decimal128.py 文件源码

def to_decimal(self):
        """Returns an instance of :class:`decimal.Decimal` for this
        :class:`Decimal128`.
        """
        high = self.__high
        low = self.__low
        sign = 1 if (high & _SIGN) else 0

        if (high & _SNAN) == _SNAN:
            return decimal.Decimal((sign, (), 'N'))
        elif (high & _NAN) == _NAN:
            return decimal.Decimal((sign, (), 'n'))
        elif (high & _INF) == _INF:
            return decimal.Decimal((sign, (0,), 'F'))

        if (high & _EXPONENT_MASK) == _EXPONENT_MASK:
            exponent = ((high & 0x1fffe00000000000) >> 47) - _EXPONENT_BIAS
            return decimal.Decimal((sign, (0,), exponent))
        else:
            exponent = ((high & 0x7fff800000000000) >> 49) - _EXPONENT_BIAS

        arr = bytearray(15)
        mask = 0x00000000000000ff
        for i in range(14, 6, -1):
            arr[i] = (low & mask) >> ((14 - i) << 3)
            mask = mask << 8

        mask = 0x00000000000000ff
        for i in range(6, 0, -1):
            arr[i] = (high & mask) >> ((6 - i) << 3)
            mask = mask << 8

        mask = 0x0001000000000000
        arr[0] = (high & mask) >> 48

        # Have to convert bytearray to bytes for python 2.6.
        digits = [int(digit) for digit in str(_from_bytes(bytes(arr), 'big'))]

        with decimal.localcontext(_DEC128_CTX) as ctx:
            return ctx.create_decimal((sign, digits, exponent))