#include <stdio.h> /* standard I/O header file */
#include <stdlib.h>
#include <string.h>
#include "dprints.h" /* for dprints & func prototype*/
#include "gribfuncs.h" /* prototypes */
/* PROGRAMMER : Steve Lowe and Todd Kienitz, SAIC Monterey
DATE : February 7, 1996
Oct. 1996 by Alice Nakajima, SAIC Monterey
*
*********************************************************************
* A. FUNCTION: grib_dec
* decode a Gridded Binary (GRIB edition 1) format message
*
* INTERFACE:
* int grib_dec (curr_ptr, pds, gds, bds_head, bms, ppgrib_data, errmsg)
*
* ARGUMENTS (I=input, O=output, I&O=input and output):
* (I) char *curr_ptr;
* pointer to block containing GRIB message to decode;
* (O) PDS_INPUT *pds ;
* to be filled with decoded Product Defn Section info;
* (O) grid_desc_sec *gds;
* to be filled with decoded Binary Data Section info;
* (O) BDS_HEAD_INPUT *bds_head;
* to be filled with decoded Binary Data Section info;
* (O) BMS_INPUT *bms;
* to be filled with decoded Bitmap Section info;
* (O) float **ppgrib_data;
* points to NULL upon entry; upon successful exit, points to newly
* malloced Float array filled with unpacked and restored data;
* (O) char *errmsg;
* Empty array, Returned filled if error occurred;
*
* RETURN CODE:
* 0> Success, **ppgrib_data now points to a block containing
* the unpacked & restored data (float);
* 1> Fail: first 4 bytes of curr_ptr is not 'GRIB'
* 2> Fail: last 4 bytes of curr_ptr is not '7777'
* 3> Fail: not Grib Edition 1
* 4> Fail: unknown projection type;
***********************************************************************
*/
#if PROTOTYPE_NEEDED
int grib_dec (char *curr_ptr, PDS_INPUT *pds, grid_desc_sec *gds,
BDS_HEAD_INPUT *bds_head, BMS_INPUT *bms, float **ppgrib_data,
char *errmsg)
#else
int grib_dec (curr_ptr, pds, gds, bds_head, bms, ppgrib_data, errmsg)
char *curr_ptr; /*input= ptr to 1st byte of GRIB message block*/
PDS_INPUT *pds; /* output=ptr to Internal PDS struct*/
grid_desc_sec *gds; /* output=ptr to Internal GDS struct*/
BDS_HEAD_INPUT*bds_head; /*out=ptr to Internal BDS header struct*/
BMS_INPUT *bms; /*output=ptr to Internal bitmap section struct*/
float **ppgrib_data; /*outp=ptr to nothing upon entry; upon exit, */
/* points to a newly malloced array of floats; */
char *errmsg; /* output= empty unless Error happens */
#endif
{
char *func="grib_dec";
unsigned long lMessageSize; /* message and section size */
long edition; /* GRIB edition number */
int flag; /* tests if a condition has happened */
int gds_flag; /* set if Gds present */
int nReturn = 0;
unsigned long skip;
float *outdata;
int xsize;
int j;
/*
*
* A.0 DEBUG printing
*/
DPRINT1 ("Entering %s\n", func);
DPRINT6 (
"curr_ptr=%ld, pds=%ld, gds=%ld\nbds_head=%ld, bms=%ld, ppgrib_data=%ld\n",
curr_ptr, pds, gds, bds_head, bms, ppgrib_data);
/*
*
* A.1 IF (incoming pointer is not at 'GRIB')
* RETURN 1 !errmsg filled
* ENDIF
*/
if(strncmp(curr_ptr,"GRIB",4) != 0) {
sprintf (errmsg,"%s: no 'GRIB' at beg. of this msg\n", func);
nReturn= (1); /* GRIB not found */
}
/*
*
* A.2 FUNCTION gbyte !get total message length from IDS
*/
skip=32;
gbyte(curr_ptr,&lMessageSize,&skip,24);
DPRINT0 ("lMessageSize\n");
/*
*
* A.3 IF (Message does not end with '7777')
* RETURN 2 !errmsg filled
* ENDIF
*/
if(strncmp((curr_ptr + lMessageSize - 4),"7777",4)!=0) {
DPRINT1 ("%s: no '7777' at end of this msg\n", func);
sprintf (errmsg,"%s: no '7777' at end of this msg\n", func);
nReturn= 2; goto BYE;
}
/*
*
* A.4 EXTRACT the GRIB edition out of Section 0
* IF (not GRIB edition 1)
* RETURN 3 !errmsg filled
* ENDIF
*/
edition = (long) curr_ptr[7]; /* get edition */
pds->usEd_num = (unsigned short) edition;
if(edition != 1) {
DPRINT1 ("%s: error, not Grib Edition 1 \n", func);
sprintf (errmsg,"%s: not Grib Edition 1 \n", func);
nReturn=(3); goto BYE;
}
/*
*
* A.5 MOVE pointer to the Product Definition section
*/
curr_ptr = curr_ptr + 8;
/*
*
* A.6 FUNCTION gribgetpds !decode the PDS
* RETURN error code if fails !errmsg filled
*/
if( nReturn= gribgetpds(curr_ptr, pds, errmsg)) {
DPRINT2 ("%s: error=%d in grib get pds;\n", func, nReturn);
upd_child_errmsg (func, errmsg);
goto BYE;
}
/*
*
* A.7 MOVE pointer to the end of PDS
*/
curr_ptr += pds->uslength;
/*
*
* A.8 IF (GDS is present)
*/
gds_flag = pds->usGds_bms_id >> 7 & 1;
if(gds_flag) /* grid description section present */
{
/*
* A.8.1 FUNCTION gribgetgds !decode GDS
* RETURN error code if fails !errmsg filled
*/
if( nReturn=gribgetgds(curr_ptr, gds, errmsg)) {
DPRINT2 ("%s: error=%d in grib get GDS;\n", func, nReturn);
upd_child_errmsg (func, errmsg);
goto BYE;
}
/*
* A.8.2 MOVE the cursor to the next section (either BMS/BDS)
*/
curr_ptr += gds->head.uslength;
/*
* A.8.3 SET the number of data points depending on Projection
*/
switch(gds->head.usData_type)
{
case LATLON_PRJ: /* Lat/Lon Grid */
case GAUSS_PRJ: /* Gaussian Latitude/Longitude grid */
case ROT_LATLON_PRJ: /* Rotated Lat/Lon */
case ROT_GAUSS_PRJ: /* Rotated Gaussian */
case STR_LATLON_PRJ: /* Stretched Lat/Lon */
case STR_GAUSS_PRJ : /* Stretched Gaussian */
case STR_ROT_LATLON_PRJ : /* Stretched and Rotated Lat/Lon */
case STR_ROT_GAUSS_PRJ : /* Stretched and Rotated Gaussian */
bds_head->ulGrid_size = gds->llg.usNi * gds->llg.usNj;
break;
case MERC_PRJ: /* Mercator Grid */
bds_head->ulGrid_size = gds->merc.cols * gds->merc.rows;
break;
case LAMB_PRJ: /* Lambert Conformal */
case ALBERS_PRJ: /* Albers equal-area */
case OBLIQ_LAMB_PRJ: /* Oblique Lambert Conformal */
bds_head->ulGrid_size = gds->lam.iNx * gds->lam.iNy;
break;
case POLAR_PRJ: /* Polar Stereographic */
bds_head->ulGrid_size = gds->pol.usNx * gds->pol.usNy;
break;
default: /* unknown */
DPRINT2 ("%s: unknown usData_type=%d\n",func,gds->head.usData_type);
sprintf(errmsg,"%s: unknown usData_type=%d\n",
func, gds->head.usData_type);
nReturn= (4); goto BYE;
}
}
/*
* A.8 ENDIF (GDS is present)
*/
/*
*
* A.9 IF (bitmap Section is present)
*/
flag = pds->usGds_bms_id >> 6 & 1;
if(flag) /* bit map section present */
{
/*
* A.9.1 FUNCTION gribgetbms !decode BMS
* RETURN error code if fails !errmsg filled
*/
if( nReturn=gribgetbms(curr_ptr,bms,gds_flag, bds_head->ulGrid_size,errmsg))
{
DPRINT2 ("%s: error=%d in grib get BMS;\n",func,nReturn);
upd_child_errmsg (func, errmsg);
goto BYE;
}
/*
* A.9.2 MOVE the cursor to beginning of Binary Data Section
*/
curr_ptr += bms->uslength;
} /* Bms present */
/*
* A.9 ENDIF !bms present
*/
/*
*
* A.10 FUNCTION gribgetbds()
* RETURN error code if failed !errmsg filled
*/
if(nReturn=gribgetbds(curr_ptr, pds->sDec_sc_fctr, bms, gds, ppgrib_data,
bds_head, errmsg))
{
DPRINT2 ("%s: error=%d in grib get BDS;\n",func,nReturn);
upd_child_errmsg (func, errmsg);
goto BYE;
}
/*
*
* A.11 SET return code to 0 !no errors
*/
nReturn = 0;
/*
*
* A.12 RETURN return code;
*/
BYE:
DPRINT2 ("Exit %s, Stat=%d\n", func, nReturn);
return(nReturn);
/*
*
* END OF FUNCTION
*
*
*/
}