import unittest from hypothesis import given from hypothesis.descriptors import integers_in_range, floats_in_range from segpy.portability import byte_string from segpy.ibm_float import (ieee2ibm, ibm2ieee, MAX_IBM_FLOAT, SMALLEST_POSITIVE_NORMAL_IBM_FLOAT, LARGEST_NEGATIVE_NORMAL_IBM_FLOAT, MIN_IBM_FLOAT, IBMFloat, IBM_FLOAT32_EPSILON) from segpy.util import almost_equal class Ibm2Ieee(unittest.TestCase): def test_zero(self): self.assertEqual(ibm2ieee(b'\0\0\0\0'), 0.0) def test_positive_half(self): self.assertEqual(ibm2ieee(byte_string((0b11000000, 0x80, 0x00, 0x00))), -0.5) def test_negative_half(self): self.assertEqual(ibm2ieee(byte_string((0b01000000, 0x80, 0x00, 0x00))), 0.5) def test_one(self): self.assertEqual(ibm2ieee(b'\x41\x10\x00\x00'), 1.0) def test_negative_118_625(self): # Example taken from Wikipedia http://en.wikipedia.org/wiki/IBM_Floating_Point_Architecture self.assertEqual(ibm2ieee(byte_string((0b11000010, 0b01110110, 0b10100000, 0b00000000))), -118.625) def test_largest_representable_number(self): self.assertEqual(ibm2ieee(byte_string((0b01111111, 0b11111111, 0b11111111, 0b11111111))), MAX_IBM_FLOAT) def test_smallest_positive_normalised_number(self): self.assertEqual(ibm2ieee(byte_string((0b00000000, 0b00010000, 0b00000000, 0b00000000))), SMALLEST_POSITIVE_NORMAL_IBM_FLOAT) def test_largest_negative_normalised_number(self): self.assertEqual(ibm2ieee(byte_string((0b10000000, 0b00010000, 0b00000000, 0b00000000))), LARGEST_NEGATIVE_NORMAL_IBM_FLOAT) def test_smallest_representable_number(self): self.assertEqual(ibm2ieee(byte_string((0b11111111, 0b11111111, 0b11111111, 0b11111111))), MIN_IBM_FLOAT) def test_error_1(self): self.assertEqual(ibm2ieee(byte_string((196, 74, 194, 143))), -19138.55859375) def test_error_2(self): self.assertEqual(ibm2ieee(byte_string((191, 128, 0, 0))), -0.03125) def test_subnormal(self): self.assertEqual(ibm2ieee(byte_string((0x00, 0x00, 0x00, 0x20))), 1.6472184286297693e-83) def test_subnormal_is_subnormal(self): self.assertTrue(0 < ibm2ieee(byte_string((0x00, 0x00, 0x00, 0x20))) < SMALLEST_POSITIVE_NORMAL_IBM_FLOAT) def test_subnormal_smallest_subnormal(self): self.assertEqual(ibm2ieee(byte_string((0x00, 0x00, 0x00, 0x01))), 5.147557589468029e-85) class Ieee2Ibm(unittest.TestCase): def test_zero(self): self.assertEqual(ieee2ibm(0.0), b'\0\0\0\0') def test_positive_half(self): self.assertEqual(ieee2ibm(-0.5), byte_string((0b11000000, 0x80, 0x00, 0x00))) def test_negative_half(self): self.assertEqual(ieee2ibm(0.5), byte_string((0b01000000, 0x80, 0x00, 0x00))) def test_one(self): self.assertEqual(ieee2ibm(1.0), b'\x41\x10\x00\x00') def test_negative_118_625(self): # Example taken from Wikipedia http://en.wikipedia.org/wiki/IBM_Floating_Point_Architecture self.assertEqual(ieee2ibm(-118.625), byte_string((0b11000010, 0b01110110, 0b10100000, 0b00000000))) def test_0_1(self): # Note, this is different from the Wikipedia example, because the Wikipedia example does # round to nearest, and our routine does round to zero self.assertEqual(ieee2ibm(0.1), byte_string((0b01000000, 0b00011001, 0b10011001, 0b10011001))) def test_subnormal(self): self.assertEqual(ieee2ibm(1.6472184286297693e-83), byte_string((0x00, 0x00, 0x00, 0x20))) def test_smallest_subnormal(self): self.assertEqual(ieee2ibm(5.147557589468029e-85), byte_string((0x00, 0x00, 0x00, 0x01))) def test_too_small_subnormal(self): with self.assertRaises(FloatingPointError): ieee2ibm(1e-86) def test_nan(self): with self.assertRaises(ValueError): ieee2ibm(float('nan')) def test_inf(self): with self.assertRaises(ValueError): ieee2ibm(float('inf')) def test_too_large(self): with self.assertRaises(OverflowError): ieee2ibm(MAX_IBM_FLOAT * 10) def test_too_small(self): with self.assertRaises(OverflowError): ieee2ibm(MIN_IBM_FLOAT * 10) class Ibm2IeeeRoundtrip(unittest.TestCase): def test_zero(self): ibm_start = b'\0\0\0\0' f = ibm2ieee(ibm_start) ibm_result = ieee2ibm(f) self.assertEqual(ibm_start, ibm_result) def test_positive_half(self): ibm_start = byte_string((0b11000000, 0x80, 0x00, 0x00)) f = ibm2ieee(ibm_start) ibm_result = ieee2ibm(f) self.assertEqual(ibm_start, ibm_result) def test_negative_half(self): ibm_start = byte_string((0b01000000, 0x80, 0x00, 0x00)) f = ibm2ieee(ibm_start) ibm_result = ieee2ibm(f) self.assertEqual(ibm_start, ibm_result) def test_one(self): ibm_start = b'\x41\x10\x00\x00' f = ibm2ieee(ibm_start) ibm_result = ieee2ibm(f) self.assertEqual(ibm_start, ibm_result) def test_subnormal(self): ibm_start = byte_string((0x00, 0x00, 0x00, 0x20)) f = ibm2ieee(ibm_start) ibm_result = ieee2ibm(f) self.assertEqual(ibm_start, ibm_result) class TestIBMFloat(unittest.TestCase): def test_zero_from_float(self): zero = IBMFloat.from_float(0.0) self.assertTrue(zero.is_zero()) def test_zero_from_bytes(self): zero = IBMFloat.from_bytes(b'\x00\x00\x00\x00') self.assertTrue(zero.is_zero()) def test_subnormal(self): ibm = IBMFloat.from_float(1.6472184286297693e-83) self.assertTrue(ibm.is_subnormal()) def test_smallest_subnormal(self): ibm = IBMFloat.from_float(5.147557589468029e-85) self.assertEqual(bytes(ibm), byte_string((0x00, 0x00, 0x00, 0x01))) def test_too_small_subnormal(self): with self.assertRaises(FloatingPointError): IBMFloat.from_float(1e-86) def test_nan(self): with self.assertRaises(ValueError): IBMFloat.from_float(float('nan')) def test_inf(self): with self.assertRaises(ValueError): IBMFloat.from_float(float('inf')) def test_too_large(self): with self.assertRaises(OverflowError): IBMFloat.from_float(MAX_IBM_FLOAT * 10) def test_too_small(self): with self.assertRaises(OverflowError): IBMFloat.from_float(MIN_IBM_FLOAT * 10) @given(float) def test_bool(self, f): self.assertEqual(bool(IBMFloat.from_float(f)), bool(f)) @given(integers_in_range(0, 255), integers_in_range(0, 255), integers_in_range(0, 255), integers_in_range(0, 255)) def test_bytes_roundtrip(self, a, b, c, d): b = byte_string((a, b, c, d)) ibm = IBMFloat.from_bytes(b) self.assertEqual(bytes(ibm), b) @given(floats_in_range(MIN_IBM_FLOAT, MAX_IBM_FLOAT)) def test_floats_roundtrip(self, f): ibm = IBMFloat.from_float(f) self.assertTrue(almost_equal(f, float(ibm), epsilon=IBM_FLOAT32_EPSILON)) if __name__ == '__main__': unittest.main()