// Spectral Encoder - Implements spectral encoding theory from Signal Theory Compendium
// Based on Semantics/Spectrum.lean
//
// Core concepts:
// - Spectral signature: 8-bin Q16.16 amplitude vector
// - Erdős-Hooley constant: δ ≈ 0.08607 (5643/65536)
// - Spectral overlap: inner product between signatures
// - Piecewise eigenvector merge: superposition with saturation

/* verilator lint_off UNUSEDSIGNAL */
/* verilator lint_off UNUSEDPARAM */
/* verilator lint_off WIDTHEXPAND */

module spectral_encoder (
    input wire clk,
    input wire rst_n,
    input wire [7:0]  data_in,      // Input byte
    input wire        data_valid,
    input wire [2:0]  event_type,   // 0=A, 1=T, 2=G, 3=C
    output reg [15:0] bin0,
    output reg [15:0] bin1,
    output reg [15:0] bin2,
    output reg [15:0] bin3,
    output reg [15:0] bin4,
    output reg [15:0] bin5,
    output reg [15:0] bin6,
    output reg [15:0] bin7,
    output reg        spectral_valid
);

    // Erdős-Hooley constant: δ ≈ 0.08607 (5643/65536)
    localparam ERDOS_HOOLEY = 16'd5643;

    // Spectral signatures for genetic events (A, T, G, C)
    // Each event maps to a unique spectral peak position
    // Event A: bin 0 = 0x7FFF
    // Event T: bin 1 = 0x7FFF
    // Event G: bin 2 = 0x7FFF
    // Event C: bin 3 = 0x7FFF

    // Spectral overlap calculation (inner product)
    function [15:0] spectral_overlap;
        input [15:0] a0, a1, a2, a3, a4, a5, a6, a7;
        input [15:0] b0, b1, b2, b3, b4, b5, b6, b7;
        reg [31:0] acc;
        begin
            acc = ((a0 * b0) >>> 16) + ((a1 * b1) >>> 16) +
                  ((a2 * b2) >>> 16) + ((a3 * b3) >>> 16) +
                  ((a4 * b4) >>> 16) + ((a5 * b5) >>> 16) +
                  ((a6 * b6) >>> 16) + ((a7 * b7) >>> 16);
            spectral_overlap = acc[15:0];
        end
    endfunction

    // Piecewise eigenvector merge with saturation
    function [15:0] piecewise_merge;
        input [15:0] a;
        input [15:0] b;
        reg [16:0] sum;
        begin
            sum = {1'b0, a} + {1'b0, b};
            if (sum > 17'h07FFF)
                piecewise_merge = 16'h7FFF;  // Saturation at 1.0
            else
                piecewise_merge = sum[15:0];
        end
    endfunction

    // Verify spectral gap (no two active peaks adjacent)
    // Simplified: just check individual bins for this demo

    // Spectral signature accumulation
    reg [15:0] acc0, acc1, acc2, acc3, acc4, acc5, acc6, acc7;

    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            spectral_valid <= 1'b0;
            acc0 <= 16'h0000;
            acc1 <= 16'h0000;
            acc2 <= 16'h0000;
            acc3 <= 16'h0000;
            acc4 <= 16'h0000;
            acc5 <= 16'h0000;
            acc6 <= 16'h0000;
            acc7 <= 16'h0000;
        end else begin
            if (data_valid) begin
                // Select spectral signature based on event type
                case (event_type)
                    3'd0: begin  // A: bin 0 = 0x7FFF
                        acc0 <= piecewise_merge(acc0, 16'h7FFF);
                    end
                    3'd1: begin  // T: bin 1 = 0x7FFF
                        acc1 <= piecewise_merge(acc1, 16'h7FFF);
                    end
                    3'd2: begin  // G: bin 2 = 0x7FFF
                        acc2 <= piecewise_merge(acc2, 16'h7FFF);
                    end
                    3'd3: begin  // C: bin 3 = 0x7FFF
                        acc3 <= piecewise_merge(acc3, 16'h7FFF);
                    end
                    default: begin
                        // No change
                    end
                endcase

                // Output accumulated bins
                bin0 <= acc0;
                bin1 <= acc1;
                bin2 <= acc2;
                bin3 <= acc3;
                bin4 <= acc4;
                bin5 <= acc5;
                bin6 <= acc6;
                bin7 <= acc7;
                spectral_valid <= 1'b1;
            end else begin
                spectral_valid <= 1'b0;
            end
        end
    end

endmodule