class BinData::IO::Write

See IO::Read for more information.
The IO can handle bitstreams in either big or little endian format.
object.
If io is a string it will be automatically wrapped in an StringIO
Create a new IO Write wrapper around io. io must provide #write.

def flushbits

To be called after all +writebits+ have been applied. 
def flushbits
  raise "Internal state error nbits = #{@wnbits}" if @wnbits >= 8
  if @wnbits > 0
    writebits(0, 8 - @wnbits, @wendian)
  end
end

def initialize(io) 

def initialize(io)
  super(io)
  @wnbits  = 0
  @wval    = 0
  @wendian = nil
end

def mask(nbits) 

def mask(nbits)
  (1 << nbits) - 1
end

def offset

up when writing bitfields.
Returns the current offset of the io stream. Offset will be rounded 
def offset
  offset_raw + (@wnbits > 0 ? 1 : 0)
end

def seekbytes(n)

Seek +n+ bytes from the current position in the io stream. 
def seekbytes(n)
  flushbits
  seek(n)
end

def with_buffer(n)

bytes.
are written inside the block, the remainder will be padded with '\0'
+block+ will be contained within this buffer. If less than +n+ bytes
Sets a buffer of +n+ bytes on the io stream. Any writes inside the 
def with_buffer(n)
  with_buffer_common(n) do |_buf_start, buf_end|
    yield
    write("\0" * (buf_end - offset))
  end
end

def write(data) 

def write(data)
  n = buffer_limited_n(data.size)
  if n < data.size
    data = data[0, n]
  end
  write_raw(data)
end

def write_big_endian_bits(val, nbits) 

def write_big_endian_bits(val, nbits)
  while nbits > 0
    bits_req = 8 - @wnbits
    if nbits >= bits_req
      msb_bits = (val >> (nbits - bits_req)) & mask(bits_req)
      nbits -= bits_req
      val &= mask(nbits)
      @wval   = (@wval << bits_req) | msb_bits
      write(@wval.chr)
      @wval   = 0
      @wnbits = 0
    else
      @wval = (@wval << nbits) | val
      @wnbits += nbits
      nbits = 0
    end
  end
end

def write_little_endian_bits(val, nbits) 

def write_little_endian_bits(val, nbits)
  while nbits > 0
    bits_req = 8 - @wnbits
    if nbits >= bits_req
      lsb_bits = val & mask(bits_req)
      nbits -= bits_req
      val >>= bits_req
      @wval   = @wval | (lsb_bits << @wnbits)
      write(@wval.chr)
      @wval   = 0
      @wnbits = 0
    else
      @wval   = @wval | (val << @wnbits)
      @wnbits += nbits
      nbits = 0
    end
  end
end

def writebits(val, nbits, endian)

the bits are to be stored in +:big+ or +:little+ endian format.
Writes +nbits+ bits from +val+ to the stream. +endian+ specifies whether 
def writebits(val, nbits, endian)
  if @wendian != endian
    # don't mix bits of differing endian
    flushbits
    @wendian = endian
  end
  clamped_val = val & mask(nbits)
  if endian == :big
    write_big_endian_bits(clamped_val, nbits)
  else
    write_little_endian_bits(clamped_val, nbits)
  end
end

def writebytes(str)

Writes the given string of bytes to the io stream. 
def writebytes(str)
  flushbits
  write(str)
end