from nmigen import *
from nmigen.back import rtlil

from heavycomps import uart, wishbone
from minerva.core import Minerva


class SimpleWishboneSerial(Elaboratable):
    def __init__(self, tx, sys_clk_freq, baudrate=115200):
        self.tx = tx
        self.bus = wishbone.Interface()
        self.ftw = round(2**32*baudrate/sys_clk_freq)

    def elaborate(self, platform):
        m = Module()
        m.submodules.tx = tx = uart.RS232TX(self.ftw)
        m.d.comb += [
            tx.stb.eq(self.bus.cyc & self.bus.stb & self.bus.we),
            tx.data.eq(self.bus.dat_w),
            self.bus.ack.eq(tx.ack),
            self.tx.eq(tx.tx)
        ]
        return m
        

class Top(Elaboratable):
    def __init__(self):
        self.clk100 = Signal()
        self.serial_tx = Signal()

    def elaborate(self, platform):
        m = Module()

        cd_sync = ClockDomain(reset_less=True)
        m.domains += cd_sync
        m.d.comb += cd_sync.clk.eq(self.clk100)

        m.submodules.cpu = cpu = Minerva(with_icache=False, with_dcache=False)
        m.submodules.ram = ram = wishbone.SRAM(Memory(32, 1024))
        m.submodules.uart = uart = SimpleWishboneSerial(self.serial_tx, 100e6)
        m.submodules.con = con = wishbone.InterconnectShared(
            [cpu.ibus, cpu.dbus],
            [
                (lambda a: ~a[20], ram.bus),
                (lambda a:  a[20], uart.bus)
            ], register=True)

        # work around https://github.com/m-labs/nmigen/issues/30
        m.d.comb += [
            cpu.external_interrupt.eq(0),
            cpu.timer_interrupt.eq(0),
            cpu.fetch.ibus.dat_w.eq(0),
            cpu.fetch.ibus.sel.eq(0b1111),
            cpu.fetch.ibus.we.eq(0),
            cpu.fetch.ibus.cti.eq(0),
            cpu.fetch.ibus.bte.eq(0),
            cpu.loadstore.dbus.cti.eq(0),
            cpu.loadstore.dbus.bte.eq(0),
            ram.bus.err.eq(0),
            uart.bus.err.eq(0),
            uart.bus.dat_r.eq(0)
        ]
        
        return m


def main():
    top = Top()
    output = rtlil.convert(Fragment.get(top, None),
        ports=(top.clk100, top.serial_tx))
    print(output)

if __name__ == "__main__":
    main()