SyndromeParallel.bsv

//----------------------------------------------------------------------//
// The MIT License
//
// Copyright (c) 2008 Abhinav Agarwal, Alfred Man Cheuk Ng
// Contact: abhiag@gmail.com
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
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// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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//----------------------------------------------------------------------//

import FIFO::*;
import GFArith::*;
import GFTypes::*;
import Vector::*;

// ---------------------------------------------------------
// Reed-Solomon Syndrome calculator interface
// ---------------------------------------------------------
interface ISyndrome;
    method Action                         n_in(Byte n_new); // dynamic n (shorten/punctured codeword)
    method Action                         r_in(Byte datum);

    method ActionValue#(Syndrome#(TwoT))  s_out();
endinterface

// ---------------------------------------------------------
// Reed-Solomon Syndrome calculation module
// ---------------------------------------------------------
(* synthesize *)
module mkSyndromeParallel(ISyndrome);

    Reg#(Syndrome#(TwoT))   syndrome       <- mkReg(replicate(0));
    FIFO#(Byte)             n_q            <- mkSizedFIFO(2);
    Reg#(Byte)              i              <- mkReg(0);
    Reg#(Byte)              block_number   <- mkReg(1);

    let n = n_q.first();

    // ------------------------------------------------
    method Action r_in (Byte datum) if (i < n);
        $display ("  [syndrome %d]  r_in (%d): %d", block_number, i, datum);
        Syndrome#(TwoT) syndrome_temp = replicate(0);

        for (Byte x = 0; x < fromInteger(valueOf(TwoT)); x = x + 1) begin
            syndrome_temp[x] = times_alpha_n(syndrome[x], x + 1);
            syndrome_temp[x] = gf_add(syndrome_temp[x], datum);
        end

        syndrome <= syndrome_temp;
        i <= i + 1;
    endmethod

    // ------------------------------------------------
    method ActionValue#(Syndrome#(TwoT)) s_out() if (i == n);
        $display ("  [syndrome %d]  s_out", block_number);

        // consider the next n
        n_q.deq();
        // reset state
        i <= 0;
        syndrome <= replicate(0);
        // incr block_numer (just for bookkeeping)
        block_number <= block_number + 1;
        return syndrome;
    endmethod

    // ------------------------------------------------
    method Action n_in (Byte n_new);
        $display ("  [syndrome %d]  n_in : %d", block_number, n_new);
        n_q.enq(n_new);
    endmethod
endmodule