#include <stdio.h>

#include <stdlib.h>

#include "grib2.h"

g2int g2_unpack2(unsigned char *cgrib,g2int *iofst,g2int *lencsec2,unsigned char **csec2)

////$$$  SUBPROGRAM DOCUMENTATION BLOCK

//                .      .    .                                       .

// SUBPROGRAM:    g2_unpack2

//   PRGMMR: Gilbert         ORG: W/NP11    DATE: 2002-10-31

//

// ABSTRACT: This subroutine unpacks Section 2 (Local Use Section)

//           as defined in GRIB Edition 2.

//

// PROGRAM HISTORY LOG:

// 2002-10-31  Gilbert

// 2008-12-23  Wesley   - Initialize lencsec2 Length of Local Use data

// 2010-08-05  Vuong    - If section 2 has zero length, ierr=0

//

// USAGE:    int g2_unpack2(unsigned char *cgrib,g2int *iofst,g2int *lencsec2,

//                          unsigned char **csec2)

//   INPUT ARGUMENT LIST:

//     cgrib    - char array containing Section 2 of the GRIB2 message

//     iofst    - Bit offset for the beginning of Section 2 in cgrib.

//

//   OUTPUT ARGUMENT LIST:

//     iofst    - Bit offset at the end of Section 2, returned.

//     lencsec2 - Length (in octets) of Local Use data

//     csec2    - Pointer to a char array containing local use data

//

//   RETURN VALUES:

//     ierr     - Error return code.

//                0 = no error

//                2 = Array passed is not section 2

//                6 = memory allocation error

//

// REMARKS: None

//

// ATTRIBUTES:

//   LANGUAGE: C

//   MACHINE:

//

//$$$//

{

      g2int ierr,isecnum = 0;

      g2int lensec = 0,ipos,j;

      ierr=0;

      *lencsec2=0;

      *csec2=0;    // NULL

      gbit(cgrib,&lensec,*iofst,32);        // Get Length of Section

      *iofst=*iofst+32;

      *lencsec2=lensec-5;

      gbit(cgrib,&isecnum,*iofst,8);         // Get Section Number

      *iofst=*iofst+8;

      ipos=(*iofst/8);

      if ( isecnum != 2 ) {

         ierr=2;

         *lencsec2=0;

         fprintf(stderr,"g2_unpack2: Not Section 2 data.\n");

         return(ierr);

      }

      if (*lencsec2 == 0) {

         ierr = 0;

         return(ierr);

      }

      *csec2=(unsigned char *)malloc(*lencsec2+1);

      if (*csec2 == 0) {

         ierr=6;

         *lencsec2=0;

         return(ierr);

      }

      //printf(" SAGIPO %d \n",(int)ipos);

      for (j=0;j<*lencsec2;j++) {

         *(*csec2+j)=cgrib[ipos+j];

      }

      *iofst=*iofst+(*lencsec2*8);

      return(ierr);    // End of Section 2 processing

}