source: ammosreader/ammosreader/AmmosIFReader.py@ 87b2e39

"""I provide a specialized Ammos Reader for IF data."""

from ammosreader.AmmosGlobalFrameBody import AmmosGlobalFrameBody
from ammosreader.AmmosIFDataHeader import AmmosIFDataHeader
from ammosreader.AmmosExtendedIFDataHeader import AmmosExtendedIFDataHeader
from ammosreader.AmmosGlobalFrameHeader import AmmosGlobalFrameHeader
from ammosreader.AmmosSingleFrame import AmmosSingleFrame
from ammosreader.AmmosIFDataBlock import AmmosIFDataBlock
from ammosreader.AmmosContainer import AmmosContainer


class AmmosIFReader():

    STANDARD_IF_DATA_HEADER_SIZE = 56
    EXTENDED_IF_DATA_HEADER_SIZE = 76

    def __init__(self, file_name):
        super.__init__(file_name)

    def read_next_global_frame_body_data_header(self):

        bytes = self.ammos_file.read(AmmosIFReader.STANDARD_IF_DATA_HEADER_SIZE)

        # print("\nReading global frame body standard data header\n")
        if ((not bytes) or (len(bytes) < AmmosIFReader.STANDARD_IF_DATA_HEADER_SIZE)):
            # print("Can not read all 56 bytes of global frame body data header")
            return None

        data_header = AmmosIFDataHeader.from_bytes(bytes)
        # print("Data header", data_header)
        return data_header

    def read_next_global_frame_body_extended_data_header(self):

        bytes = self.ammos_file.read(AmmosIFReader.EXTENDED_IF_DATA_HEADER_SIZE)
        # print("\nReading global frame body extended data header\n")

        if ((not bytes) or (len(bytes) < AmmosIFReader.EXTENDED_IF_DATA_HEADER_SIZE)):
            # print("Can not read all ", 76, "bytes of global frame extended data header")
            return None
        extended_data_header = AmmosExtendedIFDataHeader.from_bytes(bytes)
        # print("Extended data header", extended_data_header)
        return extended_data_header

    def read_next_if_data_blocks(self, n, length):

        # FIXME: Describe the parameters better

        data_blocks = []

        block_length = 4 + length

        total = n*block_length

        byte_string = self.ammos_file.read(block_length)

        if len(byte_string) != total:
            # print("Can not read all", total, "bytes of data body")
            return None

        for i in range(0, n):
            result = byte_string[i*block_length:(i*block_length+block_length)]
            data_blocks.append(AmmosIFDataBlock(result[0:4], result[4:]))

        return data_blocks

    def read_next_global_frame_body(self, data_header_length):

        if_data_header = None

        if data_header_length == AmmosIFReader.STANDARD_IF_DATA_HEADER_SIZE:
            if_data_header = self.read_next_global_frame_body_data_header()
        if data_header_length == AmmosIFReader.EXTENDED_IF_DATA_HEADER_SIZE:
            if_data_header = self.read_next_global_frame_body_extended_data_header()

        if if_data_header is None:
            # print("Data header missing")
            return None

        if_data_body = self.read_next_if_data_blocks(if_data_header.block_count, if_data_header.block_length)

        if if_data_body is None:
            # print("Data body missing")
            return None

        return AmmosGlobalFrameBody(if_data_header, if_data_body)