HP 3000 Manuals

Accessing Files Programmer's Guide

Reading From a Magnetic Tape File 

Example 9-4 is an HP Pascal/iX code segment that reads records
sequentially from an unlabeled magnetic tape file (indicated by variable
tape_file_num) and uses FWRITE to write them to a disk file (indicated by
variable disk_file_num).  The operation is performed in a loop.  The loop
ends when the FREAD intrinsic encounters an EOF marker on the tape
(indicating the end of the tape file).

Example 9-4.  Reading From a Magnetic Tape File 

     procedure copy_tape_to_disk_file;

     var
        record          : packed array [1..30] of char; {declare record         }
        end_of_file     : boolean;                      {declare exit condition }
        record_length   : shortint;                     {size of record read    }
        length          : shortint;                     {declare parameter      }
        control_code    : 0..65535;                     {declare parameter      }

     begin
        end_of_file := false;                          {initialize exit condition}
        control_code := 0;                             {initialize to default    }
        length := -80;                                 {size of record to be copied}

        repeat                                         {loop until exit condition}

           record_length := FREAD (tape_file_num, record, length);
           if ccode = ccl then
              handle_file_error (tape_file, 3)
           else
              if ccode = ccg then                {FREAD returns ccg if EOF     }
              end_of_file := true                {exit condition encountered   }
              else
                begin
                   FWRITE( disk_file_num,        {identity returned by HPFOPEN }
                           record,               {read from tape_file_num      }
                           record_length,        {actual size of record        }
                           control_code          {default                      }
                         );
                   if ccode <> cce then         {check condition code for error}
                   handle_file_error (disk_file, 5);
                end

           entil end_of_file;
     end;                                                  {end procedure      }

If an error is encountered by either FREAD or FWRITE, procedure
handle_file_error is invoked.  For more information about FREAD
intrinsic parameters, refer to the MPE/iX Intrinsics Reference Manual 
(32650-90028).  For more information about the FWRITE intrinsic, refer to
chapter 8, "Writing to a File".  In appendix A, "HP Pascal/iX Program
Examples", example A-1 uses a similar procedure to copy records from a
tape file to a disk file.

MPE/iX 5.0 Documentation