100 lines
3.1 KiB
C
100 lines
3.1 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_unpack1(unsigned char *cgrib,g2int *iofst,g2int **ids,g2int *idslen)
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/*//$$$ SUBPROGRAM DOCUMENTATION BLOCK
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// . . . .
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// SUBPROGRAM: g2_unpack1
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// PRGMMR: Gilbert ORG: W/NP11 DATE: 2002-10-29
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//
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// ABSTRACT: This subroutine unpacks Section 1 (Identification Section)
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// as defined in GRIB Edition 2.
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//
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// PROGRAM HISTORY LOG:
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// 2002-10-29 Gilbert
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//
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// USAGE: int g2_unpack1(unsigned char *cgrib,g2int *iofst,g2int **ids,
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// g2int *idslen)
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// INPUT ARGUMENTS:
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// cgrib - char array containing Section 1 of the GRIB2 message
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// iofst - Bit offset for the beginning of Section 1 in cgrib.
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//
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// OUTPUT ARGUMENTS:
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// iofst - Bit offset at the end of Section 1, returned.
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// ids - address of pointer to integer array containing information
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// read from Section 1, the Identification section.
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// ids[0] = Identification of originating Centre
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// ( see Common Code Table C-1 )
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// ids[1] = Identification of originating Sub-centre
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// ids[2] = GRIB Master Tables Version Number
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// ( see Code Table 1.0 )
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// ids[3] = GRIB Local Tables Version Number
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// ( see Code Table 1.1 )
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// ids[4] = Significance of Reference Time (Code Table 1.2)
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// ids[5] = Year ( 4 digits )
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// ids[6] = Month
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// ids[7] = Day
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// ids[8] = Hour
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// ids[9] = Minute
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// ids[10] = Second
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// ids[11] = Production status of processed data
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// ( see Code Table 1.3 )
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// ids[12] = Type of processed data ( see Code Table 1.4 )
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// idslen - Number of elements in ids[].
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//
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// RETURN VALUES:
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// ierr - Error return code.
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// 0 = no error
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// 2 = Array passed is not section 1
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// 6 = memory allocation error
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//
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// REMARKS:
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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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{
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g2int i,lensec,nbits,ierr,isecnum;
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g2int mapid[13]={2,2,1,1,1,2,1,1,1,1,1,1,1};
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ierr=0;
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*idslen=13;
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*ids=0;
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gbit(cgrib,&lensec,*iofst,32); // Get Length of Section
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*iofst=*iofst+32;
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gbit(cgrib,&isecnum,*iofst,8); // Get Section Number
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*iofst=*iofst+8;
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if ( isecnum != 1 ) {
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ierr=2;
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*idslen=13;
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fprintf(stderr,"g2_unpack1: Not Section 1 data.\n");
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return(ierr);
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}
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//
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// Unpack each value into array ids from the
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// the appropriate number of octets, which are specified in
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// corresponding entries in array mapid.
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//
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*ids=(g2int *)calloc(*idslen,sizeof(g2int));
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if (*ids == 0) {
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ierr=6;
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return(ierr);
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}
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for (i=0;i<*idslen;i++) {
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nbits=mapid[i]*8;
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gbit(cgrib,*ids+i,*iofst,nbits);
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*iofst=*iofst+nbits;
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}
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return(ierr); // End of Section 1 processing
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}
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