2.7 File input/output

Included in the UDI library are interface routines to the Universal File Input/Output (UIO) package, a library of C-language routines which provide a way to handle both binary and ASCII format files.

The UDI - UIO interface provides routines for opening/closing files and reading/writing UDI objects.

 

int udi_open_file(filename, filetype, filemode)
   char *filename, *filemode;
   int filetype;

Where

• SPMquotfilename" is the full pathname of the file to be opened.
• SPMquotfiletype" is one of the following

  UDI_FILE_ASCII"	ASCII-format file
  UDI_FILE_ASCII_N"	ASCII-format file with line numbers
  UDI_FILE_BIN"	binary-format file

• SPMquotfilemode" is one of the following

  SPMquota"	open file for writing at end of file, or create for writing
  w"	open new file for writing
  r"	open existing file for reading

The return value from udi_open_file" is a file number which needs to be passed to the read/write routines. An error will be signalled by UDI if there's a problem opening the file, and may be handled like any other UDI error.

 

int uio_close_file(filenumber)
   int filenumber; /* this should be the value returned from udi_open_file */

There are special routines for opening stdin", SPMquotstdout", and SPMquotstderr".

     

int udi_open_stdin(filetype)
   int filetype;

int udi_open_stdout(filetype)
   int filetype;

int udi_open_stderr(filetype)
   int filetype;

During the initialization process in SPMquotbegin_udi()", stdin", stdout", and SPMquotstderr" are opened with the following file-number variable names and file formats:

Variable name	File format
SPMquotF_stdin"	SPMquotUDI_FILE_BIN"
SPMquotF_stdout"	UDI_FILE_BIN"
SPMquotF_stderr"	SPMquotUDI_FILE_ASCII"

In general, the user only needs to call these special open routines if these default file formats are not acceptable.

There exist four routines for reading/writing UDI objects.

   

int read_object(file, object)
   int file;           /* the file number returned from udi_open */
   UDI_object object;  /* the object which will receive the data */

int read_part_object(file, object, offset, num)
   int file;
   UDI_object object;
   int offset;        /* the element offset into object */
   int num;           /* the number of elements to be read */

Both of these routines return the number of elements read into object".    

void write_object(file, object)
   int file;
   UDI_object object;

void write_part_object(file, object, offset, num)
   int file;
   UDI_object object;
   int offset, num;