GRASS GIS 8 Programmer's Manual 8.2.0(2022)-exported
put_row.c
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1
2/**
3 * \file lib/segment/put_row.c
4 *
5 * \brief Write segment row routines.
6 *
7 * This program is free software under the GNU General Public License
8 * (>=v2). Read the file COPYING that comes with GRASS for details.
9 *
10 * \author GRASS GIS Development Team
11 *
12 * \date 2005-2018
13 */
14
15#include <stdio.h>
16#include <string.h>
17#include <errno.h>
18#include <unistd.h>
19#include <grass/gis.h>
20#include "local_proto.h"
21
22
23/* buf is CELL * WRAT code */
24/* int Segment_put_row (SEGMENT *SEG, CELL *buf,int row) */
25
26
27/**
28 * \brief Write row to segment file.
29 *
30 * Transfers non-segmented matrix data, row by row, into a segment
31 * file. <b>seg</b> is the segment structure that was configured from a
32 * call to <i>Segment_init()</i>. <b>buf</b> should contain
33 * <em>ncols*len</em> bytes of data to be transferred to the segment
34 * file. <b>row</b> specifies the row from the data matrix being
35 * transferred.
36 *
37 * \param[in,out] SEG segment
38 * \param[in] buf data to write to segment
39 * \param[in] row
40 * \return 1 if successful
41 * \return -1 if unable to seek or write segment file
42 */
43
44int Segment_put_row(const SEGMENT * SEG, const void *buf, off_t row)
45{
46 int size;
47 off_t ncols;
48 int scols;
49 int n, index;
50 int result;
51 off_t col;
52
53 if (SEG->cache) {
54 memcpy(SEG->cache + ((size_t)row * SEG->ncols) * SEG->len, buf, SEG->len * SEG->ncols);
55
56 return 1;
57 }
58
59 ncols = SEG->ncols - SEG->spill;
60 scols = SEG->scols;
61 size = scols * SEG->len;
62 /* printf("Segment_put_row ncols: %d, scols %d, size: %d, col %d, row: %d, SEG->fd: %d\n",ncols,scols,size,col,row, SEG->fd); */
63
64 for (col = 0; col < ncols; col += scols) {
65 SEG->address(SEG, row, col, &n, &index);
66 SEG->seek(SEG, n, index);
67
68 if ((result = write(SEG->fd, buf, size)) != size) {
69 G_warning("Segment_put_row write error %s", strerror(errno));
70 /* printf("Segment_put_row result = %d. ncols: %d, scols %d, size: %d, col %d, row: %d, SEG->fd: %d\n",result,ncols,scols,size,col,row, SEG->fd); */
71 return -1;
72 }
73
74 /* The buf variable is a void pointer and thus points to anything. */
75 /* Therefore, it's size is unknown and thus, it cannot be used for */
76 /* pointer arithmetic (some compilers treat this as an error - SGI */
77 /* MIPSPro compiler for one). Since the read command is reading in */
78 /* "size" bytes, cast the buf variable to char * before incrementing */
79 buf = ((const char *)buf) + size;
80 }
81
82 if ((size = SEG->spill * SEG->len)) {
83 SEG->address(SEG, row, col, &n, &index);
84 SEG->seek(SEG, n, index);
85
86 if (write(SEG->fd, buf, size) != size) {
87 G_warning("Segment_put_row final write error: %s",
88 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:204
int Segment_put_row(const SEGMENT *SEG, const void *buf, off_t row)
Write row to segment file.
Definition: put_row.c:44