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from nordicsemi.dfu import intelhex
from struct import unpack


class nRFHex(intelhex.IntelHex):
    """
        Converts and merges .hex and .bin files into one .bin file.
    """

    info_struct_address_base = 0x00003000
    info_struct_address_offset = 0x1000

    info_struct_magic_number = 0x51B1E5DB
    info_struct_magic_number_offset = 0x004

    s1x0_mbr_end_address = 0x1000
    s132_mbr_end_address = 0x3000

    def __init__(self, source, bootloader=None):
        """
        Constructor that requires a firmware file path.
        Softdevices can take an optional bootloader file path as parameter.

        :param str source: The file path for the firmware
        :param str bootloader: Optional file path to bootloader firmware
        :return: None
        """
        super(nRFHex, self).__init__()

        self.file_format = 'hex'

        if source.endswith('.bin'):
            self.file_format = 'bin'

        self.loadfile(source, self.file_format)

        self._removeuicr()

        self.bootloaderhex = None

        if bootloader is not None:
            self.bootloaderhex = nRFHex(bootloader)

    def _removeuicr(self):
        uicr_start_address = 0x10000000
        maxaddress = self.maxaddr()
        if maxaddress >= uicr_start_address:
            for i in range(uicr_start_address, maxaddress + 1):
                self._buf.pop(i, 0)

    def address_has_magic_number(self, address):
        try:
            potential_magic_number = self.gets(address, 4)
            potential_magic_number = unpack('L', potential_magic_number)[0]
            return nRFHex.info_struct_magic_number == potential_magic_number
        except Exception:
            return False

    def get_softdevice_variant(self):
        potential_magic_number_address = nRFHex.info_struct_address_base + nRFHex.info_struct_magic_number_offset

        if self.address_has_magic_number(potential_magic_number_address):
            return "s1x0"

        for i in xrange(4):
            potential_magic_number_address += nRFHex.info_struct_address_offset

            if self.address_has_magic_number(potential_magic_number_address):
                return "s132"

        return "unknown"

    def get_mbr_end_address(self):
        softdevice_variant = self.get_softdevice_variant()

        if softdevice_variant == "s132":
            return nRFHex.s132_mbr_end_address
        else:
            return nRFHex.s1x0_mbr_end_address

    def minaddr(self):
        min_address = super(nRFHex, self).minaddr()

        # Lower addresses are reserved for master boot record
        if self.file_format != 'bin':
            min_address = max(self.get_mbr_end_address(), min_address)

        return min_address

    def size(self):
        """
        Returns the size of the source.
        :return: int
        """
        min_address = self.minaddr()
        max_address = self.maxaddr()

        size = max_address - min_address + 1

        # Round up to nearest word
        word_size = 4
        number_of_words = (size + (word_size - 1)) / word_size
        size = number_of_words * word_size

        return size

    def bootloadersize(self):
        """
        Returns the size of the bootloader.
        :return: int
        """
        if self.bootloaderhex is None:
            return 0

        return self.bootloaderhex.size()

    def tobinfile(self, fobj, start=None, end=None, pad=None, size=None):
        """
        Writes a binary version of source and bootloader respectivly to fobj which could be a
        file object or a file path.

        :param str fobj: File path or object the function writes to
        :return: None
        """
        # If there is a bootloader this will make the recursion call use the samme file object.
        if getattr(fobj, "write", None) is None:
            fobj = open(fobj, "wb")
            close_fd = True
        else:
            close_fd = False

        start_address = self.minaddr()
        size = self.size()
        super(nRFHex, self).tobinfile(fobj, start=start_address, size=size)

        if self.bootloaderhex is not None:
            self.bootloaderhex.tobinfile(fobj)

        if close_fd:
            fobj.close()