245 lines
9 KiB
C
245 lines
9 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include "grib2.h"
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g2int g2_addgrid(unsigned char *cgrib,g2int *igds,g2int *igdstmpl,g2int *ideflist,g2int idefnum)
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//$$$ SUBPROGRAM DOCUMENTATION BLOCK
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// . . . .
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// SUBPROGRAM: g2_addgrid
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// PRGMMR: Gilbert ORG: W/NP11 DATE: 2002-11-01
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//
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// ABSTRACT: This routine packs up a Grid Definition Section (Section 3)
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// and adds it to a GRIB2 message. It is used with routines "g2_create",
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// "g2_addlocal", "g2_addfield",
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// and "g2_gribend" to create a complete GRIB2 message.
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// g2_create must be called first to initialize a new GRIB2 message.
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//
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// PROGRAM HISTORY LOG:
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// 2002-11-01 Gilbert
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// 2009-01-14 Vuong Changed structure name template to gtemplate
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//
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// USAGE: int g2_addgrid(unsigned char *cgrib,g2int *igds,g2int *igdstmpl,
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// g2int *ideflist,g2int idefnum)
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// INPUT ARGUMENTS:
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// cgrib - Char array that contains the GRIB2 message to which
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// section should be added.
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// igds - Contains information needed for GRIB Grid Definition Section 3
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// Must be dimensioned >= 5.
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// igds[0]=Source of grid definition (see Code Table 3.0)
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// igds[1]=Number of grid points in the defined grid.
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// igds[2]=Number of octets needed for each
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// additional grid points definition.
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// Used to define number of
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// points in each row ( or column ) for
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// non-regular grids.
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// = 0, if using regular grid.
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// igds[3]=Interpretation of list for optional points
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// definition. (Code Table 3.11)
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// igds[4]=Grid Definition Template Number (Code Table 3.1)
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// igdstmpl - Contains the data values for the specified Grid Definition
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// Template ( NN=igds[4] ). Each element of this integer
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// array contains an entry (in the order specified) of Grid
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// Defintion Template 3.NN
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// ideflist - (Used if igds[2] != 0) This array contains the
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// number of grid points contained in each row ( or column )
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// idefnum - (Used if igds[2] != 0) The number of entries
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// in array ideflist. i.e. number of rows ( or columns )
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// for which optional grid points are defined.
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//
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// OUTPUT ARGUMENTS:
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// cgrib - Char array to contain the updated GRIB2 message.
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// Must be allocated large enough to store the entire
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// GRIB2 message.
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//
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// RETURN VALUES:
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// ierr - Return code.
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// > 0 = Current size of updated GRIB2 message
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// -1 = GRIB message was not initialized. Need to call
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// routine gribcreate first.
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// -2 = GRIB message already complete. Cannot add new section.
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// -3 = Sum of Section byte counts doesn't add to total byte count
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// -4 = Previous Section was not 1, 2 or 7.
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// -5 = Could not find requested Grid Definition Template.
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//
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// REMARKS: Note that the Grid Def Section ( Section 3 ) can only follow
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// Section 1, 2 or Section 7 in a GRIB2 message.
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//
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// ATTRIBUTES:
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// LANGUAGE: C
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// MACHINE:
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//
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//$$$
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{
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g2int ierr;
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static unsigned char G=0x47; // 'G'
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static unsigned char R=0x52; // 'R'
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static unsigned char I=0x49; // 'I'
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static unsigned char B=0x42; // 'B'
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static unsigned char seven=0x37; // '7'
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static g2int one=1,three=3,miss=65535;
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g2int lensec3,iofst,ibeg,lencurr,len;
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g2int i,j,temp,ilen,isecnum,nbits;
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gtemplate *mapgrid=0;
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ierr=0;
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//
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// Check to see if beginning of GRIB message exists
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//
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if ( cgrib[0]!=G || cgrib[1]!=R || cgrib[2]!=I || cgrib[3]!=B ) {
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printf("g2_addgrid: GRIB not found in given message.\n");
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printf("g2_addgrid: Call to routine gribcreate required to initialize GRIB messge.\n");
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ierr=-1;
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return(ierr);
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}
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//
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// Get current length of GRIB message
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//
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gbit(cgrib,&lencurr,96,32);
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//
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// Check to see if GRIB message is already complete
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//
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if ( cgrib[lencurr-4]==seven && cgrib[lencurr-3]==seven &&
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cgrib[lencurr-2]==seven && cgrib[lencurr-1]==seven ) {
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printf("g2_addgrid: GRIB message already complete. Cannot add new section.\n");
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ierr=-2;
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return(ierr);
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}
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//
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// Loop through all current sections of the GRIB message to
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// find the last section number.
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//
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len=16; // length of Section 0
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for (;;) {
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// Get section number and length of next section
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iofst=len*8;
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gbit(cgrib,&ilen,iofst,32);
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iofst=iofst+32;
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gbit(cgrib,&isecnum,iofst,8);
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len=len+ilen;
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// Exit loop if last section reached
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if ( len == lencurr ) break;
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// If byte count for each section doesn't match current
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// total length, then there is a problem.
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if ( len > lencurr ) {
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printf("g2_addgrid: Section byte counts don''t add to total.\n");
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printf("g2_addgrid: Sum of section byte counts = %ld\n",len);
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printf("g2_addgrid: Total byte count in Section 0 = %ld\n",lencurr);
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ierr=-3;
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return(ierr);
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}
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}
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//
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// Section 3 can only be added after sections 1, 2 and 7.
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//
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if ( (isecnum!=1) && (isecnum!=2) && (isecnum!=7) ) {
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printf("g2_addgrid: Section 3 can only be added after Section 1, 2 or 7.\n");
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printf("g2_addgrid: Section ',isecnum,' was the last found in given GRIB message.\n");
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ierr=-4;
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return(ierr);
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}
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//
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// Add Section 3 - Grid Definition Section
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//
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ibeg=lencurr*8; // Calculate offset for beginning of section 3
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iofst=ibeg+32; // leave space for length of section
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sbit(cgrib,&three,iofst,8); // Store section number ( 3 )
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iofst=iofst+8;
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sbit(cgrib,igds+0,iofst,8); // Store source of Grid def.
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iofst=iofst+8;
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sbit(cgrib,igds+1,iofst,32); // Store number of data pts.
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iofst=iofst+32;
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sbit(cgrib,igds+2,iofst,8); // Store number of extra octets.
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iofst=iofst+8;
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sbit(cgrib,igds+3,iofst,8); // Store interp. of extra octets.
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iofst=iofst+8;
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// if Octet 6 is not equal to zero, Grid Definition Template may
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// not be supplied.
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if ( igds[0] == 0 )
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sbit(cgrib,igds+4,iofst,16); // Store Grid Def Template num.
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else
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sbit(cgrib,&miss,iofst,16); // Store missing value as Grid Def Template num.
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iofst=iofst+16;
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//
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// Get Grid Definition Template
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//
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if (igds[0] == 0) {
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mapgrid=getgridtemplate(igds[4]);
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if (mapgrid == 0) { // undefined template
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ierr=-5;
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return(ierr);
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}
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//
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// Extend the Grid Definition Template, if necessary.
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// The number of values in a specific template may vary
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// depending on data specified in the "static" part of the
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// template.
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//
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if ( mapgrid->needext ) {
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free(mapgrid);
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mapgrid=extgridtemplate(igds[4],igdstmpl);
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}
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}
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//
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// Pack up each input value in array igdstmpl into the
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// the appropriate number of octets, which are specified in
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// corresponding entries in array mapgrid.
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//
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for (i=0;i<mapgrid->maplen;i++) {
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nbits=abs(mapgrid->map[i])*8;
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if ( (mapgrid->map[i] >= 0) || (igdstmpl[i] >= 0) )
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sbit(cgrib,igdstmpl+i,iofst,nbits);
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else {
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sbit(cgrib,&one,iofst,1);
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temp=abs(igdstmpl[i]);
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sbit(cgrib,&temp,iofst+1,nbits-1);
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}
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iofst=iofst+nbits;
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}
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// Pack template extension, if appropriate
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j=mapgrid->maplen;
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if ( mapgrid->needext && (mapgrid->extlen > 0) ) {
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for (i=0;i<mapgrid->extlen;i++) {
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nbits=abs(mapgrid->ext[i])*8;
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if ( (mapgrid->ext[i] >= 0) || (igdstmpl[j] >= 0) )
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sbit(cgrib,igdstmpl+j,iofst,nbits);
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else {
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sbit(cgrib,&one,iofst,1);
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temp=abs(igdstmpl[j]);
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sbit(cgrib,&temp,iofst+1,nbits-1);
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}
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iofst=iofst+nbits;
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j++;
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}
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}
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free(mapgrid);
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//
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// If requested,
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// Insert optional list of numbers defining number of points
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// in each row or column. This is used for non regular
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// grids.
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//
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if ( igds[2] != 0 ) {
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nbits=igds[2]*8;
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sbits(cgrib,ideflist,iofst,nbits,0,idefnum);
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iofst=iofst+(nbits*idefnum);
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}
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//
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// Calculate length of section 3 and store it in octets
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// 1-4 of section 3.
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//
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lensec3=(iofst-ibeg)/8;
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sbit(cgrib,&lensec3,ibeg,32);
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//
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// Update current byte total of message in Section 0
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//
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lencurr+=lensec3;
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sbit(cgrib,&lencurr,96,32);
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return(lencurr);
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}
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