#!/bin/env python3
from sys import exit
from time import sleep
from RPi.GPIO import IN, OUT
import RPi.GPIO as GPIO
from re import fullmatch
import argparse
import atexit
# EEPROM AT28C256 Pin names and RPi GPIO Pin Numbers
# b means bar = inverted


gpio_l = [2, 3, 4, 17, 27, 22, 10, 9, 11, 5, 6, 13, 19, 26]
gpio_r = [14, 15, 18, 23, 24, 25, 8, 7, 12, 16, 20, 21]
#
# Defining which 6502 pin goes to which GPIO pin
#

A = [
     # 27, 22, 10, 9, 11, 5, 6, 13,
        13, 6, 5, 11, 9, 10, 22, 27,  # A0 - A7
        3, 4, 18, 17,  # A8 - A11
        23, 2, 15  # A12 - A14
]

IO = [ 16, 20, 21, 12, 7, 8, 25, 24]

OEb = 26    # Output Enable
WEb = 19    # Write Enable
CEb = 14     # Chip Enable is hooked up to A15 on the processor

controls = [CEb, WEb, OEb]

# TIMES
# Read:
t_read_ACC = 150 * 1e-9  # Address to Output Delay
t_read_CE = 70 * 1e-9    # CE to output delay
t_read_OE = 150 * 1e-9   # OE to output delay
t_read_DF = 50 * 1e-9    # data float

# Write:
t_write_AS = 0            # Address Setup time
t_write_OES = 0           # OEb Setup time
t_write_AH = 50 * 1e-9    # Address Hold Time
t_write_CS = 0            # Chip Select Setup Time
t_write_CH = 0            # Chip Select Hold Time
t_write_WP = 100 * 1e-9   # Write Pulse Width
t_write_DS = 50 * 1e-9    # Data Setup Time
t_write_DH = 10 * 1e-9    # Data Hold Time
t_write_OEH = 0           # OEb Hold Time
t_write_WPH = 50 * 1e-9   # Write Puls High
t_write_WC  = 10 * 1e-3   # Write Cycle Time

# t_write_WP = 100 * 1e-6   # Write Pulse Width
# t_write_WPH = 50 * 1e-6   # Write Pulse High !!!2*e5 longer than in Datasheet, since shorter high caused Problems with my Chip!!!
# t_read_ACC = 150 * 1e-6   # Address to Output Delay
# t_write_DH = 1 * 1e-5     # Data Hold Time

# Toggle
t_toggle_OE = 0             # OE to output delay
t_toggle_OEH = 10 * 1e-9    # OE hold time
t_toggle_OEHP = 150 * 1e-9  # OE  high pulse

# t_toggle_OEH = 500 * 1e-7    # OE hold time
# t_toggle_OEHP = 500 * 1e-7  # OE  high pulse

PRINT_HEX = True
PRINT_BIN = False
PRINT_DEC = False
REP_CHAR = '\n'


#
# UTILITY
#
def print_pins():
    for i in range(len(A)):
        print(f" A{i:02} - {A[i]}")
    for i in range(len(IO)):
        print(f"IO{i:02} - {IO[i]}")
    print(f" CEb - {CEb}")
    print(f" WEb - {WEb}")
    print(f" OEb - {OEb}")


def format_number(n, hex_digits=2, bin_digits=8, dec_digits=3, sep=" "):
    s = ""
    if not PRINT_HEX and not PRINT_BIN and not PRINT_DEC:
        print("ERROR: echo: at least one of hex, bin, dec must be set to True")
        exit(1)
    if PRINT_HEX: s += "0x" + format(n, f'0{hex_digits}x') + sep
    if PRINT_BIN: s += "0b" + format(n, f'0{bin_digits}b') + sep
    if PRINT_DEC: s += format(n, f'0{dec_digits}') + sep
    return s[:-len(sep)]


def echo(address: int, value: int, message: str="", mode: str="-", end=None):
    """
    print a message for a given address and value
    """
    s = mode + " " "[" + format_number(address, hex_digits=4, bin_digits=15, dec_digits=5) \
        + "] {" + format_number(value, hex_digits=2, bin_digits=8, dec_digits=3) + "} " \
        + message
    print(s, end=REP_CHAR if end is None else end)


def clear_line():
    print(" " * 80, end='\r')


def convert_to_int(v):
    """
    convert 0xABC and 0b0101 to int
    """
    if type(v) == str and fullmatch(f"0x[0-9,a-f,A-F]+", v):
        return int(v.replace("0x", ""), 16)
    elif type(v) == str and fullmatch(f"0b[0]+", v):
        return int(v.replace("0b", ""), 2)
    return int(v)


def get_n_bits(i: int):
    """
    return how many bits are needed to express the number in binary
    """
    return len(bin(i)) - 2  # -2 for the "0x"


def get_bit(value: int, n: int):
    """
    get the n-th bit (0-based)
    """
    return value & (1 << n)


def read_binary_file(filepath, from_ad=0, to_ad=-1) -> list[int]:
    with open(filepath, "rb") as file:
        bindata = []
        for byte in file.read():
            bindata.append(byte)
    if to_ad < 0:
        to_ad = len(bindata) - 1
    return bindata[from_ad:to_ad+1]


#
# GPIO functions
#
def setup_io_pins(IOdirection=OUT):
     # OUT when writing and IN when reading
    for pin in IO:
        GPIO.setup(pin, IOdirection)

def setup_pins():
    # setup the pins
    GPIO.setmode(GPIO.BCM)
    for pin in controls:
        GPIO.setup(pin, OUT, initial=1)  # inverted, is 1 means disable
    for pin in A:
        GPIO.setup(pin, OUT, initial=0)
    setup_io_pins(IN)




def cleanup():
    GPIO.cleanup()


def set_address(address: int, bits=15):
    """
    set the address pins to the given value
    """
    for j in range(bits):
        GPIO.output(A[j], get_bit(address, j))


def write_byte(byte: int, address: int, verbose=True, debug=False):
    if verbose: echo(address, byte, mode="w")

    GPIO.output(OEb, 1)
    # setup the address
    set_address(address, bits=15)
    GPIO.output(CEb, 0)

    # wait setup time
    sleep(max(t_write_CS, t_write_AS, t_write_OES))
    # Start the write pulse -> enable WEb
    GPIO.output(WEb, 0)

    # Setup Data
    setup_io_pins(OUT)
    for j in range(8):
        GPIO.output(IO[j], get_bit(byte, j))
    sleep(t_write_DS)

    # wait until minimum write pulse width
    sleep(t_write_WP)

    if debug:
        clear_line()
        echo(address, byte, mode="w", message="DEBUG: Press enter to continue")
        input()

    # End Write Pulse -> disable WEb
    GPIO.output(WEb, 1)

    # wait "Data Hold"
    sleep(max(t_write_DH, t_write_WPH))

    GPIO.cleanup(IO)
    setup_io_pins(IN)

    wait_write_finished()
    GPIO.output(CEb, 1)


def write_page(address: int, page: list[int], verbose=True) -> int:
    GPIO.output(OEb, 1)
    # setup the address
    set_address(address, bits=15)
    GPIO.output(CEb, 0)

    echo(address, 0, mode="p")

    assert 64 - (address % 64) >= len(page), f"64 - (address % 64) ={64 - (address % 64)}!>={len(page)}=len(page)"

    # wait setup time
    sleep(max(t_write_CS, t_write_AS, t_write_OES))

    # Setup Data
    setup_io_pins(OUT)

    for i in range(len(page)):
        set_address(address + i, bits=6)
        # Start the write pulse -> enable WEb
        GPIO.output(WEb, 0)

        for j in range(8):
            GPIO.output(IO[j], get_bit(page[i], j))

        sleep(max(t_write_DS, t_write_WP))
        GPIO.output(WEb, 1)
        sleep(t_write_WPH)

    GPIO.cleanup(IO)
    setup_io_pins(IN)

    # wait_write_finished()
    sleep(t_write_WC)

    # print(f"Toggled {timeout} times")
    GPIO.output(CEb, 1)

def wait_write_finished():
    # check the toggle bit IO6, if it stops toggling the write is done
    sleep(t_toggle_OEH)
    timeout = 0
    while timeout < 1e3:
        GPIO.output(OEb, 0)
        sleep(t_toggle_OE)
        bit1 = GPIO.input(IO[6])
        sleep(t_toggle_OEH)
        GPIO.output(OEb, 1)
        sleep(t_toggle_OEHP)
        GPIO.output(OEb, 0)
        sleep(t_toggle_OE)
        bit2 = GPIO.input(IO[6])
        sleep(t_toggle_OEH)
        GPIO.output(OEb, 1)
        sleep(t_toggle_OEHP)
        if bit1 == bit2:
            break
        timeout += 1


def read_byte(address: int, verbose=True, debug=False) -> int:
    GPIO.output(WEb, 1)
    setup_io_pins(IN)
    # set the address valid
    ad_bin = set_address(address, bits=15)

    # low in chip/output enable -> enable
    GPIO.output(CEb, 0)
    GPIO.output(OEb, 0)

    # wait the "Address to Output Delay" until the output is valid
    sleep(max(t_read_ACC, t_read_CE, t_read_OE))

    byte = 0
    for j in range(8):
        byte |= (GPIO.input(IO[j]) << j)

    if debug:
        clear_line()
        echo(address, byte, mode="r", message="DEBUG: Press enter to continue")
        input()

    # high in OEb and CEb -> disable
    GPIO.output(OEb, 1)
    GPIO.output(CEb, 1)

    sleep(t_read_DF)

    if verbose: echo(address, byte, mode="r")

    return byte


#
# FUNCTIONS
#
def read(from_ad=0, to_ad=255, delay=1e-3, ignore=[0xff], debug=False, compare:list[int]=[], verbose=True) -> list[int]:
    """
    from_ad:    start address from where to read
    to_ad:      end address to read to
    delay:      delay between readings in s
    verbose:    wether to print the reading
    ignore:     list of values which are not printed
    """
    content = []
    unequal = []

    if compare:
        assert len(compare) == to_ad - from_ad + 1, f"{len(compare)} vs = {to_ad - from_ad + 1} {to_ad} - {from_ad} + 1"

    for i in range(from_ad, to_ad + 1):
        byte = read_byte(i, verbose=verbose, debug=debug)
        content.append(byte)

        if compare:
            if not compare[i-from_ad] == content[i-from_ad]:
                unequal.append(i)
                echo(i, byte, "vs {" + format_number(compare[i-from_ad], hex_digits=2, bin_digits=8, dec_digits=3) + "} in file", mode="c", end="\n")

        # wait artifical delay
        sleep(delay)
    clear_line()
    if compare:
        return unequal
    return content


def write(content: list[int], from_ad=0, delay=0, debug=False, only_diff=True, verbose=True, check_written=True, use_page_write=False):
    """
    Write a list if bytes to the eeprom.
    WEb controlled
    """
    to_ad = from_ad+len(content)-1
    current_content = []
    if only_diff:
        print(f"Reading EEPROM and only writing deviating values")
        current_content = read(from_ad, to_ad=to_ad, delay=delay, debug=debug, verbose=True)
        assert len(content) == len(current_content)
    failed = []
    print(f"Writing to EEPROM: {len(content)} bytes from address {format(from_ad, '04x')} to {format(to_ad, '04x')}.")

    n_written = 0
    n_written_pages = 0

    if use_page_write:
        # assert from_ad == 0, "from_ad != 0 not supported yet"
        # assert (to_ad+1) % 64 == 0, f"to_ad-1 % 64 != 0 not supported yet. to_ad={to_ad}, to_ad+1% 64 = {(to_ad+1) % 64}"
        for i in range(from_ad, to_ad, 64):
            # print(i, i+64, i+64 - (i%64))
            page_end = i + 64 - (i % 64)
            page = content[i:page_end]
            # print(page, current_content[i:page_end])
            if only_diff and page == current_content[i:page_end]:
                continue
            write_page(i, page)
            n_written_pages += 1
            n_written += len(page)
        sleep(delay)
    else:
        for i in range(from_ad, to_ad + 1):
            if only_diff and (only_diff and content[i-from_ad] != current_content[i-from_ad]):
                continue
            write_byte(content[i-from_ad], i, verbose=True, debug=debug)
            n_written += 1
            # wait artifical delay
            sleep(delay)


    clear_line()
    print(f"Written " + (f"{n_written_pages} pages / " if use_page_write else "") + f"{n_written} bytes")
    if check_written:
        print("Comparing EEPROM to file...")
        failed = read(from_ad=from_ad, to_ad=to_ad, delay=delay, debug=debug, verbose=True, compare=content)
        retries = 2
        while len(failed) > 0 and retries > 0:
            print(f"Found {len(failed)} bytes deviating from the file - retrying: {retries} times")
            for ad in failed:
                write_byte(content[ad-from_ad], ad, verbose=verbose)
            failed = read(from_ad=from_ad, to_ad=to_ad, delay=delay, debug=debug, verbose=False, compare=content)
            retries -= 1
        clear_line()
        print("Comparing complete")
        if len(failed) > 0:
            print(f"Errors occured: {len(failed)} values could not be written:")
            print("[", end="")
            for ad in failed:
                print(format(ad, '04x'), end=",")
            print("]")
    return


def erase(from_ad=0, to_ad=32767, **keys):
    """
    Write all 1 to the EEPROM
    WEb controlled
    """
    data = [0xff for i in range(from_ad, to_ad)]
    write(data, from_ad=from_ad, **keys)
    print("Erased EEPROM - Done!")
    return


def main():
    global REP_CHAR, PRINT_BIN, PRINT_DEC, PRINT_HEX
    parser = argparse.ArgumentParser(
        prog="AT28C256-EEPROM Writer",
        description="Read and write from/to an AT28C256 EEPROM via the Raspberry Pi 4's GPIO pins\n2023 Matthias Quintern",
        epilog="Numbers can be passed as int, hex prefixed with '0x' and binary prefixed with '0b'",
    )
    parser.add_argument("--write", "-w", dest="write", action="store_true", default=False, help="write binary file onto the EEPROM")
    parser.add_argument("--page", "-p", dest="use_page_write", action="store_true", default=False, help="use page write mode")
    parser.add_argument("--no-validate", dest="validate_write", action="store_false", default=True, help="dont validate write operations")
    parser.add_argument("--compare", "-c", dest="compare", action="store_true", default=False, help="compare EEPROM content to binary file")
    parser.add_argument("--read", "-r", dest="read", action="store_true", default=False, help="read the contents of the EEPROM")
    parser.add_argument("--erase", "-e", dest="erase", action="store_true", default=False, help="erase the contents of the EEPROM")
    parser.add_argument("--file", "-f", metavar="file", dest="file", action="store", default="", help="file for --write and --compare")
    parser.add_argument("--from", metavar="start-address", dest="from_ad", action="store", default=0, type=convert_to_int, help="start at address x")
    parser.add_argument("--to", metavar="end-address", dest="to_ad", action="store", default=0x7fff, type=convert_to_int, help="end at address y (inclusive)")
    parser.add_argument("--debug", dest="debug", action="store_true", default=False, help="stop the program after setting up the address")
    parser.add_argument("--delay", dest="delay", metavar="delay", action="store", type=float, default=0.0, help="extra delay between cycles")
    parser.add_argument("--ignore", dest="ignore", metavar="numbers", action="store", nargs="*", type=convert_to_int, default=[0x100], help="ignore the numbers a b ... Default=[0xff]")
    parser.add_argument("--verbose", "-v", dest="verbose", action="store_true", default=False, help="increase verbosity")
    parser.add_argument("--print-pins", dest="print_pins", action="store_true", default=False, help="print the pin layout and exit")
    parser.add_argument("--no-hex", dest="no_hex", action="store_true", default=False, help="Dont print values hex")
    parser.add_argument("--bin", dest="bin", action="store_true", default=False, help="Print values in binary")

    args = parser.parse_args()

    if (args.write or args.compare) and not args.file:
        parser.error('--file is required with --write and --compare')

    if not args.verbose: REP_CHAR = '\r'
    if args.no_hex: PRINT_HEX = False
    if args.bin: PRINT_BIN = True

    if args.file:
        file = read_binary_file(args.file, from_ad=args.from_ad, to_ad=args.to_ad)
        if args.to_ad != args.from_ad + len(file) - 1:
            args.to_ad = args.from_ad + len(file) - 1

    else:
        file = None

    if args.print_pins:
        print_pins()
        exit(0)
    if args.erase:
        erase(from_ad=args.from_ad, to_ad=args.to_ad, delay=args.delay, debug=args.debug, verbose=True)
    if args.write:
        write(file, from_ad=args.from_ad, delay=args.delay, debug=args.debug, verbose=True, check_written=args.validate_write, use_page_write=args.use_page_write)
    if args.read:
        read(from_ad=args.from_ad, to_ad=args.to_ad, delay=args.delay, debug=args.debug, verbose=True, ignore=args.ignore)
    if args.compare:
        unequal = read(from_ad=args.from_ad, to_ad=args.to_ad, delay=args.delay, debug=args.debug, verbose=args.verbose, ignore=args.ignore, compare=file)
        print(f"Found {len(unequal)} deviating values")


if __name__ == '__main__':
    atexit.register(cleanup)
    setup_pins()
    main()

#     PRINT_BIN = True
#     for i in range(15):
#         address = (1 << i)
#         PRINT_BIN = True
#         set_address(address=address)
#         input(f"DEBUG: {format_number(address, hex_digits=4, bin_digits=15)}")