  *p0varid = -1;
  enum { attstringlen = 8192 }; char attstring[attstringlen];
  cdfGetAttText(ncid, ncfvarid, "formula", attstringlen, attstring);
  if ( strcmp(attstring, "p = ap + b*ps") == 0 )
    {
      status = 1;
      bool lstop = false;
      int dimvarid;
      cdfGetAttText(ncid, ncfvarid, "formula_terms", attstringlen, attstring);
      char *pstring = attstring;

      for ( int i = 0; i < 3; i++ )
        {
          while ( isspace((int) *pstring) ) pstring++;
          if ( *pstring == 0 ) break;
          char *tagname = pstring;
          while ( !isspace((int) *pstring) && *pstring != 0 ) pstring++;
          if ( *pstring == 0 ) lstop = true;
          *pstring++ = 0;

          while ( isspace((int) *pstring) ) pstring++;
          if ( *pstring == 0 ) break;
          char *varname = pstring;
          while ( !isspace((int) *pstring) && *pstring != 0 ) pstring++;
          if ( *pstring == 0 ) lstop = true;
          *pstring++ = 0;

          int status_nc = nc_inq_varid(ncid, varname, &dimvarid);
          if ( status_nc == NC_NOERR )
            {
              if      ( strcmp(tagname, "ap:") == 0 ) *apvarid = dimvarid;
              else if ( strcmp(tagname, "b:")  == 0 ) *bvarid  = dimvarid;
              else if ( strcmp(tagname, "ps:") == 0 ) *psvarid = dimvarid;
            }
          else if ( strcmp(tagname, "ps:") != 0 )
            {
              Warning("%s - %s", nc_strerror(status_nc), varname);
            }

          if ( lstop ) break;
        }
    }
  else if ( strcmp(attstring, "xxxp = a*p0 + b*ps") == 0 )
    {
      status = 2;
      bool lstop = false;
      int dimvarid;
      cdfGetAttText(ncid, ncfvarid, "formula_terms", attstringlen, attstring);
      char *pstring = attstring;

      for ( int i = 0; i < 4; i++ )
        {
          while ( isspace((int) *pstring) ) pstring++;
          if ( *pstring == 0 ) break;
          char *tagname = pstring;
          while ( !isspace((int) *pstring) && *pstring != 0 ) pstring++;
          if ( *pstring == 0 ) lstop = true;
          *pstring++ = 0;

          while ( isspace((int) *pstring) ) pstring++;
          if ( *pstring == 0 ) break;
          char *varname = pstring;
          while ( !isspace((int) *pstring) && *pstring != 0 ) pstring++;
          if ( *pstring == 0 ) lstop = true;
          *pstring++ = 0;

          int status_nc = nc_inq_varid(ncid, varname, &dimvarid);
          if ( status_nc == NC_NOERR )
            {
              if      ( strcmp(tagname, "a:")  == 0 ) *avarid  = dimvarid;
              else if ( strcmp(tagname, "b:")  == 0 ) *bvarid  = dimvarid;
              else if ( strcmp(tagname, "ps:") == 0 ) *psvarid = dimvarid;
              else if ( strcmp(tagname, "p0:") == 0 ) *p0varid = dimvarid;
            }
          else if ( strcmp(tagname, "ps:") != 0 )
            {
              Warning("%s - %s", nc_strerror(status_nc), varname);
            }

          if ( lstop ) break;
        }
    }

  return status;
}

static
bool isHybridSigmaPressureCoordinate(int ncid, int ncvarid, ncvar_t *ncvars, const ncdim_t *ncdims)
{
  bool status = false;
  int ncfvarid = ncvarid;
  ncvar_t *ncvar = &ncvars[ncvarid];

  if ( strcmp(ncvar->stdname, "atmosphere_hybrid_sigma_pressure_coordinate") == 0 )
    {
      cdiConvention = CDI_CONVENTION_CF;

      status = true;
      ncvar->zaxistype = ZAXIS_HYBRID;
      int dimid = ncvar->dimids[0];
      size_t dimlen = ncdims[dimid].len;

      int ret;
      int apvarid1 = -1, bvarid1 = -1, psvarid1 = -1, avarid1 = -1, p0varid1 = -1;
      if ( ncvars[ncfvarid].lformula && ncvars[ncfvarid].lformulaterms )
        ret = scan_hybrid_formula(ncid, ncfvarid, &apvarid1, &bvarid1, &psvarid1, &avarid1, &p0varid1);
      if ( apvarid1 != -1 ) ncvars[apvarid1].isvar = FALSE;
      if ( bvarid1  != -1 ) ncvars[bvarid1].isvar  = FALSE;
      if ( psvarid1 != -1 ) ncvar->psvarid = psvarid1;
      if ( avarid1  != -1 ) ncvars[avarid1].isvar = FALSE;
      if ( p0varid1 != -1 ) ncvar->p0varid = p0varid1;

      if ( ncvar->bounds != UNDEFID && ncvars[ncvar->bounds].lformula && ncvars[ncvar->bounds].lformulaterms )
        {
          ncfvarid = ncvar->bounds;
          int apvarid2 = -1, bvarid2 = -1, psvarid2 = -1, avarid2 = -1, p0varid2 = -1;
          ret = 0;
          if ( ncvars[ncfvarid].lformula && ncvars[ncfvarid].lformulaterms )
            ret = scan_hybrid_formula(ncid, ncfvarid, &apvarid2, &bvarid2, &psvarid2, &avarid2, &p0varid2);
          if ( ret == 1 ) avarid2 = apvarid2;
          if ( avarid2 != -1 && bvarid2 != -1 )
            {
              ncvars[avarid2].isvar = FALSE;
              ncvars[bvarid2].isvar = FALSE;

              if ( dimid == ncvars[avarid2].dimids[0] && ncdims[ncvars[avarid2].dimids[1]].len == 2 )
                {
                  double px = 1;
                  if ( ret == 2 && p0varid1 == p0varid2 )
                    cdf_get_var_double(ncid, p0varid2, &px);

                  double abuf[dimlen*2], bbuf[dimlen*2];
                  cdf_get_var_double(ncid, avarid2, abuf);
                  cdf_get_var_double(ncid, bvarid2, bbuf);
                  /*
                  for ( int i = 0; i < dimlen; ++i )
                    printf("%d  %g %g    %g %g\n", i, abuf[i*2], abuf[i*2+1], bbuf[i*2], bbuf[i*2+1]);
                  */
                  size_t vctsize = (dimlen+1)*2;
                  double *vct = (double *) Malloc(vctsize * sizeof(double));
                  for ( size_t i = 0; i < dimlen; ++i )
                    {
                      vct[i] = abuf[i*2];
                      vct[i+dimlen+1] = bbuf[i*2];
                    }
                  vct[dimlen]     = abuf[dimlen*2-1];
                  vct[dimlen*2+1] = bbuf[dimlen*2-1];

                  if ( ret == 2 && IS_NOT_EQUAL(px, 1) )
                    for ( size_t i = 0; i < dimlen+1; ++i ) vct[i] *= px;

                  ncvar->vct = vct;
                  ncvar->vctsize = vctsize;
                }
            }
        }
    }

  return status;
}

static
void cdf_print_vars(const ncvar_t *ncvars, int nvars, const char *oname)
{
  char axis[7];
  static const char iaxis[] = {'t', 'z', 'y', 'x'};

  fprintf(stderr, "%s:\n", oname);

  for ( int ncvarid = 0; ncvarid < nvars; ncvarid++ )
    {
      int ndim = 0;
      if ( ncvars[ncvarid].isvar )
        {
          axis[ndim++] = 'v';
          axis[ndim++] = ':';
          for ( int i = 0; i < ncvars[ncvarid].ndims; i++ )