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require 'bit-struct/char-field'
class BitStruct
# Class for char fields that can be accessed with values like
# "xxx.xxx.xxx.xxx", where each xxx is up to 3 decimal digits representing a
# single octet. The original string-based accessors are still available with
# the <tt>_chars</tt> suffix.
#
# Declared with BitStruct.octets.
class OctetField < BitStruct::CharField
# Used in describe.
def self.class_name
@class_name ||= "octets"
end
SEPARATOR = "."
FORMAT = "%d"
BASE = 10
def add_accessors_to(cl, attr = name) # :nodoc:
attr_chars = "#{attr}_chars"
super(cl, attr_chars)
sep = self.class::SEPARATOR
base = self.class::BASE
fmt = self.class::FORMAT
cl.class_eval do
define_method attr do ||
ary = []
send(attr_chars).each_byte do |c|
ary << fmt % c
end
ary.join(sep)
end
old_writer = "#{attr_chars}="
define_method "#{attr}=" do |val|
data = val.split(sep).map{|s|s.to_i(base)}.pack("c*")
send(old_writer, data)
end
end
end
end
class << self
# Define an octet string field in the current subclass of BitStruct,
# with the given _name_ and _length_ (in bits). Trailing nulls are
# not considered part of the string. The field is accessed using
# period-separated decimal digits.
#
# If a class is provided, use it for the Field class.
# If a string is provided, use it for the display_name.
# If a hash is provided, use it for options.
#
def octets(name, length, *rest)
opts = parse_options(rest, name, OctetField)
add_field(name, length, opts)
end
end
end
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