#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Copyright (C) 2017-2020  The Project X-Ray Authors.
#
# Use of this source code is governed by a ISC-style
# license that can be found in the LICENSE file or at
# https://opensource.org/licenses/ISC
#
# SPDX-License-Identifier: ISC

import sys
import time
import argparse

from litex import RemoteClient

from sdram_init import *


def identify_fpga(wb):
    """ Gets the FPGA identifier and prints it on terminal."""
    fpga_id = ""
    for i in range(256):
        c = chr(wb.read(wb.bases.identifier_mem + 4 * i) & 0xff)
        fpga_id += c
        if c == "\0":
            break
    print(fpga_id)


def seed_to_data(seed, random=True):
    if random:
        return (1664525 * seed + 1013904223) & 0xffffffff
    else:
        return seed


def write_pattern(wb, length):
    for i in range(length):
        wb.write(wb.mems.main_ram.base + 4 * i, seed_to_data(i))


def check_pattern(wb, length, debug=False):
    errors = 0
    for i in range(length):
        error = 0
        if wb.read(wb.mems.main_ram.base + 4 * i) != seed_to_data(i):
            error = 1
            if debug:
                print(
                    "{}: 0x{:08x}, 0x{:08x} KO".format(
                        i, wb.read(wb.mems.main_ram.base + 4 * i),
                        seed_to_data(i)))
        else:
            if debug:
                print(
                    "{}: 0x{:08x}, 0x{:08x} OK".format(
                        i, wb.read(wb.mems.main_ram.base + 4 * i),
                        seed_to_data(i)))
        errors += error
    return errors


def find_bitslips_delays(wb):
    """ Finds bitslip and delay values that can be used with the implemented DDR design."""
    nbitslips = 8
    ndelays = 32
    nmodules = 2
    nwords = 16

    final_bitslip = None
    final_delay = None

    for bitslip in range(nbitslips):
        print("bitslip {:d}: |".format(bitslip), end="")
        for delay in range(ndelays):
            for module in range(nmodules):
                wb.regs.ddrphy_dly_sel.write(1 << module)
                wb.regs.ddrphy_rdly_dq_rst.write(1)
                wb.regs.ddrphy_rdly_dq_bitslip_rst.write(1)
                for i in range(bitslip):
                    wb.regs.ddrphy_rdly_dq_bitslip.write(1)
                for i in range(delay):
                    wb.regs.ddrphy_rdly_dq_inc.write(1)
            write_pattern(wb, nwords)
            errors = check_pattern(wb, nwords)
            if errors:
                print("..|", end="")
            else:
                print("{:02d}|".format(delay), end="")
                final_bitslip = bitslip if final_bitslip is None else final_bitslip
                final_delay = delay if final_delay is None else final_delay
            sys.stdout.flush()
        print("")

    assert final_bitslip is not None and final_delay is not None, "bitslip/delay values not found"

    return final_bitslip, final_delay


def set_bitslip_delay(wb, bitslip, delay):
    """ Sets bitslip and delay values."""
    nmodules = 2

    for module in range(nmodules):
        wb.regs.ddrphy_dly_sel.write(1 << module)
        wb.regs.ddrphy_rdly_dq_rst.write(1)
        wb.regs.ddrphy_rdly_dq_bitslip_rst.write(1)
        for i in range(bitslip):
            wb.regs.ddrphy_rdly_dq_bitslip.write(1)
        for i in range(delay):
            wb.regs.ddrphy_rdly_dq_inc.write(1)


def read_word_offset(read_only=False):
    word = None
    if not read_only:
        print("\n==================================================\n")
        print(
            "Set a byte long word to write to memory (e.g. 0xdeadbeef): ",
            end="")
        word = int(input(), 16) & 0xffffffff

    print("\n==================================================\n")
    print("Set offset from base memory address: ", end="")
    offset = int(input())

    print("\n==================================================\n")
    print("Set number of words to read or write: ", end="")
    length = int(input())

    return word, offset, length


def write_user_pattern(wb, offset, length, pattern):
    for i in range(length):
        wb.write(wb.mems.main_ram.base + 4 * (offset + i), pattern)


def read_user_pattern(wb, offset, length, pattern=None):
    for i in range(length):
        read_value = wb.read(wb.mems.main_ram.base + 4 * (offset + i))

        if pattern is None:
            print("0x{:08x}".format(read_value))
        else:
            if read_value == pattern:
                outcome = "CORRECT"
            else:
                outcome = "INCORRECT"

            print(
                "{} --> 0x{:08x}, 0x{:08x}".format(
                    outcome, read_value, pattern))


def start_command_interface(wb):

    cmd_list = """
Commands list:
    0 --> Write memory
    1 --> Read memory
    2 --> Write/Read memory
    3 --> Print commands list
    4 --> Exit
"""

    print(cmd_list)

    while True:
        print("\nWaiting for command: ", end="")
        cmd = int(input())

        if cmd == 0:
            word, offset, length = read_word_offset()
            write_user_pattern(wb, offset, length, word)
        elif cmd == 1:
            word, offset, length = read_word_offset(True)
            read_user_pattern(wb, offset, length)
        elif cmd == 2:
            word, offset, length = read_word_offset()
            write_user_pattern(wb, offset, length, word)
            read_user_pattern(wb, offset, length, word)
        elif cmd == 3:
            print(cmd_list)
        elif cmd == 4:
            break
        else:
            print("Command not recognized, try again...")


def main():
    parser = argparse.ArgumentParser(
        description="Script to test correct DDR behaviour.")

    parser.add_argument(
        '--bitslip', default=None, help="Defines a bitslip value.")
    parser.add_argument('--delay', default=None, help="Defines a delay value.")

    args = parser.parse_args()

    wb = RemoteClient(debug=False)
    wb.open()

    # software control
    wb.regs.sdram_dfii_control.write(0)

    # sdram initialization
    for i, (comment, a, ba, cmd, delay) in enumerate(init_sequence):
        print(comment)
        wb.regs.sdram_dfii_pi0_address.write(a)
        wb.regs.sdram_dfii_pi0_baddress.write(ba)
        if i < 2:
            wb.regs.sdram_dfii_control.write(cmd)
        else:
            wb.regs.sdram_dfii_pi0_command.write(cmd)
            wb.regs.sdram_dfii_pi0_command_issue.write(1)

    # hardware control
    wb.regs.sdram_dfii_control.write(dfii_control_sel)

    if args.bitslip is None or args.delay is None:
        bitslip, delay = find_bitslips_delays(wb)
    else:
        bitslip = int(args.bitslip)
        delay = int(args.delay)

    set_bitslip_delay(wb, bitslip, delay)

    start_command_interface(wb)

    wb.close()


if __name__ == "__main__":
    main()