Exponential-Golomb coding in hachoir

golomb.py

from hachoir.field import Field


class UExponentialGolomb(Field):
    def __init__(self, parent, name, description=None):
        super(UExponentialGolomb, self).__init__(parent, name, description=description)
        self._zeros = None
        self.determine_size()

    def determine_size(self):
        zeros = 0

        # Find the first 1
        while self._parent.stream.readBits(
            self.absolute_address + zeros,
            1,
            self._parent.endian,
        ) == 0:
            zeros += 1

        self._size = zeros + 1 + zeros
        self._zeros = zeros

    def createValue(self):
        if self._zeros == 0:
            return 0
        
        data = self._parent.stream.readBits(
                self.absolute_address + self._zeros,
                self._zeros + 1,
                self._parent.endian,
            )
        return data - 1

    def createRawDisplay(self):
        return str(int(self.value))

    def hasValue(self):
        return True