Class: SwfFile::PackedBitObject

Inherits:
Object
  • Object
show all
Defined in:
lib/swf_file/packed_bit_object.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(bitMarker, byteMarker, decimalValue) ⇒ PackedBitObject

Returns a new instance of PackedBitObject.



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# File 'lib/swf_file/packed_bit_object.rb', line 6

def initialize(bitMarker, byteMarker, decimalValue)
  @nextBitIndex = @bitIndex = bitMarker
  @byteIndex    = byteMarker
  @value        = decimalValue

  if bitMarker <= 7
    @nextBitIndex     += 1
    @nextByteIndex    = byteMarker
    @nextByteBoundary = byteMarker += 1
  else
    @nextBitIndex     = 0
    @nextByteIndex    +=1
    @nextByteBoundary = @nextByteIndex;
  end
end

Instance Attribute Details

#bitIndex ⇒ Object

Returns the value of attribute bitIndex.



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# File 'lib/swf_file/packed_bit_object.rb', line 4

def bitIndex
  @bitIndex
end

#byteIndex ⇒ Object

Returns the value of attribute byteIndex.



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# File 'lib/swf_file/packed_bit_object.rb', line 4

def byteIndex
  @byteIndex
end

#nextBitIndex ⇒ Object

Returns the value of attribute nextBitIndex.



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# File 'lib/swf_file/packed_bit_object.rb', line 4

def nextBitIndex
  @nextBitIndex
end

#nextByteBoundary ⇒ Object

Returns the value of attribute nextByteBoundary.



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# File 'lib/swf_file/packed_bit_object.rb', line 4

def nextByteBoundary
  @nextByteBoundary
end

#nextByteIndex ⇒ Object

Returns the value of attribute nextByteIndex.



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# File 'lib/swf_file/packed_bit_object.rb', line 4

def nextByteIndex
  @nextByteIndex
end

#value ⇒ Object

Returns the value of attribute value.



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# File 'lib/swf_file/packed_bit_object.rb', line 4

def value
  @value
end

Class Method Details

.from_packed_bits(bytes, byte_marker, bit_marker, length) {|pbo| ... } ⇒ Object

Yields:

  • (pbo) 


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# File 'lib/swf_file/packed_bit_object.rb', line 22

def self.from_packed_bits(bytes, byte_marker, bit_marker, length)
  counter     = total = 0
  shift       = 7 - bit_marker
  bit_index   = bit_marker
  byte_index  = byte_marker

  while counter < length
    (bit_marker...8).each do |i|
      bit       = ((bytes[byte_marker].ord & 0xff ) >> shift) & 1
      total     = (total << 1) + bit
      bit_index = i
      shift     -= 1
      counter   += 1

      break if counter == length
    end

    byte_index  = byte_marker
    byte_marker +=1
    bit_marker  = 0
    shift       = 7
  end

  pbo = PackedBitObject.new(bit_index, byte_index, total)
  yield pbo if block_given?
  pbo
end