1. Introduction

mprfgen is a multi-port register file generator. It can either infer storage or instantiate block-RAM embedded memories for the Xilinx Spartan-3, Virtex-4, Virtex-5 FPGAs or newer.

The generated memories are initialized to ZEROs. Also, when using RAM inference, the following compilation/elaboration order should be used:

1. util_functions_pkg.vhd
2. regfile_core.vhd
3. <your-generated-file>.vhd

Please, note that the default read mode option (read-async) will generate distributed RAM. For block RAM, use read-first, write-first or read-through, instead.

2. File listing

The mprfgen distribution includes the files listed in the following table. Files and/or directories denoted by a capital S are only available in source releases of mprfgen.

/mprfgen	Top-level directory
S build.sh env.sh	Automated build script. Script for setting up the environment.
/bin/lin	Linux executable directory
mprfgen.exe	Static executable for Linux platforms.
/bin/win	Windows executable directory
mprfgen.exe	Static executable for Windows platforms.
/doc	Documentation directory
AUTHORS LICENSE README README.html README.pdf VERSION	List of authors. End-user license agreement. This file. HTML version of README. PDF version of README. Current version of mprfgen.
/sim	Directory for simulation files
change-generics.pl ghdl.mk	Perl script for adapting the testbench template. Makefile for running a GHDL (http://ghdl.free.fr) simulation.
ghdl.sh regfile_tb_tmpl.vhd	Bash script for running a GHDL simulation. Generic testbench for simulative testing of generated multi-port register files.
S /src	Source code directory
S Makefile S mprfgen.c	Makefile for generating the mprfgen executable. The source code for the application.
/test	Directory for testing mprfgen
regfile.vhd	Generic model of a multi-port register file (for reference).
regfile_core.vhd	Single-read, single-write port memory model used by the generated memories (mandatory for inferred memory).
test[1-5].vhd test.sh util_functions_pkg.vhd	Sample files generated as shown in section 5. Generate the samples discussed in section 5. A VHDL package providing some utility functions.

3. mprfgen setup

For using mprfgen, this distribution comes with ready-made native executables for Windows and Linux, which can be found in the corresponding /bin/exedir directory, where exedir is lin for Linux or win for Windows.

In order to build mprfgen from source on your platform, just run the build.sh bash script from the command prompt. First, change to the appropriate directory, for instance:

assuming mprfgen was installed inside /home/user and finally run the script:

4. mprfgen usage

The mprfgen program can be invoked with several options (see complete options listing below). The usual tasks that can be accomplished with mprfgen are:

• infer a multi-port register file for NWP write ports and NRP read ports
• instantiate a multi-port register file for Xilinx FPGAs

mprfgen can be invoked as:

options` is one or more of the following:

-h

Print this help.

-infer

Use generic RAM storage that can be inferred as block RAM(s).

-<read-mode>

Read mode supported by the generated RAM. Valid options: (read-async, read-first, write-first, read-through). read-through cannot be used for block RAM instantiation. Default is read-async.

-nwp <num>

Number of write ports for the register file.

-nrp <num>

Number of read ports for the register file.

-bw <num>

Bitwidth for each memory entry.

-nregs <num>

Memory size (number of words).

5. Running some tests

Here follow some simple usage examples of mprfgen assuming the user is at the /mprfgen/test directory and is running Linux.

1. Generate a 3-read, 2-write port generic register file.

2. Generate a 1-read, 1-write port 32x2048 memory.

3. Generate a 2-read, 1-write port LUT-based register file.

4. Generate a 2-read, 1-write port block RAM register file with direct instantiation.

5. Generate a 2-read, 2-write port block RAM register file with direct instantiation.

It is better to set up the MPRFGEN_BIN_PATH environmental variable using

or

The user can add the mprfgen binaries directory to the PATH, e.g.:

in order to directly use mprfgen invocations.

Windows users are prompted to set the MPRFGEN_BIN_PATH environmental variable to an appropriate value. An example is C:\mprfgen\bin\win, assuming that mprfgen has been installed in C:.

6. Simulation

The generated multi-port register files can be simulated with the supplied files found in the /sim subdirectory, given that they have been generated with the -infer option enabled. This means that the provided test4.vhd cannot be simulated, while test1.vhd, test2.vhd, test3.vhd, and test5.vhd that don't require proprietary Xilinx libraries can.

For running the GHDL simulation of a generated file, e.g. test1.vhd, change directory to the /sim subdirectory:

assuming MPRFGEN_HOME is the directory where the top-level /mprfgen is found.

Then, the corresponding shell script is executed:

The simulation produces a VCD (waveform) dump named test1.vcd which can be inspected for simulation correctness.

For the stimulus data used in the testbench, it is assumed that the following inequations hold:

• NWP * AW >= 4
• NRP * AW >= 4
• DW >= 8

7. Prerequisities

• Standard UNIX-based tools (tested with gcc-3.4.4 on cygwin/x86, gcc-3.4.5 on mingw/x86, gcc-4.1.2 on Fedora 8 and gcc-4.6.1 on Ubuntu 11.10).

  • make
  • bash (shell)
  • perl

  For rebuilding on Windows, the Cygwin (http://sources.redhat.com/cygwin) is a popular solution, since it provides a near-complete POSIX environment.

• GHDL simulator (http://ghdl.free.fr) for Windows or Linux.

  The latest GHDL distribution (0.29.1, Windows version) also installs GTKwave on Windows.