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Functions
int	Segment_open (SEGMENT , char , off_t, off_t, int, int, int, int)
	Initialize segment structure and open segment file.

int	Segment_close (SEGMENT *)
	Free memory allocated to segment, delete temp file.

int	Segment_flush (SEGMENT *)
	Flush pending updates to disk.

int	Segment_format (int, off_t, off_t, int, int, int)
	Format a segment file.

int	Segment_format_nofill (int, off_t, off_t, int, int, int)
	Format a segment file.

int	Segment_get (SEGMENT , void , off_t, off_t)
	Get value from segment file.

int	Segment_get_row (const SEGMENT , void , off_t)

int	Segment_init (SEGMENT *, int, int)
	Initialize segment structure.

int	Segment_put (SEGMENT , const void , off_t, off_t)

int	Segment_put_row (const SEGMENT , const void , off_t)
	Write row to segment file.

int	Segment_release (SEGMENT *)
	Free memory allocated to segment.

Function Documentation

◆ Segment_close()

int Segment_close ( SEGMENT * SEG )

Free memory allocated to segment, delete temp file.

Releases the allocated memory associated with the segment file seg and deletes the temporary file.

Parameters

[in,out] SEG segment

Returns: 1 if successful; -1 if SEGMENT is not available (not open)

Definition at line 32 of file segment/close.c.

References close, G_free(), NULL, Segment_release(), and unlink.

◆ Segment_flush()

int Segment_flush ( SEGMENT * SEG )

Flush pending updates to disk.

Forces all pending updates generated by Segment_put() to be written to the segment file seg. Must be called after the final Segment_put() to force all pending updates to disk. Must also be called before the first call to Segment_get_row.

Parameters

[in] SEG segment

Returns: always returns 0

Definition at line 29 of file flush.c.

References seg_pageout().

◆ Segment_format()

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]	fd	file descriptor
[in]	nrows	number of non-segmented rows
[in]	ncols	number of non-segmented columns
[in]	srows	segment rows
[in]	scols	segment columns
[in]	len	length of data type

Returns: 1 of successful; -1 if unable to seek or write fd; -3 if illegal parameters are passed

Definition at line 60 of file segment/format.c.

◆ Segment_format_nofill()

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]	fd	file descriptor
[in]	nrows	number of non-segmented rows
[in]	ncols	number of non-segmented columns
[in]	srows	segment rows
[in]	scols	segment columns
[in]	len	length of data type

Returns: 1 of successful; -1 if unable to seek or write fd; -3 if illegal parameters are passed

Definition at line 97 of file segment/format.c.

Referenced by Segment_open().

◆ Segment_get()

int Segment_get	(	SEGMENT *	SEG,
		void *	buf,
		off_t	row,
		off_t	col
	)

Get value from segment file.

Provides random read access to the segmented data. It gets len bytes of data into buf from the segment file seg for the corresponding row and col in the original data matrix.

Parameters

[in]	SEG	segment
[in,out]	buf	value return buffer
[in]	row
[in]	col

Returns: 1 of successful; -1 if unable to seek or read segment file

Definition at line 36 of file segment/get.c.

References UntypedStream::buf, and seg_pagein().

Referenced by P_Read_Raster_Region_Map(), and P_Regular_Points().

◆ Segment_get_row()

int Segment_get_row	(	const SEGMENT *	SEG,
		void *	buf,
		off_t	row
	)

Definition at line 43 of file segment/get_row.c.

References _, err(), G_warning(), read, and AMI_STREAM< T >::seek().

◆ Segment_init()

int Segment_init	(	SEGMENT *	SEG,
		int	fd,
		int	nseg
	)

Initialize segment structure.

Initializes the seg structure. The file on fd is a segment file created by Segment_format() and must be open for reading and writing. The segment file configuration parameters nrows, ncols, srows, scols, and len, as written to the file by Segment_format(), are read from the file and stored in the seg structure. nsegs specifies the number of segments that will be retained in memory. The minimum value allowed is 1.

Note: The size of a segment is scols*srows*len plus a few bytes for managing each segment.

Parameters

[in,out]	SEG	segment
[in]	fd	file descriptor
[in]	nseg	number of segments to remain in memory

Returns: 1 if successful; -1 if unable to seek or read segment file; -2 if out of memory

Definition at line 55 of file segment/init.c.

References err(), G_warning(), and seg_setup().

Referenced by Segment_open().

◆ Segment_open()

int Segment_open	(	SEGMENT *	SEG,
		char *	fname,
		off_t	nrows,
		off_t	ncols,
		int	srows,
		int	scols,
		int	len,
		int	nseg
	)

Initialize segment structure and open segment file.

Initializes the seg structure and prepares a temporary file. This fn is a wrapper for Segment_format() and Segment_init()

Note: The file with name fname will be created anew.

Parameters

[in,out]	SEG	segment
[in]	fname	file name
[in]	nrows	number of non-segmented rows
[in]	ncols	number of non-segmented columns
[in]	srows	segment rows
[in]	scols	segment columns
[in]	len	length of data type
[in]	nseg	number of segments to remain in memory

Returns: 1 if successful; -1 if file name is invalid; -2 if file write error; -3 if illegal parameters are passed; -4 if file could not be re-opened; -5 if prepared file could not be read; -6 if out of memory

Definition at line 44 of file segment/open.c.

References _, access, close, creat, F_OK, G_calloc, G_store(), G_verbose_message(), G_warning(), NULL, open, Segment_format_nofill(), Segment_init(), and unlink.

◆ Segment_put()

int Segment_put	(	SEGMENT *	SEG,
		const void *	buf,
		off_t	row,
		off_t	col
	)

Definition at line 42 of file segment/put.c.

References UntypedStream::buf, G_warning(), and seg_pagein().

Referenced by P_Regular_Points().

◆ Segment_put_row()

int Segment_put_row	(	const SEGMENT *	SEG,
		const void *	buf,
		off_t	row
	)

Write row to segment file.

Transfers non-segmented matrix data, row by row, into a segment file. seg is the segment structure that was configured from a call to Segment_init(). buf should contain ncols*len bytes of data to be transferred to the segment file. row specifies the row from the data matrix being transferred.

Parameters

[in,out]	SEG	segment
[in]	buf	data to write to segment
[in]	row

Returns: 1 if successful; -1 if unable to seek or write segment file

Definition at line 43 of file segment/put_row.c.

References _, err(), G_warning(), AMI_STREAM< T >::seek(), and write.

◆ Segment_release()

int Segment_release ( SEGMENT * SEG )

Free memory allocated to segment.

Releases the allocated memory associated with the segment file seg.

Note: Does not close the file. Does not flush the data which may be pending from previous Segment_put() calls.

Parameters

[in,out] SEG segment

Returns: 1 if successful; -1 if SEGMENT is not available (not open)

Definition at line 33 of file segment/release.c.

References UntypedStream::buf, and G_free().

Referenced by Segment_close().

Functions

Function Documentation

◆ Segment_close()

◆ Segment_flush()

◆ Segment_format()

◆ Segment_format_nofill()

◆ Segment_get()

◆ Segment_get_row()

◆ Segment_init()

◆ Segment_open()

◆ Segment_put()

◆ Segment_put_row()

◆ Segment_release()