GRASS GIS 8 Programmer's Manual 8.4.1(2025)-45ca3179ab
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put_row.c
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1/**
2 * \file lib/segment/put_row.c
3 *
4 * \brief Write segment row 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 <stdio.h>
15#include <string.h>
16#include <errno.h>
17#include <unistd.h>
18#include <grass/gis.h>
19#include "local_proto.h"
20
21/* buf is CELL * WRAT code */
22/* int Segment_put_row (SEGMENT *SEG, CELL *buf,int row) */
23
24/**
25 * \brief Write row to segment file.
26 *
27 * Transfers non-segmented matrix data, row by row, into a segment
28 * file. <b>seg</b> is the segment structure that was configured from a
29 * call to <i>Segment_init()</i>. <b>buf</b> should contain
30 * <em>ncols*len</em> bytes of data to be transferred to the segment
31 * file. <b>row</b> specifies the row from the data matrix being
32 * transferred.
33 *
34 * \param[in,out] SEG segment
35 * \param[in] buf data to write to segment
36 * \param[in] row
37 * \return 1 if successful
38 * \return -1 if unable to seek or write segment file
39 */
40
41int Segment_put_row(const SEGMENT *SEG, const void *buf, off_t row)
42{
43 int size;
44 off_t ncols;
45 int scols;
46 int n, index;
47 int result;
48 off_t col;
49
50 if (SEG->cache) {
51 memcpy(SEG->cache + ((size_t)row * SEG->ncols) * SEG->len, buf,
52 SEG->len * SEG->ncols);
53
54 return 1;
55 }
56
57 ncols = SEG->ncols - SEG->spill;
58 scols = SEG->scols;
59 size = scols * SEG->len;
60 /* printf("Segment_put_row ncols: %d, scols %d, size: %d, col %d, row:
61 * %d, SEG->fd: %d\n",ncols,scols,size,col,row, SEG->fd); */
62
63 for (col = 0; col < ncols; col += scols) {
64 SEG->address(SEG, row, col, &n, &index);
65 SEG->seek(SEG, n, index);
66
67 if ((result = write(SEG->fd, buf, size)) != size) {
68 G_warning("Segment_put_row write error %s", strerror(errno));
69 /* printf("Segment_put_row result = %d. ncols: %d, scols %d,
70 * size: %d, col %d, row: %d, SEG->fd:
71 * %d\n",result,ncols,scols,size,col,row, SEG->fd); */
72 return -1;
73 }
74
75 /* The buf variable is a void pointer and thus points to anything. */
76 /* Therefore, it's size is unknown and thus, it cannot be used for */
77 /* pointer arithmetic (some compilers treat this as an error - SGI */
78 /* MIPSPro compiler for one). Since the read command is reading in */
79 /* "size" bytes, cast the buf variable to char * before incrementing */
80 buf = ((const char *)buf) + size;
81 }
82
83 if ((size = SEG->spill * SEG->len)) {
84 SEG->address(SEG, row, col, &n, &index);
85 SEG->seek(SEG, n, index);
86
87 if (write(SEG->fd, buf, size) != size) {
88 G_warning("Segment_put_row final write error: %s", strerror(errno));
89 return -1;
90 }
91 }
92
93 return 1;
94}
void G_warning(const char *msg,...)
Print a warning message to stderr.
Definition gis/error.c:203
int Segment_put_row(const SEGMENT *SEG, const void *buf, off_t row)
Write row to segment file.
Definition put_row.c:41