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Gray Code Generator - Matlab Script to Generate Verilog Header for Gray Coding

● November 2, 2010 ● Coded in Matlab 
%==============================================================================
%
%                   Gray Code Generator for Verilog
%
%   This script generates a Verilog header (.vh) file which contains a set of
%   of `define directives to establish Gray-coded states for a state machine.
%   The output of this script is intended to be used in conjunction with a
%   Verilog design which uses Gray coding in some application.  For more
%   information on Gray coding, please see 
%   http://mathworld.wolfram.com/GrayCode.html.
%
%   Usage: 
%
%       The bit width of the Gray coded states is set as a script variable.
%       2^bit_width states are generated.  The output filename is also 
%       set as a script variable.
%
%   Author: Tom Chatt
%
%------------------------------------------------------------------------------
% Revision History:
%
%   Original Version        Tom Chatt           11/2/2010
%
%==============================================================================

clear all; clc;

%------------------------------------------------------------------------------

bit_width = 8;  % Bit width of the generated code

% Print the generated code entries to a Verilog defines file?
print_to_v_def_file = true;

output_file = ['gray_code_',num2str(bit_width),'.vh']; % Output file name

% Gray code state name prefix.  State names will be of the form 
% GC<bit_width>B_<state number>.
prefix = ['GC',num2str(bit_width),'B_'];

%--------------Do not edit code below this point-------------------------------

% Generate the code, starting with 1 bit code and looping upward
code = [0; 1];
if bit_width ~= 1
    for i = 2 : bit_width
        code = [zeros(size(code,1), 1), code; ones(size(code,1), 1), flipud(code)]; %#ok<AGROW>
    end
end

% Print out the generated code
fid = fopen(output_file, 'w');

for i = 1 : size(code,1)
   
    macro_name = [prefix, num2str(i)];
    macro_val = [num2str(bit_width),'''', dec2bin(binvec2dec(code(i,:)),bit_width)];
    fprintf(fid, ['ifndef ',macro_name,'\n']);
    fprintf(fid, ['    ','`define ', macro_name, ' ', macro_val, '\n']);
    fprintf(fid, 'endif\n');
    
end

fclose('all');