#!/usr/bin/env python

"""
Generate core_selector.v and core_vfiles.mk for a set of cores.
"""

# History of Cryptech bus addressing scheme, as best I understand it.
#
# The old old addressing scheme that Joachim and Paul came up with
# was:
#
#  3 bits of segment  selector [16:14]
#  6 bits of core     selector [13:8]
#  8 bits of register selector [7:0]
#
# modexp6s needed more register bits than that, so Pavel changed
# addressing within the math segment to:
#
#  3 bits of segment  selector [16:14]
#  4 bits of core     selector [13:10]
# 10 bits of register selector [9:0]
#
# Meanwhile, Paul eliminated segments entirely when writing the
# ancestor of this script, resulting in:
#
#  9 bits of core     selector [16:8]
#  8 bits of register selector [7:0]
#
# Taking Pavel's and Paul's changes together, we'd get:
#
#  7 bits of core     selector [16:10]
# 10 bits of register selector [9:0]
#
# Except that this would waste space for most cores, and make things
# very confusing for the TRNG cores.  So, instead, we keep Paul's
# two-level (no segment) scheme and handle modexps6 as a set of four
# contiguous "cores" with a 10-bit composite register selector.

# The modexps6 core drags in a one clock cycle delay to other cores,
# to compensate for the extra clock cycle consumed by the block
# memories used in the modexps6 core.  We probably want a general
# solution for this, because we're going to run into this problem for
# any core that handles arguments big enough to require block memory.

# To Do:
#
# - Consider automating the one-clock-cycle delay stuff by adding
#   another boolean flag to the config file.  Default would be no
#   delay, if any included core sets the "I use block memories" flag,
#   all other cores would get the delay.  Slightly tedious but
#   something we can calculate easily enough, and probably an
#   improvement over wiring in the delay when nothing needs it.
#
# - Rename script and its config file to something more meaningful.
#
# - Figure out whether this really belongs in the novena repository at
#   all, seems more generic than that.


def main():
    """
    Parse arguments and config file, generate core list, generate output.
    """

    from argparse import ArgumentParser, FileType, ArgumentDefaultsHelpFormatter
    from sys      import exit

    parser = ArgumentParser(description = __doc__, formatter_class = ArgumentDefaultsHelpFormatter)
    parser.add_argument("-d", "--debug",   help = "enable debugging",   action = "store_true")
    parser.add_argument("-s", "--section", help = "config file section")
    parser.add_argument("-c", "--config",  help = "configuration file",   default = "config.cfg",       type = FileType("r"))
    parser.add_argument("--verilog",       help = "verilog output file",  default = "core_selector.v",  type = FileType("w"))
    parser.add_argument("--makefile",      help = "output makefile",      default = "core_vfiles.mk",   type = FileType("w"))
    parser.add_argument("core",            help = "name(s) of core(s)", nargs = "*")
    args = parser.parse_args()

    try:
        cfg = RawConfigParser()
        cfg.readfp(args.config)

        if args.core:
            cores = args.core
        else:
            section = args.section or cfg.get("default", "default-section")
            cores = cfg.get(section, "cores").split()

        cores.insert(0, "board_regs")
        cores.insert(1, "comm_regs")

        cores = tuple(Core.new(core) for core in cores)

        core_number = 0
        for core in cores:
            core_number = core.assign_core_number(core_number)

        for core in cores:
            core.configure(cfg)

        if False:

            # For some reason, attempting to optimize out the delay
            # code entirely results in a non-working bitstream.  Don't
            # know why, disabling the optimization works, so just do
            # that for now.

            Core.need_one_cycle_delay = any(core.block_memory for core in cores)

        args.verilog.write(createModule_template.format(
            addrs = "".join(core.createAddr()     for core in cores),
            insts = "".join(core.createInstance() for core in cores),
            muxes = "".join(core.createMux()      for core in cores)))

        args.makefile.write(listVfiles_template.format(
            vfiles = "".join(core.listVfiles()    for core in cores)))

    except Exception, e:
        if args.debug:
            raise
        exit(str(e))


try:
    import ConfigParser as configparser
except ImportError:
    import configparser   

class RawConfigParser(configparser.RawConfigParser):
    """
    RawConfigParser with a few extensions.
    """

    def getboolean(self, section, option, default = False):
        if self.has_option(section, option):
            # RawConfigParser is an old-stle class, super() doesn't work, feh.
            return configparser.RawConfigParser.getboolean(self, section, option)
        else:
            return default

    def getvalues(self, section, option):
        if self.has_option(section, option):
            for value in self.get(section, option).split():
                yield value


class Core(object):
    """
    Data and methods for a generic core.  We can use this directly for
    most cores, a few are weird and require subclassing to override
    particular methods.
    """

    # Class variable tracking how many times a particular core has
    # been instantiated.  This controls instance numbering.

    _instance_count = {}

    # Class variable mapping core name to subclass for special cases.

    special_class = {}

    # Class variable recording whether we need a one-cycle delay to
    # compensate for block memories.

    need_one_cycle_delay = True

    def __init__(self, name):
        self.name = name
        self.core_number = None
        self.vfiles = []
        self.error_wire = True
        self.block_memory = False
        self.instance_number = self._instance_count.get(name, 0)
        self._instance_count[name] = self.instance_number + 1

    @classmethod
    def new(cls, name):
        return cls.special_class.get(name, cls)(name)

    def assign_core_number(self, n):
        self.core_number = n
        return n + 1

    def configure(self, cfg):
        if self.instance_number == 0:
            self.vfiles.extend(cfg.getvalues(self.name, "vfiles"))
            for required in cfg.getvalues(self.name, "requires"):
                if required not in self._instance_count:
                    self.vfiles.extend(cfg.getvalues(required, "vfiles"))
        self.error_wire = cfg.getboolean(self.name, "error_wire", self.error_wire)
        self.block_memory = cfg.getboolean(self.name, "block_memory", self.block_memory)

    @property
    def instance_name(self):
        if self._instance_count[self.name] > 1:
            return "{}_{}".format(self.name, self.instance_number)
        else:
            return self.name

    @property
    def upper_instance_name(self):
        return self.instance_name.upper()

    @property
    def reset_pin(self):
        return ".reset_n(sys_rst_n)"

    @property
    def error_port(self):
        return ",\n      .error(error_{core.instance_name})".format(core = self) if self.error_wire else ""

    @property
    def one_cycle_delay(self):
        return one_cycle_delay_template.format(core = self) if self.need_one_cycle_delay and not self.block_memory else ""

    @property
    def mux_data_reg(self):
        return "read_data_" + self.instance_name + ("_reg" if self.need_one_cycle_delay and not self.block_memory else "")

    @property
    def mux_error_reg(self):
        return "error_" + self.instance_name if self.error_wire else "0"

    def createInstance(self):
        return createInstance_template_generic.format(core = self)

    def createAddr(self):
        return createAddr_template.format(core = self)

    def createMux(self):
        return createMux_template.format(core = self, core0 = self)

    def listVfiles(self):
        return "".join(" \\\n\t$(CORE_TREE)/" + vfile for vfile in self.vfiles)


class SubCore(Core):
    """"
    Override mux handling for TRNG's sub-cores.
    """

    def __init__(self, name, parent):
        super(SubCore, self).__init__(name)
        self.parent = parent

    def createMux(self):
        return createMux_template.format(core = self, core0 = self.parent)


class TRNGCore(Core):
    """
    The TRNG core has an internal mux with slots for 15 sub-cores,
    most of which are empty.  This is a bit of a mess.

    Mostly this means that our method calls have to iterate over all
    of the subcores after handling the base TRNG core, but we also use
    different templates, and fiddle with addresses a bit.

    Mux numbers have to be dug out of the TRNG Verilog source.
    """

    # TRNG subcore name -> internal mux number.
    subcore_parameters = dict(avalanche_entropy = 0x1,
                              rosc_entropy      = 0x2,
                              trng_mixer        = 0x3,
                              trng_csprng       = 0x4)

    def __init__(self, name):
        super(TRNGCore, self).__init__(name)
        self.subcores = tuple(SubCore(name, self)
                              for name in sorted(self.subcore_parameters,
                                                 key = lambda x: self.subcore_parameters[x]))

    def assign_core_number(self, n):
        n = super(TRNGCore, self).assign_core_number(n)
        for subcore in self.subcores:
            subcore.assign_core_number(self.core_number + self.subcore_parameters[subcore.name])
        return n + 15

    @property
    def last_subcore_upper_instance_name(self):
        return self.subcores[-1].upper_instance_name

    def createInstance(self):
        return createInstance_template_TRNG.format(core = self)

    def createAddr(self):
        return super(TRNGCore, self).createAddr() + "".join(subcore.createAddr() for subcore in self.subcores)

    def createMux(self):
        return super(TRNGCore, self).createMux() + "".join(subcore.createMux() for subcore in self.subcores)


class ModExpS6Core(Core):
    """
    ModExpS6 core consumes as much space as four ordinary cores, and
    uses different templates to handle the differences in timing and
    addressing.
    """

    def assign_core_number(self, n):
        n = super(ModExpS6Core, self).assign_core_number(n)
        return n + 3

    def createInstance(self):
        return createInstance_template_ModExpS6.format(core = self)

    def createMux(self):
        return createMux_modexps6_template.format(core = self, core0 = self)


# Hook special classes in as handlers for the cores that require them.

Core.special_class.update(
    trng        = TRNGCore,
    modexps6    = ModExpS6Core)


# Templates (format strings), here instead of inline in the functions
# that use them, both because some of these are shared between
# multiple functions and because it's easier to read these (and get
# the indentation right) when the're separate.

# Template used by .createAddr() methods.

createAddr_template = """\
   localparam   CORE_ADDR_{core.upper_instance_name:21s} = 9'h{core.core_number:02x};
"""

# Template used by Core.createInstance().

createInstance_template_generic = """\
   //----------------------------------------------------------------
   // {core.upper_instance_name}
   //----------------------------------------------------------------
   wire                 enable_{core.instance_name} = (addr_core_num == CORE_ADDR_{core.upper_instance_name});
   wire [31: 0]         read_data_{core.instance_name};
   wire                 error_{core.instance_name};

   {core.name} {core.instance_name}_inst
     (
      .clk(sys_clk),
      {core.reset_pin},

      .cs(enable_{core.instance_name} & (sys_eim_rd | sys_eim_wr)),
      .we(sys_eim_wr),

      .address(addr_core_reg),
      .write_data(sys_write_data),
      .read_data(read_data_{core.instance_name}){core.error_port}
      );

{core.one_cycle_delay}

"""

# Template used by ModExpS6Core.createInstance().  This is different
# enough from the base template that it's easier to make this separate.

createInstance_template_ModExpS6 = """\
   //----------------------------------------------------------------
   // {core.upper_instance_name}
   //----------------------------------------------------------------
   wire                 enable_{core.instance_name} = (addr_core_num >= CORE_ADDR_{core.upper_instance_name}) && (addr_core_num <= CORE_ADDR_{core.upper_instance_name} + 9'h03);
   wire [31: 0]         read_data_{core.instance_name};
   wire [1:0]           {core.instance_name}_prefix = addr_core_num[1:0] - CORE_ADDR_{core.upper_instance_name};

   {core.name}_wrapper {core.instance_name}_inst
     (
      .clk(sys_clk),
      {core.reset_pin},

      .cs(enable_{core.instance_name} & (sys_eim_rd | sys_eim_wr)),
      .we(sys_eim_wr),

      .address({{{core.instance_name}_prefix, addr_core_reg}}),
      .write_data(sys_write_data),
      .read_data(read_data_{core.instance_name})
      );


"""

# Template used by TRNGCore.createInstance(); this is different enough
# from the generic template that it's (probably) clearer to have this
# separate.

createInstance_template_TRNG = """\
   //----------------------------------------------------------------
   // {core.upper_instance_name}
   //----------------------------------------------------------------
   wire                 enable_{core.instance_name} = (addr_core_num >= CORE_ADDR_{core.upper_instance_name}) && (addr_core_num <= CORE_ADDR_{core.upper_instance_name} + 9'h0f);
   wire [31: 0]         read_data_{core.instance_name};
   wire                 error_{core.instance_name};
   wire [3:0]           {core.instance_name}_prefix = addr_core_num[3:0] - CORE_ADDR_{core.upper_instance_name};

   {core.name} {core.instance_name}_inst
     (
      .clk(sys_clk),
      {core.reset_pin},

      .cs(enable_{core.instance_name} & (sys_eim_rd | sys_eim_wr)),
      .we(sys_eim_wr),

      .address({{{core.instance_name}_prefix, addr_core_reg}}),
      .write_data(sys_write_data),
      .read_data(read_data_{core.instance_name}),
      .error(error_{core.instance_name}),

      .avalanche_noise(noise),
      .debug(debug)
      );

{core.one_cycle_delay}

"""

# Template for one-cycle delay code.

one_cycle_delay_template = """\
   reg  [31: 0] read_data_{core.instance_name}_reg;
   always @(posedge sys_clk)
     read_data_{core.instance_name}_reg <= read_data_{core.instance_name};
"""

# Template for .createMux() methods.

createMux_template = """\
       CORE_ADDR_{core.upper_instance_name}:
         begin
            sys_read_data_mux = {core0.mux_data_reg};
            sys_error_mux = {core0.mux_error_reg};
         end
"""

# Template for ModExpS6.createMux() method.

createMux_modexps6_template = """\
       CORE_ADDR_{core.upper_instance_name} + 0,
       CORE_ADDR_{core.upper_instance_name} + 1,
       CORE_ADDR_{core.upper_instance_name} + 2,
       CORE_ADDR_{core.upper_instance_name} + 3:
         begin
            sys_read_data_mux = {core0.mux_data_reg};
            sys_error_mux = {core0.mux_error_reg};
         end
"""


# Top-level (createModule) template.

createModule_template = """\
// NOTE: This file is generated; do not edit by hand.

module core_selector
  (
   input wire          sys_clk,
   input wire          sys_rst_n,

   input wire [16: 0]  sys_eim_addr,
   input wire          sys_eim_wr,
   input wire          sys_eim_rd,
   output wire [31: 0] sys_read_data,
   input wire [31: 0]  sys_write_data,
   output wire         sys_error,

   input wire          noise,
   output wire [7 : 0] debug
   );


   //----------------------------------------------------------------
   // Address Decoder
   //----------------------------------------------------------------
   // upper 9 bits specify core being addressed
   wire [ 8: 0]         addr_core_num   = sys_eim_addr[16: 8];
   // lower 8 bits specify register offset in core
   wire [ 7: 0]         addr_core_reg   = sys_eim_addr[ 7: 0];


   //----------------------------------------------------------------
   // Core Address Table
   //----------------------------------------------------------------
{addrs}

{insts}
   //----------------------------------------------------------------
   // Output (Read Data) Multiplexer
   //----------------------------------------------------------------
   reg [31: 0]          sys_read_data_mux;
   assign               sys_read_data = sys_read_data_mux;
   reg                  sys_error_mux;
   assign               sys_error = sys_error_mux;

   always @*

     case (addr_core_num)
{muxes}
       default:
         begin
            sys_read_data_mux = {{32{{1'b0}}}};
            sys_error_mux = 1;
         end
     endcase


endmodule


//======================================================================
// EOF core_selector.v
//======================================================================
"""

# Template for makefile snippet listing Verilog source files.

listVfiles_template = """\
# NOTE: This file is generated; do not edit by hand.

vfiles +={vfiles}
"""

# Run main program.

if __name__ == "__main__":
    main()