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#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include "segment.h"
/* bugfix:
* int segment_get_row (SEGMENT *SEG, CELL *buf,int row) */
/*!
* \brief read row from segment file
*
* Transfers data from a segment file, row by row, into memory
* (which can then be written to a regular matrix file). <b>Seg</b> is the
* segment structure that was configured from a call to <i>segment_init.</i>
* <b>Buf</b> will be filled with <i>ncols*len</i> bytes of data
* corresponding to the <b>row</b> in the data matrix.
* Return codes are: 1 if ok; else -1 could not seek or read segment file.
*
* \param seg
* \param buf
* \param row
* \return int
*/
int segment_get_row (SEGMENT *SEG, void *buf,int row)
{
int size;
int ncols;
int scols;
int n, index, col;
ncols = SEG->ncols - SEG->spill ;
scols = SEG->scols ;
size = scols * SEG->len;
for (col = 0; col < ncols; col += scols)
{
segment_address (SEG, row, col, &n, &index) ;
if(segment_seek (SEG, n, index) < 0)
return -1;
if(read (SEG->fd, buf, size) != size)
{
G_warning ("segment_get_row: %s\n",strerror(errno));
return -1;
}
/* The buf variable is a void pointer and thus points to anything. */
/* Therefore, it's size is unknown and thus, it cannot be used for */
/* pointer arithmetic (some compilers treat this as an error - SGI */
/* MIPSPro compiler for one). Since the read command is reading in */
/* "size" bytes, cast the buf variable to char * before incrementing */
buf = ((char *) buf) + size;
}
if ((size = SEG->spill * SEG->len))
{
segment_address (SEG, row, col, &n, &index) ;
if(segment_seek (SEG, n, index) < 0)
return -1;
if(read (SEG->fd, buf, size) != size)
{
G_warning ("segment_get_row: %s\n",strerror(errno));
return -1;
}
}
return 1;
}
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