Title

Fixed and Floating point packages

-- David Bishop - 2016-04-29

Comments

VHDL-2008 Support Library

These packages were designed as a bridge between VHDL-93 and VHDL-2008. I replicated as many of the new functions as possible. Note that all of these packages are design to be synthesizable in VHDL-93. So, as long as you stick to the subsets defined in the "README" files for the various vendors you should be able to take your code through the entire flow.

VHDL-2008 is finally getting some traction. &nbsp What started out as just a fixed and floating point package got merged into the VHDL LRM. On this page you will find definitions of the functions available in the VHDL-2008 libraries. You will also find VHDL-93 compatible code for those that do not yet have access to VHDL-2008 compilers.

There is a Fixed Point user's guide and a Floating Point user's guide. Please check the Fixed and floating point FAQ (NEW!) if you have any quesiton.

The VHDL-2008 packages will eventually be included in your vendor's environment. In some cases I have found that they may be encrypted due to IEEE rules. The packages available on this page are NOT the released packages, but VHDL-93 versions of those packages, which I published BEFORE the release of the LRM. They are free of copyright restrictions, and may be used for whatever purpose is needed.

VHDL-93 versions of the VHDL-2008 packages

• Additions to std.standard standard_additions_c.vhdl ( user's guide)
• New package std.env env_c.vhdl
• Additions to std.textio standard_textio_additions_c.vhdl ( user's guide)
• Additions to ieee.std_logic_1164 std_logic_1164_additions.vhdl ( user's guide)
• Additions to ieee.numeric_std numeric_std_additions.vhdl ( user's guide)
• New package numeric_std_unsigned numeric_std_unsigned_c.vhdl ( user's guide)
• New package fixed_float_types fixed_float_types_c.vhdl
• New package fixed_pkg fixed_pkg_c.vhdl ( Fixed Point user's guide)
• New package float_pkg float_pkg_c.vhdl ( Floating Point user's guide)
• ZIP file of all the packages (updated 09/2010)

I use this code in most of my designs. Many times I find that I have to modify the code slightly in some tools, so I made this list. Included in the "source code" section for each tool is source code specifically debugged for that particluar tool. Click on the "documentation" link to see what changes I had to make, and how to use this code in the specific tool.

Vendor	Zip file	Notes
Altera	Source code	Documentation
Cadence ncvhdl	Source code	Documentation
Cadence RC (new)	Source code	Documentation
Modeltech	Source code	Documentation
Synopsys	Source code	Documentation
Synplicity	Source code	Documentation
Xilinx 11.1	Source code	Documentation
Xilinx 9.1	Source code (old)	Documentation
VCS	Source code	Documentation
Spectrum 2009a	Source code	Documentation
Do do:Aldec

Some helpful code to go with these packages:

• fixed_noresize.vhdl Similar to "fixed_pkg", however this version uses the same rules that numeric_std does for the size of the result. This is done by calling the funciton in "fixed_pkg" and resizing the result.
• float_noround_pkg.vhdl Similar to "float_pkg", however this version turns off all of the IEEE rounding and overflow, and defaults to a 26 bit floating point number. This package saves off 1/3 of the logic needed for full 32 bit floating point.
• fixed_synth.vhdl Synthesis testcase for the fixed point package. test_fixed_synth.vhdl Testbench for the fixed point synthesis testcase.
• float_synth.vhdl Synthesis testcase for the floating point package. test_float_synth.vhdl testbench for the floating point synthesis package
• Testbenches to verify an implimentation of VHDL-2008.
• Matrix Math package for type REAL which has a user guide (Done in conjunction with IEEE 1076.1 VHDL-AMS)

Need some help with this code? Drop me an e-mail, maybe I can help.
David W. Bishop dbishopx@gmailNOSPAM.org.