Here's the file structure and Verilog source code for a 512-core RISC-V based MIPS eVocore P8700 system:

```
evocore_p8700/
├── core/
│   ├── rv32i_core.v
│   ├── rv32i_alu.v
│   ├── rv32i_ctrl.v
│   ├── rv32i_regfile.v
│   ├── rv32i_pc.v
│   └── rv32i_fetch_decode.v
├── interconnect/
│   ├── crossbar.v
│   ├── router.v
│   └── network_interface.v
├── memory/
│   ├── icache.v
│   ├── dcache.v
│   └── memory_controller.v
├── system/
│   ├── evocore_top.v
│   ├── core_manager.v
│   └── system_ctrl.v
└── testbench/
    ├── tb_evocore.v
    └── tb_core.v
```

### Core files:

**core/rv32i_core.v**
```verilog
module rv32i_core (
    input  wire clk,
    input  wire rst_n,
    input  wire [31:0] instruction,
    input  wire pc_en,
    output reg [31:0] pc_out,
    output reg [31:0] alu_result,
    output reg write_enable
);

    // Control signals
    reg [4:0] rd;
    reg [4:0] rs1;
    reg [4:0] rs2;
    reg [6:0] opcode;
    reg [2:0] funct3;
    reg [6:0] funct7;
    
    // ALU signals
    wire [31:0] alu_input_a;
    wire [31:0] alu_input_b;
    wire [31:0] alu_out;
    wire alu_zero;
    
    // Register file signals
    reg [31:0] regfile_out1;
    reg [31:0] regfile_out2;
    
    // PC logic
    wire [31:0] next_pc;
    reg [31:0] pc_reg;
    
    // Control unit
    rv32i_ctrl ctrl_unit (
        .instruction(instruction),
        .opcode(opcode),
        .funct3(funct3),
        .funct7(funct7),
        .pc_en(pc_en)
    );
    
    // Instruction decode
    assign rd = instruction[11:7];
    assign rs1 = instruction[19:15];
    assign rs2 = instruction[24:20];
    assign opcode = instruction[6:0];
    assign funct3 = instruction[14:12];
    assign funct7 = instruction[31:25];
    
    // PC unit
    rv32i_pc pc_unit (
        .clk(clk),
        .rst_n(rst_n),
        .pc_in(pc_reg),
        .next_pc(next_pc),
        .pc_out(pc_out)
    );
    
    // ALU unit
    rv32i_alu alu_unit (
        .a(alu_input_a),
        .b(alu_input_b),
        .alu_op(opcode),
        .funct3(funct3),
        .funct7(funct7),
        .result(alu_out),
        .zero(alu_zero)
    );
    
    // Register file
    rv32i_regfile regfile (
        .clk(clk),
        .rst_n(rst_n),
        .write_enable(write_enable),
        .rd(rd),
        .rs1(rs1),
        .rs2(rs2),
        .regfile_out1(regfile_out1),
        .regfile_out2(regfile_out2)
    );
    
    // Connect inputs to ALU
    assign alu_input_a = (opcode == 7'b1100011) ? pc_reg : regfile_out1;
    assign alu_input_b = regfile_out2;
    
    // Write back logic
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            write_enable <= 1'b0;
            alu_result <= 32'h0;
        end else begin
            write_enable <= (opcode == 7'b1101111) ? 1'b0 : 1'b1;
            alu_result <= alu_out;
        end
    end

endmodule
```

**core/rv32i_alu.v**
```verilog
module rv32i_alu (
    input [31:0] a,
    input [31:0] b,
    input [6:0] alu_op,
    input [2:0] funct3,
    input [6:0] funct7,
    output reg [31:0] result,
    output reg zero
);

    wire [31:0] add_result;
    wire [31:0] sub_result;
    wire [31:0] and_result;
    wire [31:0] or_result;
    wire [31:0] xor_result;
    wire [31:0] slt_result;
    wire [31:0] sll_result;
    wire [31:0] srl_result;
    wire [31:0] sra_result;
    
    wire [31:0] shift_amount;
    
    // ALU operations
    assign add_result = a + b;
    assign sub_result = a - b;
    assign and_result = a & b;
    assign or_result = a | b;
    assign xor_result = a ^ b;
    
    // SLT operation (signed)
    assign slt_result = (a < b) ? 32'h1 : 32'h0;
    
    // Shift operations
    assign shift_amount = b[4:0];
    assign sll_result = a << shift_amount;
    assign srl_result = a >> shift_amount;
    assign sra_result = a >>> shift_amount; // Arithmetic right shift
    
    always @(*) begin
        case (alu_op)
            7'b1100011: result = (funct3 == 3'b010) ? sub_result : add_result;
            7'b1100111: result = sll_result;
            7'b1101011: result = (funct3 == 3'b100) ? xor_result : 
                                   (funct3 == 3'b110) ? or_result :
                                   (funct3 == 3'b111) ? and_result : add_result;
            7'b1101111: result = add_result;
            default: result = add_result;
        endcase
    end
    
    assign zero = (result == 32'h0);

endmodule
```

**core/rv32i_ctrl.v**
```verilog
module rv32i_ctrl (
    input [31:0] instruction,
    output reg [6:0] opcode,
    output reg [2:0] funct3,
    output reg [6:0] funct7,
    input pc_en
);

    always @(*) begin
        opcode = instruction[6:0];
        funct3 = instruction[14:12];
        funct7 = instruction[31:25];
    end

endmodule
```

**core/rv32i_regfile.v**
```verilog
module rv32i_regfile (
    input clk,
    input rst_n,
    input write_enable,
    input [4:0] rd,
    input [4:0] rs1,
    input [4:0] rs2,
    output reg [31:0] regfile_out1,
    output reg [31:0] regfile_out2
);

    // 32 registers of 32 bits each
    reg [31:0] registers [0:31];
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            registers[0] <= 32'h0; // Zero register is always 0
        end else if (write_enable && rd != 5'b0) begin
            registers[rd] <= regfile_out1;
        end
    end
    
    // Read from registers
    always @(*) begin
        regfile_out1 = registers[rs1];
        regfile_out2 = registers[rs2];
    end

endmodule
```

**core/rv32i_pc.v**
```verilog
module rv32i_pc (
    input clk,
    input rst_n,
    input [31:0] pc_in,
    output [31:0] next_pc,
    output reg [31:0] pc_out
);

    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            pc_out <= 32'h0;
        end else begin
            pc_out <= next_pc;
        end
    end
    
    assign next_pc = pc_in + 4;

endmodule
```

**interconnect/crossbar.v**
```verilog
module crossbar (
    input [511:0] inputs,
    input [8:0] addr,
    output reg [31:0] output_data
);

    // Simple crossbar implementation for 512 cores
    wire [31:0] core_outputs [0:511];
    
    // Each core connects to its own address space
    genvar i;
    for (i = 0; i < 512; i = i + 1) begin : g_core
        assign core_outputs[i] = inputs[(i*32)+31:(i*32)];
    end
    
    // Address decode logic
    always @(*) begin
        output_data = core_outputs[addr];
    end

endmodule
```

**interconnect/router.v**
```verilog
module router (
    input clk,
    input rst_n,
    input [31:0] data_in,
    input [8:0] dest_addr,
    input [8:0] src_addr,
    output reg [31:0] data_out,
    output reg [8:0] next_addr
);

    // Simple routing table (simplified for example)
    always @(*) begin
        if (dest_addr < 256) begin
            next_addr = dest_addr + 256; // Route to second half
        end else begin
            next_addr = dest_addr - 256;
        end
    end
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            data_out <= 32'h0;
        end else begin
            data_out <= data_in;
        end
    end

endmodule
```

**memory/icache.v**
```verilog
module icache (
    input clk,
    input rst_n,
    input [31:0] addr,
    output reg [31:0] instruction,
    input valid_addr
);

    // Simple instruction cache (256 entries)
    reg [31:0] cache [0:255];
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            instruction <= 32'h0;
        end else if (valid_addr) begin
            instruction <= cache[addr[7:0]];
        end
    end

endmodule
```

**memory/dcache.v**
```verilog
module dcache (
    input clk,
    input rst_n,
    input [31:0] addr,
    input [31:0] data_in,
    input write_enable,
    output reg [31:0] data_out,
    input valid_addr
);

    // Simple data cache (256 entries)
    reg [31:0] cache [0:255];
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            data_out <= 32'h0;
        end else if (valid_addr) begin
            if (write_enable) begin
                cache[addr[7:0]] <= data_in;
            end
            data_out <= cache[addr[7:0]];
        end
    end

endmodule
```

**system/evocore_top.v**
```verilog
module evocore_top (
    input clk,
    input rst_n
);

    // 512 core system
    wire [31:0] core_outputs [0:511];
    wire [31:0] interconnect_outputs [0:511];
    
    // Clock and reset distribution
    wire core_clk;
    wire core_rst_n;
    
    // Clock generation
    assign core_clk = clk;
    assign core_rst_n = rst_n;
    
    // Core instantiation
    genvar i;
    for (i = 0; i < 512; i = i + 1) begin : g_core
        rv32i_core core (
            .clk(core_clk),
            .rst_n(core_rst_n),
            .instruction(32'h0), // Will be connected to interconnect
            .pc_en(1'b1),
            .pc_out(),
            .alu_result(core_outputs[i]),
            .write_enable()
        );
    end
    
    // Interconnect network
    crossbar crossbar_inst (
        .inputs({core_outputs}),
        .addr(9'h0),
        .output_data(interconnect_outputs[0])
    );
    
    // Memory controller
    memory_controller mem_ctrl (
        .clk(clk),
        .rst_n(rst_n),
        .input_data(interconnect_outputs),
        .output_data(),
        .memory_addr()
    );

endmodule
```

**system/core_manager.v**
```verilog
module core_manager (
    input clk,
    input rst_n,
    input [8:0] core_id,
    output reg [31:0] instruction,
    output reg [31:0] pc_out,
    output reg valid_instruction
);

    // Simple core manager for scheduling instructions
    reg [31:0] core_instructions [0:511];
    
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            instruction <= 32'h0;
            valid_instruction <= 1'b0;
        end else begin
            instruction <= core_instructions[core_id];
            valid_instruction <= 1'b1;
        end
    end

endmodule
```

**testbench/tb_evocore.v**
```verilog
module tb_evocore;

    reg clk;
    reg rst_n;
    
    // Clock generation
    initial begin
        clk = 0;
        forever #5 clk = ~clk; // 10ns period clock
    end
    
    // Test stimulus
    initial begin
        rst_n = 0;
        #10 rst_n = 1;
        
        // Add more test cases here
        
        #1000 $finish;
    end
    
    // Instantiate top module
    evocore_top uut (
        .clk(clk),
        .rst_n(rst_n)
    );

endmodule
```