Permalink
Fetching contributors…
Cannot retrieve contributors at this time
184 lines (167 sloc) 6.33 KB
# 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/config/config_parser'
require 'cosmos/interfaces/protocols/protocol'
require 'cosmos/utilities/crc'
require 'thread'
module Cosmos
# Creates a CRC on write and verifies a CRC on read
class CrcProtocol < Protocol
ERROR = "ERROR" # on CRC mismatch
DISCONNECT = "DISCONNECT" # on CRC mismatch
# @param write_item_name [String/nil] Item to fill with calculated CRC value for outgoing packets (nil = don't fill)
# @param strip_crc [Boolean] Whether or not to remove the CRC from incoming packets
# @param bad_strategy [ERROR/DISCONNECT] How to handle CRC errors on incoming packets. ERROR = Just log the error, DISCONNECT = Disconnect interface
# @param bit_offset [Integer] Bit offset of the CRC in the data. Can be negative to indicate distance from end of packet
# @param bit_size [Integer] Bit size of the CRC - Must be 16, 32, or 64
# @param endianness [BIG_ENDIAN/LITTLE_ENDIAN] Endianness of the CRC
# @param poly [Integer] Polynomial to use when calculating the CRC
# @param seed [Integer] Seed value to start the calculation
# @param xor [Boolean] Whether to XOR the CRC result with 0xFFFF
# @param reflect [Boolean] Whether to bit reverse each byte of data before calculating the CRC
# @param allow_empty_data [true/false/nil] See Protocol#initialize
def initialize(
write_item_name = nil,
strip_crc = false,
bad_strategy = "ERROR",
bit_offset = -32,
bit_size = 32,
endianness = 'BIG_ENDIAN',
poly = nil,
seed = nil,
xor = nil,
reflect = nil,
allow_empty_data = nil
)
super(allow_empty_data)
@write_item_name = ConfigParser.handle_nil(write_item_name)
@strip_crc = ConfigParser.handle_true_false(strip_crc)
raise "Invalid strip CRC of '#{strip_crc}'. Must be TRUE or FALSE." unless !!@strip_crc == @strip_crc
case bad_strategy
when ERROR, DISCONNECT
@bad_strategy = bad_strategy
else
raise "Invalid bad CRC strategy of #{bad_strategy}. Must be ERROR or DISCONNECT."
end
case endianness.to_s.upcase
when 'BIG_ENDIAN'
@endianness = :BIG_ENDIAN # Convert to symbol for use in BinaryAccessor.write
when 'LITTLE_ENDIAN'
@endianness = :LITTLE_ENDIAN # Convert to symbol for use in BinaryAccessor.write
else
raise "Invalid endianness '#{endianness}'. Must be BIG_ENDIAN or LITTLE_ENDIAN."
end
begin
@bit_offset = Integer(bit_offset)
rescue
raise "Invalid bit offset of #{bit_offset}. Must be a number."
end
raise "Invalid bit offset of #{bit_offset}. Must be divisible by 8." if @bit_offset % 8 != 0
poly = ConfigParser.handle_nil(poly)
begin
poly = Integer(poly) if poly
rescue
raise "Invalid polynomial of #{poly}. Must be a number."
end
seed = ConfigParser.handle_nil(seed)
begin
seed = Integer(seed) if seed
rescue
raise "Invalid seed of #{seed}. Must be a number."
end
xor = ConfigParser.handle_true_false_nil(xor)
raise "Invalid XOR value of '#{xor}'. Must be TRUE or FALSE." if xor && !!xor != xor
reflect = ConfigParser.handle_true_false_nil(reflect) if reflect
raise "Invalid reflect value of '#{reflect}'. Must be TRUE or FALSE." if reflect && !!reflect != reflect
# Built the CRC arguments array. All subsequent arguments are dependent
# on the previous ones so we build it up incrementally.
args = []
if poly
args << poly
if seed
args << seed
unless xor.nil? # Can't check raw variable because it could be false
args << xor
unless reflect.nil? # Can't check raw variable because it could be false
args << reflect
end
end
end
end
@bit_size = bit_size.to_i
case @bit_size
when 16
@pack = (@endianness == :BIG_ENDIAN) ? 'n' : 'v'
if args.empty?
@crc = Crc16.new
else
@crc = Crc16.new(*args)
end
when 32
@pack = (@endianness == :BIG_ENDIAN) ? 'N' : 'V'
if args.empty?
@crc = Crc32.new
else
@crc = Crc32.new(*args)
end
when 64
@pack = (@endianness == :BIG_ENDIAN) ? 'N' : 'V'
if args.empty?
@crc = Crc64.new
else
@crc = Crc64.new(*args)
end
else
raise "Invalid bit size of #{bit_size}. Must be 16, 32, or 64."
end
end
def read_data(data)
return super(data) if (data.length <= 0)
crc = BinaryAccessor.read(@bit_offset, @bit_size, :UINT, data, @endianness)
calculated_crc = @crc.calc(data[0...(@bit_offset / 8)])
if calculated_crc != crc
Logger.error "Invalid CRC detected! Calculated 0x#{calculated_crc.to_s(16).upcase} vs found 0x#{crc.to_s(16).upcase}."
if @bad_strategy == DISCONNECT
return :DISCONNECT
end
end
if @strip_crc
new_data = data.dup
new_data = new_data[0...(@bit_offset / 8)]
end_range = (@bit_offset + @bit_size) / 8
new_data << data[end_range..-1] if end_range != 0
return new_data
end
return data
end
def write_packet(packet)
if @write_item_name
end_range = packet.get_item(@write_item_name).bit_offset / 8
crc = @crc.calc(packet.buffer(false)[0...end_range])
packet.write(@write_item_name, crc)
end
packet
end
def write_data(data)
unless @write_item_name
if @bit_size == 64
crc = @crc.calc(data)
data << ("\x00" * 8)
BinaryAccessor.write((crc >> 32), -64, 32, :UINT, data, @endianness, :ERROR)
BinaryAccessor.write((crc & 0xFFFFFFFF), -32, 32, :UINT, data, @endianness, :ERROR)
else
crc = @crc.calc(data)
data << ("\x00" * (@bit_size / 8))
BinaryAccessor.write(crc, -@bit_size, @bit_size, :UINT, data, @endianness, :ERROR)
end
end
data
end
end
end