BLOCKREAD              Hi Speed Read of Untyped File                 pp 114

 Syntax:  BlockRead (FileVar,Var,Blocks,Result) ;

 Type:    Untyped File

 Form:    Procedure

 Purpose: High speed read of FileVar, which is an Untyped file.

          Var is any variable that holds the data to transfer.

          Blocks is an integer expression defining the number of
          128 byte blocks to be transferred from the variable to disk.

          Result is an optional parameter that returns the actual
          number of 128 byte records transferred.

          The transfer starts with the first byte occupied by the variable
          Var.   The file pointer is advanced by (Recs x 128) bytes.
          The programmer must insure that the variable, Var, occupies
          enough space to accomodate the entire data transfer.

          A file to be operated on by BlockWrite must first be prepared by
          ASSIGN, REWRITE, or RESET.  The standard functions EOF, FILEPOS,
          and FILESIZE function the same as with typed files.

          SEEK uses a component size of 128 bytes.


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 Program  FileCopy ;         { Expanded for clarity }
   Const
     Blocks     = 128                                   ; { 128 blocks      }
     BufSize    = 128                                   ; { 128 byte buffer }
     SourceName = 'INPUT.FIL'                           ; { Source          }
     DestName   = 'OUTPUT.FIL'                          ; { Destination     }

   Var
     Source     : File                                  ; { Untyped file    }
     Dest       : File                                  ; { Untyped file    }
     Buffer     : Array[1..Blocks, 1..BufSize] Of Byte ;
     RecsRead   : Integer ;

   Begin
     Assign (Source, SourceName)                        ; { Name to handle  }
     Reset  (Source)                                    ; { Open for R/W    }
     Assign (Dest, DestName)                            ; { Name to handle  }
     ReWrite(Dest)                                      ; { Open and clear  }
     Repeat
       BlockRead  (Source, Buffer, BufSize, RecsRead)   ; { Source to bfr   }
       BlockWrite (Dest, Buffer, RecsRead)              ; { Bfr to Dest     }
       Until RecsRead = 0                               ; { Empty the bfr   }
     Close (Source)                                     ;
     Close (Dest)                                       ;
     End.