Class: JXL::Bit::Reader

Inherits:
Object
  • Object
show all
Defined in:
lib/jxl/bit/reader.rb

Constant Summary collapse

MAX_BITS = 
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Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data, position = 0) ⇒ Reader

Returns a new instance of Reader.



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# File 'lib/jxl/bit/reader.rb', line 10

def initialize(data, position = 0)
  unless position.is_a?(Integer) && position.between?(0, data.bytesize)
    raise ArgumentError, "invalid byte position"
  end

  @data = data.b
  @byte_position = position
  @buffer = 0
  @buffered_bits = 0
  @bits_read = 0
  @overrun = false
end

Instance Attribute Details

#bits_read ⇒ Object (readonly)

Returns the value of attribute bits_read.



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# File 'lib/jxl/bit/reader.rb', line 8

def bits_read
  @bits_read
end

Instance Method Details

#byte_position ⇒ Object 



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# File 'lib/jxl/bit/reader.rb', line 56

def byte_position = @bits_read.div(8)

#close! ⇒ Object

Raises:



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# File 'lib/jxl/bit/reader.rb', line 59

def close!
  raise TruncatedError, "bitstream ended early" if overrun?

  nil
end

#overrun? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/jxl/bit/reader.rb', line 57

def overrun? = @overrun

#peek(bits) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/jxl/bit/reader.rb', line 35

def peek(bits)
  raise ArgumentError, "bit count must be between 0 and #{MAX_BITS}" unless bits.between?(0, MAX_BITS)

  refill while @buffered_bits < bits
  @buffer & ((1 << bits) - 1)
end

#read(bits) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/jxl/bit/reader.rb', line 23

def read(bits)
  raise ArgumentError, "bit count must be between 0 and #{MAX_BITS}" unless bits.between?(0, MAX_BITS)

  refill while @buffered_bits < bits
  value = @buffer & ((1 << bits) - 1)
  @buffer >>= bits
  @buffered_bits -= bits
  @bits_read += bits
  Trace.br(bits, value, @bits_read)
  value
end

#skip(bits) ⇒ Object 



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# File 'lib/jxl/bit/reader.rb', line 42

def skip(bits)
  while bits > MAX_BITS
    read(MAX_BITS)
    bits -= MAX_BITS
  end
  read(bits)
  nil
end

#zero_pad_to_byte ⇒ Object

Raises:



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# File 'lib/jxl/bit/reader.rb', line 51

def zero_pad_to_byte
  padding = (-@bits_read) & 7
  raise CorruptError, "non-zero padding bits" unless read(padding).zero?
end