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require 'bindata/base_primitive'
module BinData
# Resets the stream alignment to the next byte. This is
# only useful when using bit-based primitives.
#
# class MyRec < BinData::Record
# bit4 :a
# resume_byte_alignment
# bit4 :b
# end
#
# MyRec.read("\x12\x34") #=> {"a" => 1, "b" => 3}
#
class ResumeByteAlignment < BinData::Base
def clear?; true; end
def assign(val); end
def snapshot; nil; end
def do_num_bytes; 0; end
def do_read(io)
io.reset_read_bits
end
def do_write(io)
io.flushbits
end
end
# A monkey patch to force byte-aligned primitives to
# become bit-aligned. This allows them to be used at
# non byte based boundaries.
#
# class BitString < BinData::String
# bit_aligned
# end
#
# class MyRecord < BinData::Record
# bit4 :preamble
# bit_string :str, length: 2
# end
#
module BitAligned
class BitAlignedIO
def initialize(io)
@io = io
end
def readbytes(n)
n.times.inject("") do |bytes, _|
bytes += @io.readbits(8, :big).chr
end
end
end
def bit_aligned?
true
end
def read_and_return_value(io)
super(BitAlignedIO.new(io))
end
def do_num_bytes
super.to_f
end
def do_write(io)
value_to_binary_string(_value).each_byte { |v| io.writebits(v, 8, :big) }
end
end
def BasePrimitive.bit_aligned
include BitAligned
end
def Primitive.bit_aligned
fail "'bit_aligned' is not needed for BinData::Primitives"
end
end
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