Files

Slide 13 of 53

Notes:

VHDL defines the file object and includes some basic file IO procedures implicitly after a file type is defined. A file type must be defined for each VHDL type that is to be input from or output to a file.

Example:

TYPE bit_file IS FILE of bit;

In VHDL87, there are no routines to open or close a file, so both the mode of the file and its name must be specified in the file declaration. The mode defaults to read if none is specified.

Examples:

FILE in_file:bit_file IS “my_file.dat” -- opens a file for reading

FILE out_file:bit_file IS OUT “my_other_file.dat”; -- opens a file for writing

In VHDL93, a file can be named and opened in the declaration:

FILE in_file:bit_file OPEN READ_MODE IS “my_file.dat”; -- opens a file for reading

Or simply declared (and named and opened later):

FILE out_file:bit_file;