GRASS GIS 8 Programmer's Manual  8.4.0dev(2024)-c17eaff561
segment/put.c
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1 /**
2  * \file lib/segment/put.c
3  *
4  * \brief Segment write routines.
5  *
6  * This program is free software under the GNU General Public License
7  * (>=v2). Read the file COPYING that comes with GRASS for details.
8  *
9  * \author GRASS GIS Development Team
10  *
11  * \date 2005-2018
12  */
13 
14 #include <string.h>
15 #include <grass/gis.h>
16 #include "local_proto.h"
17 
18 /*bugfix: buf: char* vs int* -> wrong pointer arithmetics!!!. Pierre de Mouveaux
19  * - 09 april 2000 */
20 /* int Segment_put (SEGMENT *SEG,int *buf,int row,int col) */
21 
22 /**
23  * \fn int Segment_put (SEGMENT *SEG, void *buf, int row, int col)
24  *
25  * \brief Write value to segment file.
26  *
27  * Provides random write access to the segmented data. It
28  * copies <i>len</i> bytes of data from <b>buf</b> into the segment
29  * structure <b>seg</b> for the corresponding <b>row</b> and <b>col</b> in
30  * the original data matrix.
31  *
32  * The data is not written to disk immediately. It is stored in a memory segment
33  * until the segment routines decide to page the segment to disk.
34  *
35  * \param[in,out] seg segment
36  * \param[in] buf value to write to segment
37  * \param[in] row
38  * \param[in] col
39  * \return 1 if successful
40  * \return -1 if unable to seek or write segment file
41  */
42 
43 int Segment_put(SEGMENT *SEG, const void *buf, off_t row, off_t col)
44 {
45  int index, n, i;
46 
47  if (SEG->cache) {
48  memcpy(SEG->cache + ((size_t)row * SEG->ncols + col) * SEG->len, buf,
49  SEG->len);
50 
51  return 1;
52  }
53 
54  SEG->address(SEG, row, col, &n, &index);
55  if ((i = seg_pagein(SEG, n)) < 0) {
56  G_warning("segment lib: put: pagein failed");
57  return -1;
58  }
59 
60  SEG->scb[i].dirty = 1;
61 
62  memcpy(&SEG->scb[i].buf[index], buf, SEG->len);
63 
64  return 1;
65 }
void G_warning(const char *,...) __attribute__((format(printf
int seg_pagein(SEGMENT *SEG, int n)
Internal use only.
Definition: pagein.c:35
int Segment_put(SEGMENT *SEG, const void *buf, off_t row, off_t col)
Definition: segment/put.c:43
char dirty
Definition: segment.h:47
char * buf
Definition: segment.h:46
int len
Definition: segment.h:23
int(* address)(const struct SEGMENT *, off_t, off_t, int *, int *)
Definition: segment.h:39
struct SEGMENT::scb * scb
off_t ncols
Definition: segment.h:22
char * cache
Definition: segment.h:61