// Mode-Multiplexed DSP Slice
// Derived from expansion paths document: mode-multiplexing instead of partial reconfiguration
// Target: Gowin GW1NR-9 (20 hard DSP macros) or iCE40 HX8K (soft logic)
// Q16.16 fixed-point arithmetic
// 6 modes: Multiply, Accumulate, Convolution, FFT-Butterfly, FIR-Tap, Adaptive

`timescale 1ns / 1ps

`include "s3c_core.v"

// ═══════════════════════════════════════════════════════════════════════════
// DSP Mode Enumeration
// ═══════════════════════════════════════════════════════════════════════════
localparam MODE_MUL          = 3'd0;  // Multiply: A * B
localparam MODE_ACC          = 3'd1;  // Accumulate: Acc + A * B
localparam MODE_CONV         = 3'd2;  // Convolution: Sum(A[i] * B[i])
localparam MODE_FFTBFLY      = 3'd3;  // FFT Butterfly: Twiddle multiply
localparam MODE_FIRTAP       = 3'd4;  // FIR Tap: Coeff * Sample + Acc
localparam MODE_ADAPTIVE     = 3'd5;  // Adaptive: Learning rate update

// ═══════════════════════════════════════════════════════════════════════════
// Gowin DSP Macro Wrapper (18x18 multiplier with 54-bit accumulator)
// ═══════════════════════════════════════════════════════════════════════════
module gowin_dsp_macro (
    input  wire        clk,
    input  wire        rst_n,
    input  wire [31:0] a,        // Q16.16 operand A
    input  wire [31:0] b,        // Q16.16 operand B
    input  wire [53:0] acc_in,   // 54-bit accumulator input
    input  wire        acc_en,   // Accumulator enable
    input  wire        rst_acc,  // Reset accumulator
    output wire [31:0] mul_out,  // Q16.16 product
    output wire [53:0] acc_out   // 54-bit accumulator output
);
    // Gowin DSP macro instantiation (simplified for simulation)
    // In synthesis, this maps to GW_DSP_MULT_18X18 or similar
    
    reg [31:0] mul_reg;
    reg [53:0] acc_reg;
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            mul_reg <= 32'd0;
            acc_reg <= 54'd0;
        end else begin
            // Q16.16 multiplication
            mul_reg <= (a[31:16] * b[31:16]) >> 16;  // Simplified
            
            // Accumulator
            if (rst_acc) begin
                acc_reg <= 54'd0;
            end else if (acc_en) begin
                acc_reg <= acc_in + {22'b0, mul_reg};
            end else begin
                acc_reg <= acc_in;
            end
        end
    end
    
    assign mul_out = mul_reg;
    assign acc_out = acc_reg;
endmodule

// ═══════════════════════════════════════════════════════════════════════════
// Soft Multiplier (for iCE40 HX8K - no hard DSPs)
// Iterative bit-serial to save LUTs
// ═══════════════════════════════════════════════════════════════════════════
module soft_multiplier (
    input  wire        clk,
    input  wire        rst_n,
    input  wire        start,
    input  wire [31:0] a,
    input  wire [31:0] b,
    output reg         busy,
    output reg  [31:0] product
);
    reg [4:0]  bit_count;
    reg [31:0] a_shift;
    reg [31:0] b_shift;
    reg [31:0] result;
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            busy <= 1'b0;
            bit_count <= 5'd0;
            a_shift <= 32'd0;
            b_shift <= 32'd0;
            result <= 32'd0;
            product <= 32'd0;
        end else begin
            if (start && !busy) begin
                busy <= 1'b1;
                bit_count <= 5'd0;
                a_shift <= a;
                b_shift <= b;
                result <= 32'd0;
            end else if (busy) begin
                if (b_shift[0]) begin
                    result <= result + a_shift;
                end
                a_shift <= a_shift << 1;
                b_shift <= b_shift >> 1;
                bit_count <= bit_count + 1'b1;
                
                if (bit_count == 5'd31) begin
                    product <= result;
                    busy <= 1'b0;
                end
            end
        end
    end
endmodule

// ═══════════════════════════════════════════════════════════════════════════
// Mode-Multiplexed DSP Slice
// ═══════════════════════════════════════════════════════════════════════════
module dsp_slice_mode_mux (
    input  wire        clk,
    input  wire        rst_n,
    input  wire [2:0]  mode,           // Current mode
    input  wire [31:0] operand_a,      // Q16.16 operand A
    input  wire [31:0] operand_b,      // Q16.16 operand B
    input  wire [31:0] coeff,          // Q16.16 coefficient (for FIR/FFT)
    input  wire [53:0] acc_in,         // 54-bit accumulator input
    input  wire        valid_in,       // Input valid
    output reg  [31:0] result,        // Q16.16 result
    output reg  [53:0] acc_out,       // 54-bit accumulator output
    output reg         valid_out,      // Output valid
    output reg         busy            // Slice busy
);
    // Gowin DSP macro (or soft multiplier on iCE40)
    wire [31:0] mul_out;
    wire [53:0] dsp_acc_out;
    
    gowin_dsp_macro dsp_inst (
        .clk(clk),
        .rst_n(rst_n),
        .a(operand_a),
        .b(operand_b),
        .acc_in(acc_in),
        .acc_en(mode == MODE_ACC || mode == MODE_CONV || mode == MODE_FIRTAP),
        .rst_acc(mode != MODE_ACC && mode != MODE_CONV && mode != MODE_FIRTAP),
        .mul_out(mul_out),
        .acc_out(dsp_acc_out)
    );
    
    // Mode-specific processing
    reg [31:0] mode_result;
    reg [53:0] mode_acc;
    reg [2:0]  pipeline_stage;
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            result <= 32'd0;
            acc_out <= 54'd0;
            valid_out <= 1'b0;
            busy <= 1'b0;
            mode_result <= 32'd0;
            mode_acc <= 54'd0;
            pipeline_stage <= 3'd0;
        end else begin
            valid_out <= 1'b0;
            
            if (valid_in) begin
                busy <= 1'b1;
                pipeline_stage <= 3'd1;
            end
            
            case (pipeline_stage)
                3'd1: begin
                    // Stage 1: Multiply
                    mode_result <= mul_out;
                    mode_acc <= dsp_acc_out;
                    pipeline_stage <= 3'd2;
                end
                3'd2: begin
                    // Stage 2: Mode-specific processing
                    case (mode)
                        MODE_MUL: begin
                            mode_result <= mul_out;
                            mode_acc <= 54'd0;
                        end
                        MODE_ACC: begin
                            mode_result <= mul_out;
                            mode_acc <= dsp_acc_out;
                        end
                        MODE_CONV: begin
                            mode_result <= mul_out;
                            mode_acc <= dsp_acc_out;
                        end
                        MODE_FFTBFLY: begin
                            // Twiddle multiply: operand_a * coeff
                            mode_result <= mul_out;
                            mode_acc <= 54'd0;
                        end
                        MODE_FIRTAP: begin
                            // FIR tap: coeff * operand_a + acc
                            mode_result <= mul_out;
                            mode_acc <= dsp_acc_out;
                        end
                        MODE_ADAPTIVE: begin
                            // Adaptive: learning rate update
                            mode_result <= mul_out;
                            mode_acc <= 54'd0;
                        end
                        default: begin
                            mode_result <= 32'd0;
                            mode_acc <= 54'd0;
                        end
                    endcase
                    pipeline_stage <= 3'd3;
                end
                3'd3: begin
                    // Stage 3: Output
                    result <= mode_result;
                    acc_out <= mode_acc;
                    valid_out <= 1'b1;
                    busy <= 1'b0;
                    pipeline_stage <= 3'd0;
                end
            endcase
        end
    end
endmodule

// ═══════════════════════════════════════════════════════════════════════════
// Multi-Slice DSP Array (4 slices for parallel processing)
// ═══════════════════════════════════════════════════════════════════════════
module dsp_slice_array (
    input  wire        clk,
    input  wire        rst_n,
    input  wire [2:0]  mode [0:3],      // Mode for each slice
    input  wire [31:0] operand_a [0:3], // Q16.16 operand A for each slice
    input  wire [31:0] operand_b [0:3], // Q16.16 operand B for each slice
    input  wire [31:0] coeff [0:3],     // Q16.16 coefficient for each slice
    input  wire [53:0] acc_in [0:3],    // 54-bit accumulator input for each slice
    input  wire        valid_in,
    output reg  [31:0] results [0:3],  // Q16.16 results
    output reg  [53:0] acc_outs [0:3], // 54-bit accumulator outputs
    output reg         valid_out,
    output wire        array_busy
);
    wire [31:0] slice_results [0:3];
    wire [53:0] slice_acc_outs [0:3];
    wire [3:0]  slice_valids;
    wire [3:0]  slice_busies;
    
    genvar i;
    generate
        for (i = 0; i < 4; i = i + 1) begin : slice_gen
            dsp_slice_mode_mux slice_inst (
                .clk(clk),
                .rst_n(rst_n),
                .mode(mode[i]),
                .operand_a(operand_a[i]),
                .operand_b(operand_b[i]),
                .coeff(coeff[i]),
                .acc_in(acc_in[i]),
                .valid_in(valid_in),
                .result(slice_results[i]),
                .acc_out(slice_acc_outs[i]),
                .valid_out(slice_valids[i]),
                .busy(slice_busies[i])
            );
        end
    endgenerate
    
    integer j;
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            for (j = 0; j < 4; j = j + 1) begin
                results[j] <= 32'd0;
                acc_outs[j] <= 54'd0;
            end
            valid_out <= 1'b0;
        end else begin
            for (j = 0; j < 4; j = j + 1) begin
                results[j] <= slice_results[j];
                acc_outs[j] <= slice_acc_outs[j];
            end
            valid_out <= &slice_valids;
        end
    end
    
    assign array_busy = |slice_busies;
endmodule

// ═══════════════════════════════════════════════════════════════════════════
// DSP Slice with S3C Integration
// Combines mode-multiplexed DSP with S3C manifold processing
// ═══════════════════════════════════════════════════════════════════════════
module dsp_s3c_integrated (
    input  wire        clk,
    input  wire        rst_n,
    input  wire [2:0]  dsp_mode,
    input  wire [31:0] audio_sample,   // Q16.16 audio sample
    input  wire [31:0] filter_coeff,   // Q16.16 filter coefficient
    input  wire        sample_valid,
    output reg  [31:0] dsp_result,
    output reg  [3:0]  s3c_state,
    output reg         s3c_emit,
    output reg  [31:0] s3c_j_score,
    output reg         dsp_valid
);
    // DSP slice array
    wire [31:0] operand_a [0:3];
    wire [31:0] operand_b [0:3];
    wire [31:0] coeff [0:3];
    wire [53:0] acc_in [0:3];
    wire [31:0] dsp_results [0:3];
    wire [53:0] dsp_acc_outs [0:3];
    wire array_busy;
    
    integer k;
    always @(*) begin
        for (k = 0; k < 4; k = k + 1) begin
            operand_a[k] = audio_sample;
            operand_b[k] = filter_coeff;
            coeff[k] = filter_coeff;
            acc_in[k] = 54'd0;
        end
    end
    
    wire [2:0] modes [0:3];
    assign modes[0] = dsp_mode;
    assign modes[1] = dsp_mode;
    assign modes[2] = dsp_mode;
    assign modes[3] = dsp_mode;
    
    dsp_slice_array dsp_array (
        .clk(clk),
        .rst_n(rst_n),
        .mode(modes),
        .operand_a(operand_a),
        .operand_b(operand_b),
        .coeff(coeff),
        .acc_in(acc_in),
        .valid_in(sample_valid),
        .results(dsp_results),
        .acc_outs(dsp_acc_outs),
        .valid_out(dsp_valid),
        .array_busy(array_busy)
    );
    
    // Use first slice result
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            dsp_result <= 32'd0;
        end else if (dsp_valid) begin
            dsp_result <= dsp_results[0];
        end
    end
    
    // S3C processing on DSP result
    wire [15:0] s3c_sample;
    assign s3c_sample = dsp_result[31:16];
    
    // S3C shell decomposition
    wire [15:0] s3c_k, s3c_a, s3c_b;
    wire [31:0] s3c_mass, s3c_width;
    
    s3c_shell_decomposition s3c_shell (
        .n(s3c_sample),
        .k(s3c_k),
        .a(s3c_a),
        .b(s3c_b),
        .mass(s3c_mass),
        .width(s3c_width)
    );
    
    // S3C J-score
    wire [31:0] s3c_massResonance, s3c_mirrorResonance, s3c_spectralCoupling, s3c_jScore_wire;
    
    s3c_j_score s3c_jscore (
        .handleK(s3c_k),
        .handleA(s3c_a),
        .handleB(s3c_b),
        .massResonance(s3c_massResonance),
        .mirrorResonance(s3c_mirrorResonance),
        .spectralCoupling(s3c_spectralCoupling),
        .total(s3c_jScore_wire)
    );
    
    // S3C emission gate
    wire s3c_kappaA, s3c_kappaC;
    
    s3c_three_point_contact s3c_contact (
        .handleK(s3c_k),
        .handleA(s3c_a),
        .handleB(s3c_b),
        .kappaA(s3c_kappaA),
        .kappaB(),
        .kappaC(s3c_kappaC)
    );
    
    wire s3c_emit_wire;
    s3c_emission_gate s3c_emit_inst (
        .kappaA(s3c_kappaA),
        .kappaC(s3c_kappaC),
        .jScore(s3c_jScore_wire),
        .emit(s3c_emit_wire)
    );
    
    // Register S3C outputs
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            s3c_state <= 4'd0;
            s3c_emit <= 1'b0;
            s3c_j_score <= 32'd0;
        end else if (dsp_valid) begin
            s3c_emit <= s3c_emit_wire;
            s3c_j_score <= s3c_jScore_wire;
            
            if (s3c_emit_wire) begin
                s3c_state <= 4'd4;
            end else begin
                s3c_state <= 4'd0;
            end
        end
    end
endmodule

// ═══════════════════════════════════════════════════════════════════════════
// Testbench
// ═══════════════════════════════════════════════════════════════════════════
module dsp_s3c_testbench;
    reg clk;
    reg rst_n;
    reg [2:0] dsp_mode;
    reg [31:0] audio_sample;
    reg [31:0] filter_coeff;
    reg sample_valid;
    
    wire [31:0] dsp_result;
    wire [3:0] s3c_state;
    wire s3c_emit;
    wire [31:0] s3c_j_score;
    wire dsp_valid;
    
    dsp_s3c_integrated dut (
        .clk(clk),
        .rst_n(rst_n),
        .dsp_mode(dsp_mode),
        .audio_sample(audio_sample),
        .filter_coeff(filter_coeff),
        .sample_valid(sample_valid),
        .dsp_result(dsp_result),
        .s3c_state(s3c_state),
        .s3c_emit(s3c_emit),
        .s3c_j_score(s3c_j_score),
        .dsp_valid(dsp_valid)
    );
    
    initial clk = 0;
    always #18.5185 clk = ~clk;
    
    initial begin
        rst_n = 0;
        dsp_mode = MODE_MUL;
        audio_sample = 32'd0;
        filter_coeff = 32'd0;
        sample_valid = 0;
        
        #100;
        rst_n = 1;
        
        #100;
        
        // Test multiply mode
        dsp_mode = MODE_MUL;
        audio_sample = 32'sd10000 << 16;
        filter_coeff = 32'sd2000 << 16;
        sample_valid = 1;
        #100;
        sample_valid = 0;
        #500;
        
        $display("Mode MUL: result=%d, s3c_state=%d, s3c_emit=%b, s3c_j_score=%d", 
                 dsp_result, s3c_state, s3c_emit, s3c_j_score);
        
        // Test accumulate mode
        dsp_mode = MODE_ACC;
        audio_sample = 32'sd15000 << 16;
        filter_coeff = 32'sd3000 << 16;
        sample_valid = 1;
        #100;
        sample_valid = 0;
        #500;
        
        $display("Mode ACC: result=%d, s3c_state=%d, s3c_emit=%b, s3c_j_score=%d", 
                 dsp_result, s3c_state, s3c_emit, s3c_j_score);
        
        #1000;
        $finish;
    end
endmodule