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/**
* Copyright 1981-2007 ECMWF
*
* Licensed under the GNU Lesser General Public License which
* incorporates the terms and conditions of version 3 of the GNU
* General Public License.
* See LICENSE and gpl-3.0.txt for details.
*/
#include <stdio.h>
#include <string.h>
#include "fortint.h"
/* defines for FORTRAN subroutine */
#ifndef CRAY
#ifdef FORTRAN_NO_UNDERSCORE
#define SOFFSET soffset
#else
#define SOFFSET soffset_
#endif
#endif
#define ERROR(a,b) {perror(a);return b;}
#define GRIB 0x47524942
#define len3oct(p) ((((long)*(p))<<16) + (((long)*(p+1))<<8) + (long)*(p+2))
#define BIT1 0x80
#define BIT2 0x40
#define BIT3 0x20
#define BIT4 0x10
#define BIT5 0x08
#define BIT6 0x04
#define BIT7 0x02
#define BIT8 0x01
static int grab(unsigned char * , unsigned char * , long ,long ,long * );
fortint soffset_(
unsigned char * buffer,
fortint* is0,
fortint* is1,
fortint* is2,
fortint* is3,
fortint* is4,
fortint* iedition) {
long s0, s1, s2, s3, s4, edition;
int large = 0;
int found = 0;
int code = 0;
long bytes_read = 0, advance;
unsigned char p, edit_num, flag23;
unsigned char size[3];
int section0 = 8, section1, section2, section3, section4;
long total;
unsigned char grp_7777[5];
/* Read bytes until "GRIB" found */
do
{
if( grab(buffer, &p, 1, 1, &bytes_read) != 0) return 1;
code = ( (code << 8) + p ) & 0xFFFFFFFF;
if (code == GRIB ) found = 1;
} while ( ! found );
s0 = bytes_read - 4;
bytes_read = 4;
/* Now find out which edition of GRIB is present (default is 1) */
edition = 1;
s1 = s0 + 8;
if( (*(buffer+21-s0) == '\0') && (*(buffer+22-s0) == '\0') )
{
edition = -1; /* GRIB edition -1 */
s1 = s0;
section1 = 20;
section0 = 4;
}
else
{
if( grab(buffer, size, 3, 1, &bytes_read) != 0) return 1;
total = len3oct(size);
if( total == 24 )
{
/* Move past the edition number */
if( grab(buffer, &edit_num, 1, 1, &bytes_read) != 0) return 1;
edition = 0; /* GRIB edition 0 */
section1 = 24;
s1 = s0 + 4;
section0 = 4;
}
}
if( edition == 1 )
{
/* See if it is an extra large (wave) product */
if( total > 0x800000 ) {
total = (total&0x7fffff) * 120;
large = 1;
}
/* Move past the edition number */
if( grab(buffer, &edit_num, 1, 1, &bytes_read) != 0) return 1;
/* Read length of section 1 */
if( grab(buffer, size, 3, 1, &bytes_read) != 0) return 1;
section1 = len3oct(size);
}
/* Now figure out if sections 2/3 are present */
advance = 4;
bytes_read += advance;
if( grab(buffer, &flag23, 1, 1, &bytes_read) != 0) return 1;
section2 = flag23 & BIT1;
section3 = flag23 & BIT2;
/* Advance to end of section 1 */
advance = section1 - (bytes_read - section0);
bytes_read += advance;
/* Read section 2 length if it is given*/
if( section2 )
{
s2 = s0 + bytes_read;
if( grab(buffer, size, 3, 1, &bytes_read) != 0) return 1;
section2 = len3oct(size);
advance = section2 - (bytes_read - section0 - section1);
bytes_read += advance;
}
else
{
section2 = 0;
s2 = 0;
}
/* Read section 3 length if it is given*/
if( section3 )
{
s3 = s0 + bytes_read;
if( grab(buffer, size, 3, 1, &bytes_read) != 0) return 1;
section3 = len3oct(size);
advance = section3 - (bytes_read - section0 - section1 - section2);
bytes_read += advance;
}
else
{
section3 = 0;
s3 = 0;
}
/* Read section 4 length */
s4 = s0 + bytes_read;
if( grab(buffer, size, 3, 1, &bytes_read) != 0) return 1;
section4 = len3oct(size);
if( large ) section4 = total + 3 - bytes_read - section4;
advance = section4 - (bytes_read - section0 - section1 - section2 - section3);
bytes_read += advance;
/* Check 7777 group is in the expected place */
if( grab(buffer, grp_7777, 4, 1, &bytes_read) != 0) return 1;
grp_7777[4] = '\0';
if( strcmp((char *)grp_7777,"7777") != 0 )
ERROR("7777 group not found", 15);
/* Success! */
*is0 = (fortint) s0;
*is1 = (fortint) s1;
*is2 = (fortint) s2;
*is3 = (fortint) s3;
*is4 = (fortint) s4;
*iedition = (fortint) edition;
return 0;
}
fortint soffset(
unsigned char * buffer,
fortint* is0,
fortint* is1,
fortint* is2,
fortint* is3,
fortint* is4,
fortint* iedition) {
return soffset_(buffer,is0,is1,is2,is3,is4,iedition);
}
static int grab(unsigned char * buffer, unsigned char * where, long size,long cnt,long * num_bytes_read)
{
long number = size*cnt;
memcpy(where, (buffer+(*num_bytes_read)), number);
*num_bytes_read += number;
return 0;
}
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