#include <stdio.h>
#include "grib2.h"

g2int g2_gribend(unsigned char *cgrib)
//$$$  SUBPROGRAM DOCUMENTATION BLOCK
//                .      .    .                                       .
// SUBPROGRAM:    g2_gribend 
//   PRGMMR: Gilbert         ORG: W/NP11    DATE: 2002-10-31
//
// ABSTRACT: This routine finalizes a GRIB2 message after all grids
//   and fields have been added.  It adds the End Section ( "7777" )
//   to the end of the GRIB message and calculates the length and stores
//   it in the appropriate place in Section 0.
//   This routine is used with routines "g2_create", "g2_addlocal", 
//   "g2_addgrid", and "g2_addfield" to create a complete GRIB2 message.
//   g2_create must be called first to initialize a new GRIB2 message.
//
// PROGRAM HISTORY LOG:
// 2002-10-31  Gilbert
//
// USAGE:    int g2_gribend(unsigned char *cgrib)
//   INPUT ARGUMENT:
//     cgrib    - Char array containing all the data sections added
//                be previous calls to g2_create, g2_addlocal, g2_addgrid,
//                and g2_addfield.
//
//   OUTPUT ARGUMENTS:      
//     cgrib    - Char array containing the finalized GRIB2 message
//
//   RETURN VALUES:
//     ierr     - Return code.
//              > 0 = Length of the final GRIB2 message in bytes.
//               -1 = GRIB message was not initialized.  Need to call
//                    routine g2_create first.
//               -2 = GRIB message already complete.  
//               -3 = Sum of Section byte counts doesn't add to total byte count
//               -4 = Previous Section was not 7.
//
// REMARKS: This routine is intended for use with routines "g2_create", 
//          "g2_addlocal", "g2_addgrid", and "g2_addfield" to create a complete 
//          GRIB2 message.
//
// ATTRIBUTES:
//   LANGUAGE: C
//   MACHINE:
//
//$$$
{

      g2int iofst,lencurr,len,ilen,isecnum;
      g2int   ierr,lengrib;
      static unsigned char G=0x47;       // 'G'
      static unsigned char R=0x52;       // 'R'
      static unsigned char I=0x49;       // 'I'
      static unsigned char B=0x42;       // 'B'
      static unsigned char seven=0x37;   // '7'
 
      ierr=0;
//
//  Check to see if beginning of GRIB message exists
//
      if ( cgrib[0]!=G || cgrib[1]!=R || cgrib[2]!=I || cgrib[3]!=B ) {
        printf("g2_gribend: GRIB not found in given message.\n");
        ierr=-1;
        return (ierr);
      }
//
//  Get current length of GRIB message
//  
      gbit(cgrib,&lencurr,96,32);
//
//  Loop through all current sections of the GRIB message to
//  find the last section number.
//
      len=16;    // Length of Section 0
      for (;;) { 
      //    Get number and length of next section
        iofst=len*8;
        gbit(cgrib,&ilen,iofst,32);
        iofst=iofst+32;
        gbit(cgrib,&isecnum,iofst,8);
        len=len+ilen;
      //    Exit loop if last section reached
        if ( len == lencurr ) break;
      //    If byte count for each section doesn't match current
      //    total length, then there is a problem.
        if ( len > lencurr ) {
          printf("g2_gribend: Section byte counts don''t add to total.\n");
          printf("g2_gribend: Sum of section byte counts = %d\n",(int)len);
          printf("g2_gribend: Total byte count in Section 0 = %d\n",(int)lencurr);
          ierr=-3;
          return (ierr);
        }
      }
//
//  Can only add End Section (Section 8) after Section 7.
//
      if ( isecnum != 7 ) {
        printf("g2_gribend: Section 8 can only be added after Section 7.\n");
        printf("g2_gribend: Section %d was the last found in given GRIB message.\n",isecnum);
        ierr=-4;
        return (ierr);
      }
//
//  Add Section 8  - End Section
//
      //cgrib(lencurr+1:lencurr+4)=c7777
      cgrib[lencurr]=seven;
      cgrib[lencurr+1]=seven;
      cgrib[lencurr+2]=seven;
      cgrib[lencurr+3]=seven;

//
//  Update current byte total of message in Section 0
//
      lengrib=lencurr+4;
      sbit(cgrib,&lengrib,96,32);

      return (lengrib);

}

