def readFloat16(self):
"""
Read 16-bits from the stream as a float value encoded according to IEEE 754 binary16.
:returns: Read float value.
:raises PythonRuntimeException: If the reading goes behind the stream.
"""
return convertUInt16ToFloat(self.readBits(16))
def testConvertUInt16ToFloat(self):
# plus zero
float16ValuePlusZero = self._createFloat16Value(0, 0, 0) # +0.0
self.assertEqual(0.0, convertUInt16ToFloat(float16ValuePlusZero))
# minus zero
float16ValueMinusZero = self._createFloat16Value(1, 0, 0) # -0.0
self.assertEqual(-0.0, convertUInt16ToFloat(float16ValueMinusZero))
# plus infinity
float16ValuePlusInfinity = self._createFloat16Value(0, 0x1F, 0) # +INF
float64ValuePlusInfinity = self._createFloat64Value(0, 0x7FF,
0) # +INF
convertedFloat = convertUInt16ToFloat(float16ValuePlusInfinity)
self.assertEqual(float64ValuePlusInfinity,
convertFloatToUInt64(convertedFloat))
# minus infinity
float16ValueMinusInfinity = self._createFloat16Value(1, 0x1F,
0) # -INF
float64ValueMinusInfinity = self._createFloat64Value(1, 0x7FF,
0) # -INF
convertedFloat = convertUInt16ToFloat(float16ValueMinusInfinity)
self.assertEqual(float64ValueMinusInfinity,
convertFloatToUInt64(convertedFloat))
# quiet NaN
float16ValueQuietNan = self._createFloat16Value(0, 0x1F, 0x3FF) # +NaN
float64ValueQuietNan = self._createFloat64Value(
0, 0x7FF, 0xFFC0000000000) # +NaN
convertedFloat = convertUInt16ToFloat(float16ValueQuietNan)
self.assertEqual(float64ValueQuietNan,
convertFloatToUInt64(convertedFloat))
# signaling NaN
float16ValueSignalingNan = self._createFloat16Value(1, 0x1F,
0x3FF) # -NaN
float64ValueSignalingNan = self._createFloat64Value(
1, 0x7FF, 0xFFC0000000000) # -NaN
convertedFloat = convertUInt16ToFloat(float16ValueSignalingNan)
self.assertEqual(float64ValueSignalingNan,
convertFloatToUInt64(convertedFloat))
# normal numbers
float16ValueOne = self._createFloat16Value(0, 15, 0) # 1.0
self.assertEqual(1.0, convertUInt16ToFloat(float16ValueOne))
float16ValueOnePlus = self._createFloat16Value(0, 15,
0x01) # 1.0 + 2^-10
float64ValueOnePlus = self._createFloat64Value(
0, 0x3FF, 0x40000000000) # 1.0 + 2^-10
convertedFloat = convertUInt16ToFloat(float16ValueOnePlus)
self.assertEqual(float64ValueOnePlus,
convertFloatToUInt64(convertedFloat))
float16ValueMax = self._createFloat16Value(
0, 30, 0x3FF) # 2^15 (1 + 2^-1 + ... + 2^-10)
self.assertEqual(65504.0, convertUInt16ToFloat(float16ValueMax))
# subnormal numbers
float16ValueMinSubnormal = self._createFloat16Value(0, 0,
1) # 2^-14 (2^-10)
float64ValueMinSubnormal = self._createFloat64Value(0, 999, 0) # 2^-24
convertedFloat = convertUInt16ToFloat(float16ValueMinSubnormal)
self.assertEqual(float64ValueMinSubnormal,
convertFloatToUInt64(convertedFloat))
float16ValueMaxSubnormal = self._createFloat16Value(
0, 0, 0x3FF) # 2^-14 (2^-1 + ... + 2^-10)
float64ValueMaxSubnormal = self._createFloat64Value(
0, 1008, 0xFF80000000000) # 2^-15 (1 + 2^-1 + ... + 2^-9)
convertedFloat = convertUInt16ToFloat(float16ValueMaxSubnormal)
self.assertEqual(float64ValueMaxSubnormal,
convertFloatToUInt64(convertedFloat))