And it's officially supported in the 2008 standard.
Try turning on the VHDL-2008 switch in your simulator.
If hread and hwrite work without the package reference to
std_logic_textio, then these new features has been implemented.
It works in a couple of the simulators I have tried it.
In the 2008 standard, these functions were upgraded (now handle
parameters that are not a multiple of 4 bits for hexadecimal or
3 bits for octal) and were moved to std_logic_1164. The package
std_logic_textio still exists for backward compatibility.
It has aliases to the functions in std_logic_1164 (to allow
selected name references to the package to still work).
If your simulator does not support VHDL-2008 textio yet,
use std_logic_textio, but avoid selected name references
(such as ieee.std_logic_textio.hwrite) to the subprograms in
the package. This way when you have VHDL-2008 support, your
design will work with or without the reference to
std_logic_textio.
Cheers,
Jim
SynthWorks VHDL Training
www.SynthWorks.com