GRASS GIS 7 Programmer's Manual  7.5.svn(2017)-r71933
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segment/format.c File Reference

Segment formatting routines. More...

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include <grass/gis.h>
#include <grass/glocale.h>
#include "local_proto.h"
Include dependency graph for segment/format.c:

Go to the source code of this file.

Functions

int Segment_format (int fd, off_t nrows, off_t ncols, int srows, int scols, int len)
 Format a segment file. More...
 
int Segment_format_nofill (int fd, off_t nrows, off_t ncols, int srows, int scols, int len)
 Format a segment file. More...
 

Detailed Description

Segment formatting routines.

This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

Author
GRASS GIS Development Team
Date
2005-2009

Definition in file segment/format.c.

Function Documentation

int Segment_format ( int  fd,
off_t  nrows,
off_t  ncols,
int  srows,
int  scols,
int  len 
)

Format a segment file.

The segmentation routines require a disk file to be used for paging segments in and out of memory. This routine formats the file open for write on file descriptor fd for use as a segment file.

A segment file must be formatted before it can be processed by other segment routines. The configuration parameters nrows, ncols, srows, scols, and len are written to the beginning of the segment file which is then filled with zeros.

The corresponding nonsegmented data matrix, which is to be transferred to the segment file, is nrows by ncols. The segment file is to be formed of segments which are srows by scols. The data items have length len bytes. For example, if the data type is int, len is sizeof(int).

Parameters
[in]fdfile descriptor
[in]nrowsnumber of non-segmented rows
[in]ncolsnumber of non-segmented columns
[in]srowssegment rows
[in]scolssegment columns
[in]lenlength of data type
Returns
1 of successful
-1 if unable to seek or write fd
-3 if illegal parameters are passed

Definition at line 63 of file segment/format.c.

Referenced by Segment_open().

int Segment_format_nofill ( int  fd,
off_t  nrows,
off_t  ncols,
int  srows,
int  scols,
int  len 
)

Format a segment file.

The segmentation routines require a disk file to be used for paging segments in and out of memory. This routine formats the file open for write on file descriptor fd for use as a segment file.

A segment file must be formatted before it can be processed by other segment routines. The configuration parameters nrows, ncols, srows, scols, and len are written to the beginning of the segment file which is then filled with zeros.

The corresponding nonsegmented data matrix, which is to be transferred to the segment file, is nrows by ncols. The segment file is to be formed of segments which are srows by scols. The data items have length len bytes. For example, if the data type is int, len is sizeof(int).

Note: This version of the function does not fill in the initialized data structures with zeros.

Parameters
[in]fdfile descriptor
[in]nrowsnumber of non-segmented rows
[in]ncolsnumber of non-segmented columns
[in]srowssegment rows
[in]scolssegment columns
[in]lenlength of data type
Returns
1 of successful
-1 if unable to seek or write fd
-3 if illegal parameters are passed

Definition at line 101 of file segment/format.c.