File: g2_unpack3.c

package info (click to toggle)
g2clib 1.4.0-2
  • links: PTS
  • area: main
  • in suites: jessie, jessie-kfreebsd
  • size: 608 kB
  • ctags: 226
  • sloc: ansic: 4,995; makefile: 194
file content (214 lines) | stat: -rwxr-xr-x 7,858 bytes parent folder | download | duplicates (33)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
#include <stdio.h>
#include <stdlib.h>
#include "grib2.h"


g2int g2_unpack3(unsigned char *cgrib,g2int *iofst,g2int **igds,g2int **igdstmpl,
                         g2int *mapgridlen,g2int **ideflist,g2int *idefnum)
////$$$  SUBPROGRAM DOCUMENTATION BLOCK
//                .      .    .                                       .
// SUBPROGRAM:    g2_unpack3 
//   PRGMMR: Gilbert         ORG: W/NP11    DATE: 2002-10-31
//
// ABSTRACT: This routine unpacks Section 3 (Grid Definition Section)
//           as defined in GRIB Edition 2.
//
// PROGRAM HISTORY LOG:
// 2002-10-31  Gilbert
// 2009-01-14  Vuong     Changed structure name template to gtemplate
//
// USAGE:    int g2_unpack3(unsigned char *cgrib,g2int *iofst,g2int **igds,
//                          g2int **igdstmpl,g2int *mapgridlen,
//                          g2int **ideflist,g2int *idefnum)
//   INPUT ARGUMENTS:
//     cgrib    - Char array ontaining Section 3 of the GRIB2 message
//     iofst    - Bit offset for the beginning of Section 3 in cgrib.
//
//   OUTPUT ARGUMENTS:      
//     iofst    - Bit offset at the end of Section 3, returned.
//     igds     - Contains information read from the appropriate GRIB Grid 
//                Definition Section 3 for the field being returned.
//                igds[0]=Source of grid definition (see Code Table 3.0)
//                igds[1]=Number of grid points in the defined grid.
//                igds[2]=Number of octets needed for each 
//                            additional grid points definition.  
//                            Used to define number of
//                            points in each row ( or column ) for
//                            non-regular grids.  
//                            = 0, if using regular grid.
//                igds[3]=Interpretation of list for optional points 
//                            definition.  (Code Table 3.11)
//                igds[4]=Grid Definition Template Number (Code Table 3.1)
//     igdstmpl - Pointer to integer array containing the data values for 
//                the specified Grid Definition
//                Template ( NN=igds[4] ).  Each element of this integer 
//                array contains an entry (in the order specified) of Grid
//                Defintion Template 3.NN
//     mapgridlen- Number of elements in igdstmpl[].  i.e. number of entries
//                in Grid Defintion Template 3.NN  ( NN=igds[4] ).
//     ideflist - (Used if igds[2] .ne. 0)  Pointer to integer array containing
//                the number of grid points contained in each row ( or column ).
//                (part of Section 3)
//     idefnum  - (Used if igds[2] .ne. 0)  The number of entries
//                in array ideflist.  i.e. number of rows ( or columns )
//                for which optional grid points are defined.
//     ierr     - Error return code.
//                0 = no error
//                2 = Not Section 3
//                5 = "GRIB" message contains an undefined Grid Definition
//                    Template.
//                6 = memory allocation error
//
// REMARKS: 
//
// ATTRIBUTES:
//   LANGUAGE: C
//   MACHINE:
//
//$$$

{
      g2int ierr,i,j,nbits,isecnum;
      g2int lensec,ibyttem=0,isign,newlen;
      g2int *ligds,*ligdstmpl=0,*lideflist=0;
      gtemplate *mapgrid;

      ierr=0;
      *igds=0;       // NULL
      *igdstmpl=0;       // NULL
      *ideflist=0;       // NULL

      gbit(cgrib,&lensec,*iofst,32);        // Get Length of Section
      *iofst=*iofst+32;
      gbit(cgrib,&isecnum,*iofst,8);         // Get Section Number
      *iofst=*iofst+8;

      if ( isecnum != 3 ) {
         ierr=2;
         *idefnum=0;
         *mapgridlen=0;
        // fprintf(stderr,"g2_unpack3: Not Section 3 data.\n");
         return(ierr);
      }

      ligds=(g2int *)calloc(5,sizeof(g2int));
      *igds=ligds;

      gbit(cgrib,ligds+0,*iofst,8);     // Get source of Grid def.
      *iofst=*iofst+8;
      gbit(cgrib,ligds+1,*iofst,32);    // Get number of grid pts.
      *iofst=*iofst+32;
      gbit(cgrib,ligds+2,*iofst,8);     // Get num octets for opt. list
      *iofst=*iofst+8;
      gbit(cgrib,ligds+3,*iofst,8);     // Get interpret. for opt. list
      *iofst=*iofst+8;
      gbit(cgrib,ligds+4,*iofst,16);    // Get Grid Def Template num.
      *iofst=*iofst+16;

      if (ligds[4] != 65535) {
        //   Get Grid Definition Template
        mapgrid=getgridtemplate(ligds[4]);
        if (mapgrid == 0) {         // undefined template
          ierr=5;
          return(ierr);
        }
        *mapgridlen=mapgrid->maplen;
        //
        //   Unpack each value into array igdstmpl from the
        //   the appropriate number of octets, which are specified in
        //   corresponding entries in array mapgrid.
        //
        if (*mapgridlen > 0) {
           ligdstmpl=0;
           ligdstmpl=(g2int *)calloc(*mapgridlen,sizeof(g2int));
           if (ligdstmpl == 0) {
              ierr=6;
              *mapgridlen=0;
              *igdstmpl=0;    //NULL
              if( mapgrid != 0 ) free(mapgrid);
              return(ierr);
           }
           else {
              *igdstmpl=ligdstmpl;
           }
        }
        ibyttem=0;
        for (i=0;i<*mapgridlen;i++) {
          nbits=abs(mapgrid->map[i])*8;
          if ( mapgrid->map[i] >= 0 ) {
            gbit(cgrib,ligdstmpl+i,*iofst,nbits);
          }
          else {
            gbit(cgrib,&isign,*iofst,1);
            gbit(cgrib,ligdstmpl+i,*iofst+1,nbits-1);
            if (isign == 1) ligdstmpl[i]=-1*ligdstmpl[i];
          }
          *iofst=*iofst+nbits;
          ibyttem=ibyttem+abs(mapgrid->map[i]);
        }
        //
        //   Check to see if the Grid Definition Template needs to be
        //   extended.
        //   The number of values in a specific template may vary
        //   depending on data specified in the "static" part of the
        //   gtemplate.
        //
        if ( mapgrid->needext == 1 ) {
          free(mapgrid);
          mapgrid=extgridtemplate(ligds[4],ligdstmpl);
          //   Unpack the rest of the Grid Definition Template
          newlen=mapgrid->maplen+mapgrid->extlen;
          ligdstmpl=(g2int *)realloc(ligdstmpl,newlen*sizeof(g2int));
          *igdstmpl=ligdstmpl;
          j=0;
          for (i=*mapgridlen;i<newlen;i++) {
            nbits=abs(mapgrid->ext[j])*8;
            if ( mapgrid->ext[j] >= 0 ) {
              gbit(cgrib,ligdstmpl+i,*iofst,nbits);
            }
            else {
              gbit(cgrib,&isign,*iofst,1);
              gbit(cgrib,ligdstmpl+i,*iofst+1,nbits-1);
              if (isign == 1) ligdstmpl[i]=-1*ligdstmpl[i];
            }
            *iofst=*iofst+nbits;
            ibyttem=ibyttem+abs(mapgrid->ext[j]);
            j++;
          }
          *mapgridlen=newlen;
        }
        if( mapgrid->ext != 0 ) free(mapgrid->ext);
        if( mapgrid != 0 ) free(mapgrid);
      }
      else {              // No Grid Definition Template
        *mapgridlen=0;
        *igdstmpl=0;
      }
      //
      //   Unpack optional list of numbers defining number of points
      //   in each row or column, if included.  This is used for non regular
      //   grids.
      //
      if ( ligds[2] != 0 ) {
         nbits=ligds[2]*8;
         *idefnum=(lensec-14-ibyttem)/ligds[2];
         if (*idefnum > 0) lideflist=(g2int *)calloc(*idefnum,sizeof(g2int));
         if (lideflist == 0) {
            ierr=6;
            *idefnum=0;
            *ideflist=0;   //NULL
            return(ierr);
         }
         else {
            *ideflist=lideflist;
         }
         gbits(cgrib,lideflist,*iofst,nbits,0,*idefnum);
         *iofst=*iofst+(nbits*(*idefnum));
      }
      else {
         *idefnum=0;
         *ideflist=0;    // NULL
      }
      
      return(ierr);    // End of Section 3 processing
}