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#!/usr/bin/env python

"""Generate Verilog Implementation of Instructions

The area optimized implementation uses a CPU like architecture.

+ Instructions are implemented in block RAM.

+ Registers are implemented in dual port RAM.

+ Only one instruction can be executed at a time.

+ The CPU uses a pipeline architecture, and will take 2 clocks to execute a taken branch.

+ A minimal instruction set is determined at compile time, and only those instructions are implemented.

"""

__author__ = "Jon Dawson"

__copyright__ = "Copyright (C) 2013, Jonathan P Dawson"

__version__ = "0.1"

import fpu

def unique(l):

    """In the absence of set in older python implementations, make list values unique"""

    return dict(zip(l, l)).keys()

def log2(instructions):

    """Integer only algorithm to calculate the number of bits needed to store a number"""

    bits = 1

    power = 2

    while power < instructions:

        bits += 1

        power *= 2

    return bits

def print_verilog_literal(size, value):

    """Print a verilog literal with expicilt size"""

    if(value >= 0):

        return "%s'd%s"%(size, value)

    else:

        return "-%s'd%s"%(size, abs(value))

def remove_register_hazards(instructions):

    """search through instructions, and remove register hazards"""

    wait_2_for = None

    wait_1_for = None

    new_instructions = []

    for instruction in instructions:

        wait = 0

        if "src" in instruction:

            if instruction["src"] == wait_1_for:

                wait = max(wait, 1)

            if instruction["src"] == wait_2_for:

                wait = max(wait, 2)

        if "srcb" in instruction:

            if instruction["srcb"] == wait_1_for:

                wait = max(wait, 1)

            if instruction["srcb"] == wait_2_for:

                wait = max(wait, 2)

        for i in range(wait):

            new_instructions.append({"op":"nop"})

        new_instructions.append(instruction)

        if instruction["op"] != "label":

            wait_1_for = wait_2_for

            if "dest" in instruction:

                wait_2_for = instruction["dest"]

            else:

                wait_2_for = None

    return new_instructions

def generate_instruction_set(instructions):

    """Calculate the required instruction set"""

    instruction_set = []

    instruction_memory = []

    for instruction in instructions:

        opcode = {}

        encoded_instruction = {}

        encoded_instruction["dest"] = 0

        encoded_instruction["src"] = 0

        encoded_instruction["srcb"] = 0

        encoded_instruction["literal"] = 0

        encoded_instruction["float"] = True

        opcode["op"] = instruction["op"]

        opcode["right"] = False

        opcode["unsigned"] = False

        opcode["literal"] = False

        opcode["float"] = False

        if "signed" in instruction:

            opcode["unsigned"] = not instruction["signed"]

        if "element_size" in instruction:

            opcode["element_size"] = instruction["element_size"]

        if "file_name" in instruction:

            opcode["file_name"] = instruction["file_name"]

        if "file" in instruction:

            opcode["file"] = instruction["file"]

        if "line" in instruction:

            opcode["line"] = instruction["line"]

        if "input" in instruction:

            opcode["input"] = instruction["input"]

        if "output" in instruction:

            opcode["output"] = instruction["output"]

        if "dest" in instruction:

            encoded_instruction["dest"] = instruction["dest"]

        if "src" in instruction:

            encoded_instruction["src"] = instruction["src"]

        if "srcb" in instruction:

            encoded_instruction["srcb"] = instruction["srcb"]

        if "left" in instruction:

            opcode["literal"] = True

            encoded_instruction["literal"] = instruction["left"]

        if "right" in instruction:

            opcode["literal"] = True

            opcode["right"] = True

            encoded_instruction["literal"] = instruction["right"]

        if "type" in instruction:

            if instruction["type"] == "float":

                opcode["float"] = True

                encoded_instruction["float"] = True

        if "literal" in instruction:

            opcode["literal"] = True

            encoded_instruction["literal"] = instruction["literal"]

        if "label" in instruction:

            opcode["literal"] = True

            encoded_instruction["literal"] = instruction["label"]

        if opcode not in instruction_set:

            instruction_set.append(opcode)

        for op, test_opcode in enumerate(instruction_set):

            if test_opcode == opcode:

                encoded_instruction["op"] = op

                encoded_instruction["comment"] = repr(instruction)

                instruction_memory.append(encoded_instruction)

                break

    return instruction_set, instruction_memory

def calculate_jumps(instructions):

    """change symbolic labels into numeric addresses"""

    #calculate the values of jump locations

    location = 0

    labels = {}

    new_instructions = []

    for instruction in instructions:

        if instruction["op"] == "label":

            labels[instruction["label"]] = location

        else:

            new_instructions.append(instruction)

            location += 1

    instructions = new_instructions

    #substitue real values for labeled jump locations

    for instruction in instructions:

        if "label" in instruction:

            instruction["label"]=labels[instruction["label"]]

    return instructions

def generate_declarations(instructions, no_tb_mode, register_bits, opcode_bits):

    """Generate verilog declarations"""

    #list all inputs and outputs used in the program

    inputs = unique([i["input"] for i in instructions if "input" in i])

    outputs = unique([i["output"] for i in instructions if "output" in i])

    input_files = unique([i["file_name"] for i in instructions if "file_read" == i["op"]])

    output_files = unique([i["file_name"] for i in instructions if "file_write" == i["op"]])

    testbench = not inputs and not outputs and not no_tb_mode

    #Do not generate a port in testbench mode

    inports = [

      ("input_" + i, 16) for i in inputs

    ] + [

      ("input_" + i + "_stb", 1) for i in inputs

    ] + [

      ("output_" + i + "_ack", 1) for i in outputs

    ]

    outports = [

      ("output_" + i, 16) for i in outputs

    ] + [

      ("output_" + i + "_stb", 1) for i in outputs

    ] + [

      ("input_" + i + "_ack", 1) for i in inputs

    ]

    #create list of signals

    signals = [

      ("timer", 16),

      ("timer_enable", 1),

      ("stage_0_enable", 1),

      ("stage_1_enable", 1),

      ("stage_2_enable", 1),

      ("program_counter", log2(len(instructions))),

      ("program_counter_0", log2(len(instructions))),

      ("instruction_0", 32 + register_bits*2 + opcode_bits),

      ("opcode_0", opcode_bits),

      ("dest_0", register_bits),

      ("src_0", register_bits),

      ("srcb_0", register_bits),

      ("literal_0", 32),

      ("program_counter_1", log2(len(instructions))),

      ("opcode_1", opcode_bits),

      ("dest_1", register_bits),

      ("register_1", 32),

      ("registerb_1", 32),

      ("literal_1", 32),

      ("dest_2", register_bits),

      ("result_2", 32),

      ("write_enable_2", 1),

      ("address_2", 16),

      ("data_out_2", 16),

      ("data_in_2", 16),

      ("memory_enable_2", 1),

      ("address_4", 16),

      ("data_out_4", 32),

      ("data_in_4", 32),

      ("memory_enable_4", 1),

    ] + [

      ("s_output_" + i + "_stb", 16) for i in outputs

    ] + [

      ("s_output_" + i, 16) for i in outputs

    ] + [

      ("s_input_" + i + "_ack", 16) for i in inputs

    ]

    if testbench:

        signals.append(("clk", 1))

        signals.append(("rst", 1))

    else:

        inports.append(("clk", 1))

        inports.append(("rst", 1))

    return inputs, outputs, input_files, output_files, testbench, inports, outports, signals

def floating_point_enables(instruction_set):

    enable_adder = False

    enable_multiplier = False

    enable_divider = False

    enable_int_to_float = False

    enable_float_to_int = False

    for i in instruction_set:

        if i["op"] == "+" and i["float"]:

            enable_adder = True

        if i["op"] == "-" and i["float"]:

            enable_adder = True

        if i["op"] == "*" and i["float"]:

            enable_multiplier = True

        if i["op"] == "/" and i["float"]:

            enable_divider = True

        if i["op"] == "int_to_float":

            enable_int_to_float = True

        if i["op"] == "float_to_int":

            enable_float_to_int = True

    return (

        enable_adder,

        enable_multiplier,

        enable_divider,

        enable_int_to_float,

        enable_float_to_int)

def generate_CHIP(input_file,

                  name,

                  instructions,

                  output_file,

                  registers,

                  memory_size_2,

                  memory_size_4,

                  initialize_memory,

                  memory_content_2,

                  memory_content_4,

                  no_tb_mode=False):

    """A big ugly function to crunch through all the instructions and generate the CHIP equivilent"""

    instructions = remove_register_hazards(instructions)

    instructions = calculate_jumps(instructions)

    instruction_set, instruction_memory = generate_instruction_set(instructions)

    register_bits = log2(len(registers));

    opcode_bits = log2(len(instruction_set));

    instruction_bits = 32 + register_bits*2 + opcode_bits

    declarations = generate_declarations(instructions, no_tb_mode, register_bits, opcode_bits)

    inputs, outputs, input_files, output_files, testbench, inports, outports, signals = declarations

    enable_adder, enable_multiplier, enable_divider, enable_int_to_float, enable_float_to_int = floating_point_enables(instruction_set)

    #output the code in verilog

    output_file.write("//////////////////////////////////////////////////////////////////////////////\n")

    output_file.write("//name : %s\n"%name)

    for i in inputs:

        output_file.write("//input : input_%s:16\n"%i)

    for i in outputs:

        output_file.write("//output : output_%s:16\n"%i)

    output_file.write("//source_file : %s\n"%input_file)

    output_file.write("///%s\n"%"".join(["=" for i in name]))

    output_file.write("///\n")

    output_file.write("///Created by C2CHIP\n\n")

    if enable_adder:

        output_file.write(fpu.adder)

    if enable_divider:

        output_file.write(fpu.divider)

    if enable_multiplier:

        output_file.write(fpu.multiplier)

    if enable_int_to_float:

        output_file.write(fpu.int_to_float)

    if enable_float_to_int:

        output_file.write(fpu.float_to_int)

    output_file.write("//////////////////////////////////////////////////////////////////////////////\n")

    output_file.write("// Register Allocation\n")

    output_file.write("// ===================\n")

    output_file.write("//   %s   %s   %s  \n"%("Register".center(20), "Name".center(20), "Size".center(20)))

    for register, definition in registers.iteritems():

        register_name, size = definition

        output_file.write("//   %s   %s   %s  \n"%(str(register).center(20), register_name.center(20), str(size).center(20)))

    output_file.write("module %s"%name)

    all_ports = [name for name, size in inports + outports]

    if all_ports:

        output_file.write("(")

        output_file.write(",".join(all_ports))

        output_file.write(");\n")

    else:

        output_file.write(";\n")

    output_file.write("  integer file_count;\n")

    if enable_adder:

        generate_adder_signals(output_file)

    if enable_multiplier:

        generate_multiplier_signals(output_file)

    if enable_divider:

        generate_divider_signals(output_file)

    if enable_int_to_float:

        generate_int_to_float_signals(output_file)

    if enable_float_to_int:

        generate_float_to_int_signals(output_file)

    output_file.write("  real fp_value;\n")

    if enable_adder or enable_multiplier or enable_divider or enable_int_to_float or enable_float_to_int:

        output_file.write("  parameter wait_go = 2'd0,\n")

        output_file.write("            write_a = 2'd1,\n")

        output_file.write("            write_b = 2'd2,\n")

        output_file.write("            read_z  = 2'd3;\n")

    input_files = dict(zip(input_files, ["input_file_%s"%i for i, j in enumerate(input_files)]))

    for i in input_files.values():

        output_file.write("  integer %s;\n"%i)

    output_files = dict(zip(output_files, ["output_file_%s"%i for i, j in enumerate(output_files)]))

    for i in output_files.values():

        output_file.write("  integer %s;\n"%i)

    def write_declaration(object_type, name, size, value=None):

        if size == 1:

            output_file.write(object_type)

            output_file.write(name)

            if value is not None:

                output_file.write("= %s'd%s"%(size,value))

            output_file.write(";\n")

        else:

            output_file.write(object_type)

            output_file.write("[%i:0]"%(size-1))

            output_file.write(" ")

            output_file.write(name)

            if value is not None:

                output_file.write("= %s'd%s"%(size,value))

            output_file.write(";\n")

    for name, size in inports:

        write_declaration("  input ", name, size)

    for name, size in outports:

        write_declaration("  output ", name, size)

    for name, size in signals:

        write_declaration("  reg ", name, size)

    memory_size_2 = int(memory_size_2)

    memory_size_4 = int(memory_size_4)

    if memory_size_2:

        output_file.write("  reg [15:0] memory_2 [%i:0];\n"%(memory_size_2-1))

    if memory_size_4:

        output_file.write("  reg [31:0] memory_4 [%i:0];\n"%(memory_size_4-1))

    output_file.write("  reg [%s:0] instructions [%i:0];\n"%(instruction_bits-1, len(instructions)-1))

    output_file.write("  reg [31:0] registers [%i:0];\n"%(len(registers)-1))

    #generate clock and reset in testbench mode

    if testbench:

        output_file.write("\n  //////////////////////////////////////////////////////////////////////////////\n")

        output_file.write("  // CLOCK AND RESET GENERATION                                                 \n")

        output_file.write("  //                                                                            \n")

        output_file.write("  // This file was generated in test bench mode. In this mode, the verilog      \n")

        output_file.write("  // output file can be executed directly within a verilog simulator.           \n")

        output_file.write("  // In test bench mode, a simulated clock and reset signal are generated within\n")

        output_file.write("  // the output file.                                                           \n")

        output_file.write("  // Verilog files generated in testbecnch mode are not suitable for synthesis, \n")

        output_file.write("  // or for instantiation within a larger design.\n")

        output_file.write("  \n  initial\n")

        output_file.write("  begin\n")

        output_file.write("    rst <= 1'b1;\n")

        output_file.write("    #50 rst <= 1'b0;\n")

        output_file.write("  end\n\n")

        output_file.write("  \n  initial\n")

        output_file.write("  begin\n")

        output_file.write("    clk <= 1'b0;\n")

        output_file.write("    while (1) begin\n")

        output_file.write("      #5 clk <= ~clk;\n")

        output_file.write("    end\n")

        output_file.write("  end\n\n")

    #Instance Floating Point Arithmetic

    if enable_adder or enable_multiplier or enable_divider or enable_int_to_float or enable_float_to_int:

        output_file.write("\n  //////////////////////////////////////////////////////////////////////////////\n")

        output_file.write("  // Floating Point Arithmetic                                                  \n")

        output_file.write("  //                                                                            \n")

        output_file.write("  // Generate IEEE 754 single precision divider, adder and multiplier           \n")

        output_file.write("  //                                                                            \n")

        if enable_divider:

            connect_divider(output_file)

        if enable_multiplier:

            connect_multiplier(output_file)

        if enable_adder:

            connect_adder(output_file)

        if enable_int_to_float:

            connect_int_to_float(output_file)

        if enable_float_to_int:

            connect_float_to_int(output_file)

    #Generate a state machine to execute the instructions

    binary_operators = ["+", "-", "*", "/", "|", "&", "^", "<<", ">>", "<",">", ">=",

      "<=", "==", "!="]

    if initialize_memory and (memory_content_2 or memory_content_4):

        output_file.write("\n  //////////////////////////////////////////////////////////////////////////////\n")

        output_file.write("  // MEMORY INITIALIZATION                                                      \n")

        output_file.write("  //                                                                            \n")

        output_file.write("  // In order to reduce program size, array contents have been stored into      \n")

        output_file.write("  // memory at initialization. In an FPGA, this will result in the memory being \n")

        output_file.write("  // initialized when the FPGA configures.                                      \n")

        output_file.write("  // Memory will not be re-initialized at reset.                                \n")

        output_file.write("  // Dissable this behaviour using the no_initialize_memory switch              \n")

        output_file.write("  \n  initial\n")

        output_file.write("  begin\n")

        for location, content in memory_content_2.iteritems():

            output_file.write("    memory_2[%s] = %s;\n"%(location, content))

        for location, content in memory_content_4.iteritems():

            output_file.write("    memory_4[%s] = %s;\n"%(location, content))

        output_file.write("  end\n\n")

    output_file.write("\n  //////////////////////////////////////////////////////////////////////////////\n")

    output_file.write("  // INSTRUCTION INITIALIZATION                                                 \n")

    output_file.write("  //                                                                            \n")

    output_file.write("  // Initialise the contents of the instruction memory                          \n")

    output_file.write("  //\n")

    output_file.write("  // Intruction Set\n")

    output_file.write("  // ==============\n")

    for num, opcode in enumerate(instruction_set):

        output_file.write("  // %s %s\n"%(num, opcode))

    output_file.write("  // Intructions\n")

    output_file.write("  // ===========\n")

    output_file.write("  \n  initial\n")

    output_file.write("  begin\n")

    for location, instruction in enumerate(instruction_memory):

        output_file.write("    instructions[%s] = {%s, %s, %s, %s};//%s\n"%(

            location,

            print_verilog_literal(opcode_bits, instruction["op"]),

            print_verilog_literal(register_bits, instruction["dest"]),

            print_verilog_literal(register_bits, instruction["src"]),

            print_verilog_literal(32, instruction["srcb"] | instruction["literal"]),

            instruction["comment"]))

    output_file.write("  end\n\n")

    if input_files or output_files:

        output_file.write("\n  //////////////////////////////////////////////////////////////////////////////\n")

        output_file.write("  // OPEN FILES                                                                 \n")

        output_file.write("  //                                                                            \n")

        output_file.write("  // Open all files used at the start of the process                            \n")

        output_file.write("  \n  initial\n")

        output_file.write("  begin\n")

        for file_name, file_ in input_files.iteritems():

            output_file.write("    %s = $fopenr(\"%s\");\n"%(file_, file_name))

        for file_name, file_ in output_files.iteritems():

            output_file.write("    %s = $fopen(\"%s\");\n"%(file_, file_name))

        output_file.write("  end\n\n")

    output_file.write("\n  //////////////////////////////////////////////////////////////////////////////\n")

    output_file.write("  // CPU IMPLEMENTAION OF C PROCESS                                             \n")

    output_file.write("  //                                                                            \n")

    output_file.write("  // This section of the file contains a CPU implementing the C process.        \n")

    output_file.write("  \n  always @(posedge clk)\n")

    output_file.write("  begin\n\n")

    if memory_size_2:

        output_file.write("    //implement memory for 2 byte x n arrays\n")

        output_file.write("    if (memory_enable_2 == 1'b1) begin\n")

        output_file.write("      memory_2[address_2] <= data_in_2;\n")

        output_file.write("    end\n")

        output_file.write("    data_out_2 <= memory_2[address_2];\n")

        output_file.write("    memory_enable_2 <= 1'b0;\n\n")

    if memory_size_4:

        output_file.write("    //implement memory for 4 byte x n arrays\n")

        output_file.write("    if (memory_enable_4 == 1'b1) begin\n")

        output_file.write("      memory_4[address_4] <= data_in_4;\n")

        output_file.write("    end\n")

        output_file.write("    data_out_4 <= memory_4[address_4];\n")

        output_file.write("    memory_enable_4 <= 1'b0;\n\n")

    output_file.write("    write_enable_2 <= 0;\n")

    if enable_divider:

        output_file.write("    divider_go <= 0;\n")

    if enable_multiplier:

        output_file.write("    multiplier_go <= 0;\n")

    if enable_adder:

        output_file.write("    adder_go <= 0;\n")

    if enable_int_to_float:

        output_file.write("    int_to_float_go <= 0;\n")

    if enable_float_to_int:

        output_file.write("    float_to_int_go <= 0;\n")

    output_file.write("    //stage 0 instruction fetch\n")

    output_file.write("    if (stage_0_enable) begin\n")

    output_file.write("      stage_1_enable <= 1;\n")

    output_file.write("      instruction_0 <= instructions[program_counter];\n")

    output_file.write("      opcode_0 = instruction_0[%s:%s];\n"%(

        register_bits * 2 + opcode_bits + 31,

        register_bits * 2 + 32))

    output_file.write("      dest_0 = instruction_0[%s:%s];\n"%(

        register_bits * 2 + 31,

        register_bits + 32))

    output_file.write("      src_0 = instruction_0[%s:32];\n"%(

        register_bits + 31))

    output_file.write("      srcb_0 = instruction_0[%s:0];\n"%(register_bits-1))

    output_file.write("      literal_0 = instruction_0[31:0];\n")

    output_file.write("      if(write_enable_2) begin\n")

    output_file.write("        registers[dest_2] <= result_2;\n")

    output_file.write("      end\n")

    output_file.write("      program_counter_0 <= program_counter;\n")

    output_file.write("      program_counter <= program_counter + 1;\n")

    output_file.write("    end\n\n")

    output_file.write("    //stage 1 opcode fetch\n")

    output_file.write("    if (stage_1_enable) begin\n")

    output_file.write("      stage_2_enable <= 1;\n")

    output_file.write("      register_1 <= registers[src_0];\n")

    output_file.write("      registerb_1 <= registers[srcb_0];\n")

    output_file.write("      dest_1 <= dest_0;\n")

    output_file.write("      literal_1 <= literal_0;\n")

    output_file.write("      opcode_1 <= opcode_0;\n")

    output_file.write("      program_counter_1 <= program_counter_0;\n")

    output_file.write("    end\n\n")

    output_file.write("    //stage 2 opcode fetch\n")

    output_file.write("    if (stage_2_enable) begin\n")

    output_file.write("      dest_2 <= dest_1;\n")

    output_file.write("      case(opcode_1)\n\n")

    #A frame is executed in each state

    for opcode, instruction in enumerate(instruction_set):

        if instruction["op"] == "literal":

            output_file.write("        16'd%s:\n"%(opcode))

            output_file.write("        begin\n")

            output_file.write("          result_2 <= literal_1;\n")

            output_file.write("          write_enable_2 <= 1;\n")

            output_file.write("        end\n\n")

        elif instruction["op"] == "move":

            output_file.write("        16'd%s:\n"%(opcode))

            output_file.write("        begin\n")

            output_file.write("          result_2 <= register_1;\n")

            output_file.write("          write_enable_2 <= 1;\n")

            output_file.write("        end\n\n")

        elif instruction["op"] == "~":