VXopen, VXclose, − VisionX File access functions

VisXfile_t *VXopen(fname, mode);
int  mode;
char *fname;
void VXclose(vfile);
VisXfile_t *vfile;

VXopen performs the file opening function for VisionX files; similar to the UNIX open system cal for UNIX files. The argument mode may be zero for opening a file for reading and 1 for opening a file for writing. If the file name argument fname is a null string then standard input or standard output are used as specified by the mode. VXopen allocates and returns a pointer to a VisionX file structure (VisXfile_t). This structure is used by other VisionX file operations.

When the mode is set to zero, VXopen opens a file for reading, it checks that the file is a correctly structured VisionX file. It will also automatically organize the reformatting of various different file formats including most popular compression schemes. Note, when VXopen returns some of the specified file has been read. Various global elements, such as the file history, are attached to the VisXfile structure and may be accessed by other VisionX file-i/o functions such as VXread or VXreadframe.

When the mode is set to one, VXopen opens the file for writing (and creates it if it does not exist) and sets up the VisionX file structure for that file. It does not actually write anything to the file, the first call to a VisionX file write function such as VXwrite or VXwriteframe will write global information from the file structure to the file. If the file is not to be used for VisionX structured information then the file structure element .fd contains the file descriptor and it may be used by other conventional UNIX utilities to write data to the file.

VXclose Closes a file that has been opened by VXopen. It should be called once all the data for a file has been read or written.

open(2), VXread(3)

A. P. Reeves