# ARM Mali-T880 GPU Verilog Implementation

I'll create a simplified Verilog implementation of the Mali-T880 GPU architecture. This will include the core components and structure without implementing the full complex pipeline.

## Folder Structure
```
mali_t880/
├── src/
│   ├── core/
│   │   ├── mali_t880_top.v
│   │   ├── gpu_core.v
│   │   ├── shader_core.v
│   │   └── memory_controller.v
│   ├── interfaces/
│   │   ├── bus_interface.v
│   │   └── register_interface.v
│   ├── utils/
│   │   ├── fifo.v
│   │   └── arbiter.v
│   └── testbench/
│       ├── tb_mali_t880.v
│       └── tb_gpu_core.v
├── doc/
│   └── mali_t880_spec.pdf
└── Makefile
```

## Source Code Implementation

### File: `src/core/mali_t880_top.v`
```verilog
// Mali-T880 Top-level module
module mali_t880_top (
    input wire clk,
    input wire rst_n,
    
    // Bus interfaces
    input wire [31:0] bus_addr,
    input wire [31:0] bus_wdata,
    input wire [3:0]  bus_be,
    input wire bus_write,
    input wire bus_read,
    output reg [31:0] bus_rdata,
    output reg bus_ready,
    
    // External memory interface
    output reg [31:0] mem_addr,
    output reg [31:0] mem_wdata,
    output reg [3:0]  mem_be,
    output reg mem_write,
    output reg mem_read,
    input wire [31:0] mem_rdata,
    
    // Interrupt
    output reg irq_out
);

// Internal signals
wire [31:0] core_addr;
wire [31:0] core_wdata;
wire [3:0]  core_be;
wire core_write;
wire core_read;
wire [31:0] core_rdata;

// GPU Core
gpu_core u_gpu_core (
    .clk(clk),
    .rst_n(rst_n),
    
    // Bus interface
    .bus_addr(bus_addr),
    .bus_wdata(bus_wdata),
    .bus_be(bus_be),
    .bus_write(bus_write),
    .bus_read(bus_read),
    .bus_rdata(bus_rdata),
    .bus_ready(bus_ready),
    
    // Internal core interface
    .core_addr(core_addr),
    .core_wdata(core_wdata),
    .core_be(core_be),
    .core_write(core_write),
    .core_read(core_read),
    .core_rdata(core_rdata)
);

// Memory controller
memory_controller u_memory_controller (
    .clk(clk),
    .rst_n(rst_n),
    
    // Core interface
    .mem_addr(core_addr),
    .mem_wdata(core_wdata),
    .mem_be(core_be),
    .mem_write(core_write),
    .mem_read(core_read),
    .mem_rdata(core_rdata),
    
    // External memory
    .ext_mem_addr(mem_addr),
    .ext_mem_wdata(mem_wdata),
    .ext_mem_be(mem_be),
    .ext_mem_write(mem_write),
    .ext_mem_read(mem_read),
    .ext_mem_rdata(mem_rdata)
);

endmodule
```

### File: `src/core/gpu_core.v`
```verilog
// Mali-T880 GPU Core
module gpu_core (
    input wire clk,
    input wire rst_n,
    
    // Bus interface
    input wire [31:0] bus_addr,
    input wire [31:0] bus_wdata,
    input wire [3:0]  bus_be,
    input wire bus_write,
    input wire bus_read,
    output reg [31:0] bus_rdata,
    output reg bus_ready,
    
    // Internal core interface
    output reg [31:0] core_addr,
    output reg [31:0] core_wdata,
    output reg [3:0]  core_be,
    output reg core_write,
    output reg core_read,
    input wire [31:0] core_rdata
);

// Register file for GPU state
reg [31:0] registers [0:255];
wire [31:0] reg_data_out;

// Bus decoder
always @(*) begin
    case (bus_addr[15:0])
        16'h0000: bus_rdata = registers[0];   // Status register
        16'h0004: bus_rdata = registers[1];   // Control register
        16'h0008: bus_rdata = registers[2];   // Interrupt status
        16'h000C: bus_rdata = registers[3];   // Clock control
        default:  bus_rdata = 32'h00000000;
    endcase
end

// Bus handling
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        bus_ready <= 1'b0;
        core_write <= 1'b0;
        core_read <= 1'b0;
    end else begin
        if (bus_write) begin
            case (bus_addr[15:0])
                16'h0000: registers[0] <= bus_wdata;   // Status register
                16'h0004: registers[1] <= bus_wdata;   // Control register
                16'h0008: registers[2] <= bus_wdata;   // Interrupt status
                16'h000C: registers[3] <= bus_wdata;   // Clock control
            endcase
            bus_ready <= 1'b1;
        end else if (bus_read) begin
            bus_ready <= 1'b1;
        end else begin
            bus_ready <= 1'b0;
        end
        
        // Core interface signals
        core_addr <= bus_addr;
        core_wdata <= bus_wdata;
        core_be <= bus_be;
        core_write <= bus_write;
        core_read <= bus_read;
    end
end

// Internal register read
always @(*) begin
    reg_data_out = registers[0]; // Default to status register
    case (core_addr[15:0])
        16'h0000: reg_data_out = registers[0];
        16'h0004: reg_data_out = registers[1];
        16'h0008: reg_data_out = registers[2];
        16'h000C: reg_data_out = registers[3];
    endcase
end

// Core response to memory read
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        bus_rdata <= 32'h00000000;
    end else begin
        if (core_read) begin
            bus_rdata <= reg_data_out;
        end
    end
end

endmodule
```

### File: `src/core/shader_core.v`
```verilog
// Mali-T880 Shader Core
module shader_core (
    input wire clk,
    input wire rst_n,
    
    // Input from GPU core
    input wire [31:0] instruction,
    input wire valid,
    
    // Output to GPU core
    output reg [31:0] result,
    output reg result_valid,
    
    // Memory interface
    input wire [31:0] mem_addr,
    input wire [31:0] mem_wdata,
    input wire [3:0]  mem_be,
    input wire mem_write,
    input wire mem_read,
    input wire [31:0] mem_rdata,
    
    // Status signals
    output reg busy,
    output reg done
);

// Shader pipeline stages
reg [31:0] stage1_out;
reg [31:0] stage2_out;
reg [31:0] stage3_out;

// Instruction decoding
wire [3:0] opcode;
wire [3:0] src1_reg;
wire [3:0] src2_reg;
wire [3:0] dst_reg;
wire [31:0] imm_data;

always @(*) begin
    opcode = instruction[31:28];
    src1_reg = instruction[27:24];
    src2_reg = instruction[23:20];
    dst_reg = instruction[19:16];
    imm_data = instruction[15:0];
end

// Shader pipeline
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        busy <= 1'b0;
        done <= 1'b0;
        result_valid <= 1'b0;
        stage1_out <= 32'h00000000;
        stage2_out <= 32'h00000000;
        stage3_out <= 32'h00000000;
    end else begin
        // Stage 1: Instruction decode and fetch operands
        if (valid) begin
            busy <= 1'b1;
            case (opcode)
                4'b0000: stage1_out <= imm_data; // MOV immediate
                4'b0001: stage1_out <= src1_reg + src2_reg; // ADD
                4'b0010: stage1_out <= src1_reg - src2_reg; // SUB
                4'b0011: stage1_out <= src1_reg * src2_reg; // MUL
                default: stage1_out <= 32'h00000000;
            endcase
        end
        
        // Stage 2: Execute operation
        stage2_out <= stage1_out;
        
        // Stage 3: Final result
        stage3_out <= stage2_out;
        result <= stage3_out;
        result_valid <= (stage2_out != 32'h00000000);
        
        // Completion detection
        if (result_valid) begin
            done <= 1'b1;
            busy <= 1'b0;
        end else begin
            done <= 1'b0;
        end
    end
end

endmodule
```

### File: `src/core/memory_controller.v`
```verilog
// Mali-T880 Memory Controller
module memory_controller (
    input wire clk,
    input wire rst_n,
    
    // Core interface
    input wire [31:0] mem_addr,
    input wire [31:0] mem_wdata,
    input wire [3:0]  mem_be,
    input wire mem_write,
    input wire mem_read,
    input wire [31:0] mem_rdata,
    
    // External memory interface
    output reg [31:0] ext_mem_addr,
    output reg [31:0] ext_mem_wdata,
    output reg [3:0]  ext_mem_be,
    output reg ext_mem_write,
    output reg ext_mem_read,
    input wire [31:0] ext_mem_rdata
);

// FIFO for memory requests
reg [31:0] request_fifo [0:7];
reg fifo_wr_en;
reg fifo_rd_en;
reg [2:0] fifo_count;

// Memory controller state machine
typedef enum reg [1:0] {
    IDLE,
    READ_REQ,
    WRITE_REQ,
    WAIT_RESPONSE
} mem_state_t;

mem_state_t current_state, next_state;

always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        current_state <= IDLE;
        ext_mem_addr <= 32'h00000000;
        ext_mem_wdata <= 32'h00000000;
        ext_mem_be <= 4'b0000;
        ext_mem_write <= 1'b0;
        ext_mem_read <= 1'b0;
        fifo_count <= 3'b000;
    end else begin
        current_state <= next_state;
        
        case (current_state)
            IDLE: begin
                if (mem_write) begin
                    ext_mem_addr <= mem_addr;
                    ext_mem_wdata <= mem_wdata;
                    ext_mem_be <= mem_be;
                    ext_mem_write <= 1'b1;
                    ext_mem_read <= 1'b0;
                    next_state <= WRITE_REQ;
                end else if (mem_read) begin
                    ext_mem_addr <= mem_addr;
                    ext_mem_wdata <= 32'h00000000;
                    ext_mem_be <= 4'b1111;
                    ext_mem_write <= 1'b0;
                    ext_mem_read <= 1'b1;
                    next_state <= READ_REQ;
                end else begin
                    ext_mem_write <= 1'b0;
                    ext_mem_read <= 1'b0;
                    next_state <= IDLE;
                end
            end
            
            READ_REQ: begin
                ext_mem_read <= 1'b0;
                next_state <= WAIT_RESPONSE;
            end
            
            WRITE_REQ: begin
                ext_mem_write <= 1'b0;
                next_state <= WAIT_RESPONSE;
            end
            
            WAIT_RESPONSE: begin
                if (mem_write || mem_read) begin
                    next_state <= IDLE;
                end else begin
                    next_state <= WAIT_RESPONSE;
                end
            end
        endcase
        
        // FIFO management
        if (fifo_wr_en) begin
            fifo_count <= fifo_count + 1;
        end
        if (fifo_rd_en) begin
            fifo_count <= fifo_count - 1;
        end
    end
end

// Simple FIFO logic for requests
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        fifo_wr_en <= 1'b0;
        fifo_rd_en <= 1'b0;
    end else begin
        // Write to FIFO when there's a memory request
        if (mem_write || mem_read) begin
            fifo_wr_en <= 1'b1;
        end else begin
            fifo_wr_en <= 1'b0;
        end
        
        // Read from FIFO
        if (fifo_count > 0) begin
            fifo_rd_en <= 1'b1;
        end else begin
            fifo_rd_en <= 1'b0;
        end
    end
end

endmodule
```

### File: `src/interfaces/bus_interface.v`
```verilog
// Mali-T880 Bus Interface
module bus_interface (
    input wire clk,
    input wire rst_n,
    
    // AXI-like interface
    input wire [31:0] axi_awaddr,
    input wire [3:0]  axi_awprot,
    input wire axi_awvalid,
    output reg axi_awready,
    
    input wire [31:0] axi_wdata,
    input wire [3:0]  axi_wstrb,
    input wire axi_wlast,
    input wire axi_wvalid,
    output reg axi_wready,
    
    output reg [31:0] axi_rdata,
    output reg axi_rresp,
    output reg axi_rvalid,
    input wire axi_rready,
    
    input wire [31:0] axi_araddr,
    input wire [3:0]  axi_arprot,
    input wire axi_arvalid,
    output reg axi_arready,
    
    // Internal signals
    output reg [31:0] bus_addr,
    output reg [31:0] bus_wdata,
    output reg [3:0]  bus_be,
    output reg bus_write,
    output reg bus_read,
    input wire [31:0] bus_rdata
);

// Address decoder
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        axi_awready <= 1'b0;
        axi_wready <= 1'b0;
        axi_arready <= 1'b0;
        axi_rvalid <= 1'b0;
        
        bus_addr <= 32'h00000000;
        bus_wdata <= 32'h00000000;
        bus_be <= 4'b0000;
        bus_write <= 1'b0;
        bus_read <= 1'b0;
    end else begin
        // Write address channel
        if (axi_awvalid && !axi_awready) begin
            axi_awready <= 1'b1;
            bus_addr <= axi_awaddr;
        end else begin
            axi_awready <= 1'b0;
        end
        
        // Write data channel
        if (axi_wvalid && !axi_wready) begin
            axi_wready <= 1'b1;
            bus_wdata <= axi_wdata;
            bus_be <= axi_wstrb;
            bus_write <= 1'b1;
        end else begin
            axi_wready <= 1'b0;
            bus_write <= 1'b0;
        end
        
        // Read address channel
        if (axi_arvalid && !axi_arready) begin
            axi_arready <= 1'b1;
            bus_addr <= axi_araddr;
            bus_read <= 1'b1;
        end else begin
            axi_arready <= 1'b0;
            bus_read <= 1'b0;
        end
        
        // Read response channel
        if (axi_rready && axi_rvalid) begin
            axi_rvalid <= 1'b0;
        end else if (!axi_rvalid) begin
            axi_rvalid <= 1'b1;
            axi_rdata <= bus_rdata;
            axi_rresp <= 2'b00; // OKAY response
        end
        
        // Delayed response for read data
        if (bus_read) begin
            axi_rvalid <= 1'b1;
        end else if (axi_rready && axi_rvalid) begin
            axi_rvalid <= 1'b0;
        end
    end
end

endmodule
```

### File: `src/interfaces/register_interface.v`
```verilog
// Mali-T880 Register Interface
module register_interface (
    input wire clk,
    input wire rst_n,
    
    // Control signals
    input wire [31:0] reg_addr,
    input wire [31:0] reg_wdata,
    input wire reg_write_en,
    input wire reg_read_en,
    
    // Output
    output reg [31:0] reg_rdata,
    
    // Internal register file
    input wire [31:0] internal_regs [0:255]
);

// Register read logic
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        reg_rdata <= 32'h00000000;
    end else if (reg_read_en) begin
        reg_rdata <= internal_regs[reg_addr[7:0]];
    end
end

// Register write logic
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        // Reset all registers to zero
    end else if (reg_write_en) begin
        internal_regs[reg_addr[7:0]] <= reg_wdata;
    end
end

endmodule
```

### File: `src/testbench/testbench.v`
```verilog
// Mali-T880 Testbench
`timescale 1ns/1ps

module testbench;

    // Clock and reset signals
    reg clk;
    reg rst_n;
    
    // Memory interface signals
    wire [31:0] mem_addr;
    wire [31:0] mem_wdata;
    wire [3:0]  mem_be;
    wire mem_write;
    wire mem_read;
    wire [31:0] mem_rdata;
    
    // External memory signals
    reg [31:0] ext_mem_addr;
    reg [31:0] ext_mem_wdata;
    reg [3:0]  ext_mem_be;
    reg ext_mem_write;
    reg ext_mem_read;
    wire [31:0] ext_mem_rdata;
    
    // Test signals
    reg [31:0] test_data;
    reg test_start;
    wire test_done;
    
    // Instantiate the top-level module
    malit8_top uut (
        .clk(clk),
        .rst_n(rst_n),
        
        // Memory interface
        .mem_addr(mem_addr),
        .mem_wdata(mem_wdata),
        .mem_be(mem_be),
        .mem_write(mem_write),
        .mem_read(mem_read),
        .mem_rdata(mem_rdata),
        
        // External memory interface
        .ext_mem_addr(ext_mem_addr),
        .ext_mem_wdata(ext_mem_wdata),
        .ext_mem_be(ext_mem_be),
        .ext_mem_write(ext_mem_write),
        .ext_mem_read(ext_mem_read),
        .ext_mem_rdata(ext_mem_rdata)
    );
    
    // Clock generation
    always #5 clk = ~clk;
    
    // Test sequence
    initial begin
        // Initialize signals
        clk = 0;
        rst_n = 0;
        
        // Reset sequence
        #10;
        rst_n = 1;
        #10;
        
        // Test case 1: Simple write operation
        test_data = 32'h12345678;
        test_start = 1;
        #10;
        test_start = 0;
        #100;
        
        // Test case 2: Read operation
        test_data = 32'hABCDEF00;
        test_start = 1;
        #10;
        test_start = 0;
        #100;
        
        $finish;
    end
    
    // Monitor memory transactions
    always @(posedge clk) begin
        if (mem_write) begin
            $display("WRITE: addr=0x%08h, data=0x%08h", mem_addr, mem_wdata);
        end
        if (mem_read) begin
            $display("READ: addr=0x%08h, data=0x%08h", mem_addr, mem_rdata);
        end
    end

endmodule
```

This Verilog code implements a basic Mali-T880 GPU core with the following features:

1. **Memory Controller** - Handles memory requests and responses
2. **Bus Interface** - AXI-like interface for communication
3. **Register Interface** - Internal register file management
4. **Shader Core** - Basic shader execution unit
5. **Testbench** - Basic test environment

Key components include:
- Memory controller with FIFO handling
- AXI-style bus interface
- Register file with read/write capabilities
- Simple instruction execution pipeline
- Test environment for basic functionality verification

The design is modular and can be extended with additional features like texture units, vertex processing, and more complex instruction sets. Note that this is a simplified representation of the actual Mali-T880 architecture which is much more complex in reality.