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# encoding: ascii-8bit
# Copyright 2017 Ball Aerospace & Technologies Corp.
# All Rights Reserved.
#
# This program is free software; you can modify and/or redistribute it
# under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 3 with
# attribution addendums as found in the LICENSE.txt
require 'cosmos/interfaces/protocols/burst_protocol'
require 'cosmos/packet_logs/packet_log_reader'
module Cosmos
# Delineates packets using the COSMOS preidentification system
class PreidentifiedProtocol < BurstProtocol
# @param sync_pattern (see BurstProtocol#initialize)
# @param max_length [Integer] The maximum allowed value of the length field
# @param allow_empty_data [true/false/nil] See Protocol#initialize
def initialize(sync_pattern = nil, max_length = nil, mode = 4, allow_empty_data = nil)
super(0, sync_pattern, false, allow_empty_data)
@max_length = ConfigParser.handle_nil(max_length)
@max_length = Integer(@max_length) if @max_length
@mode = Integer(mode)
end
def reset
super()
@reduction_state = :START
end
def read_packet(packet)
packet.received_time = @read_received_time
packet.target_name = @read_target_name
packet.packet_name = @read_packet_name
if @mode == 4 # COSMOS4.3+ Protocol
packet.stored = @read_stored
packet.extra = @read_extra
end
return packet
end
def write_packet(packet)
received_time = packet.received_time
received_time = Time.now unless received_time
@write_time_seconds = [received_time.tv_sec].pack('N') # UINT32
@write_time_microseconds = [received_time.tv_usec].pack('N') # UINT32
@write_target_name = packet.target_name
@write_target_name = 'UNKNOWN' unless @write_target_name
@write_packet_name = packet.packet_name
@write_packet_name = 'UNKNOWN' unless @write_packet_name
if @mode == 4 # COSMOS4.3+ Protocol
@write_flags = 0
@write_flags |= PacketLogReader::COSMOS4_STORED_FLAG_MASK if packet.stored
@write_extra = nil
if packet.extra
@write_flags |= PacketLogReader::COSMOS4_EXTRA_FLAG_MASK
@write_extra = packet.extra.to_json
end
end
return packet
end
def write_data(data)
data_length = [data.length].pack('N') # UINT32
data_to_send = ''
data_to_send << @sync_pattern if @sync_pattern
if @mode == 4 # COSMOS4.3+ Protocol
data_to_send << @write_flags
if @write_extra
data_to_send << [@write_extra.length].pack('N')
data_to_send << @write_extra
end
end
data_to_send << @write_time_seconds
data_to_send << @write_time_microseconds
data_to_send << @write_target_name.length
data_to_send << @write_target_name
data_to_send << @write_packet_name.length
data_to_send << @write_packet_name
data_to_send << data_length
data_to_send << data
return data_to_send
end
protected
def read_length_field_followed_by_string(length_num_bytes)
# Read bytes for string length
return :STOP if @data.length < length_num_bytes
string_length = @data[0..(length_num_bytes - 1)]
case length_num_bytes
when 1
string_length = string_length.unpack('C')[0] # UINT8
when 2
string_length = string_length.unpack('n')[0] # UINT16
when 4
string_length = string_length.unpack('N')[0] # UINT32
raise "Length value received larger than max_length: #{string_length} > #{@max_length}" if @max_length and string_length > @max_length
else
raise "Unsupported length given to read_length_field_followed_by_string: #{length_num_bytes}"
end
# Read String
return :STOP if @data.length < (string_length + length_num_bytes)
next_index = string_length + length_num_bytes
string = @data[length_num_bytes..(next_index - 1)]
# Remove data from current_data
@data.replace(@data[next_index..-1])
return string
end
def reduce_to_single_packet
# Discard sync pattern if present
if @sync_pattern
if @reduction_state == :START
return :STOP if @data.length < @sync_pattern.length
@data.replace(@data[(@sync_pattern.length)..-1])
@reduction_state = :SYNC_REMOVED
end
elsif @reduction_state == :START
@reduction_state = :SYNC_REMOVED
end
if @reduction_state == :SYNC_REMOVED and @mode == 4
# Read and remove flags
return :STOP if @data.length < 1
flags = @data[0].unpack('C')[0] # byte
@data.replace(@data[1..-1])
@read_stored = false
@read_stored = true if (flags & PacketLogReader::COSMOS4_STORED_FLAG_MASK) != 0
@read_extra = nil
if (flags & PacketLogReader::COSMOS4_EXTRA_FLAG_MASK) != 0
@reduction_state = :NEED_EXTRA
else
@reduction_state = :FLAGS_REMOVED
end
end
if @reduction_state == :NEED_EXTRA
# Read and remove extra
@read_extra = read_length_field_followed_by_string(4)
return :STOP if @read_extra == :STOP
@read_extra = JSON.parse(@read_extra)
@reduction_state = :FLAGS_REMOVED
end
if @reduction_state == :FLAGS_REMOVED or (@reduction_state == :SYNC_REMOVED and @mode != 4)
# Read and remove packet received time
return :STOP if @data.length < 8
time_seconds = @data[0..3].unpack('N')[0] # UINT32
time_microseconds = @data[4..7].unpack('N')[0] # UINT32
@read_received_time = Time.at(time_seconds, time_microseconds).sys
@data.replace(@data[8..-1])
@reduction_state = :TIME_REMOVED
end
if @reduction_state == :TIME_REMOVED
# Read and remove the target name
@read_target_name = read_length_field_followed_by_string(1)
return :STOP if @read_target_name == :STOP
@reduction_state = :TARGET_NAME_REMOVED
end
if @reduction_state == :TARGET_NAME_REMOVED
# Read and remove the packet name
@read_packet_name = read_length_field_followed_by_string(1)
return :STOP if @read_packet_name == :STOP
@reduction_state = :PACKET_NAME_REMOVED
end
if @reduction_state == :PACKET_NAME_REMOVED
# Read packet data and return
packet_data = read_length_field_followed_by_string(4)
return :STOP if packet_data == :STOP
@reduction_state = :START
return packet_data
end
raise "Error should never reach end of method #{@reduction_state}"
end
end
end