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Diffstat (limited to 'src/test/serfloat_tests.cpp')
| -rw-r--r-- | src/test/serfloat_tests.cpp | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/src/test/serfloat_tests.cpp b/src/test/serfloat_tests.cpp new file mode 100644 index 0000000000..54e07b0f61 --- /dev/null +++ b/src/test/serfloat_tests.cpp @@ -0,0 +1,129 @@ +// Copyright (c) 2014-2020 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include <hash.h> +#include <test/util/setup_common.h> +#include <util/serfloat.h> +#include <serialize.h> +#include <streams.h> + +#include <boost/test/unit_test.hpp> + +#include <cmath> +#include <limits> + +BOOST_FIXTURE_TEST_SUITE(serfloat_tests, BasicTestingSetup) + +namespace { + +uint64_t TestDouble(double f) { + uint64_t i = EncodeDouble(f); + double f2 = DecodeDouble(i); + if (std::isnan(f)) { + // NaN is not guaranteed to round-trip exactly. + BOOST_CHECK(std::isnan(f2)); + } else { + // Everything else is. + BOOST_CHECK(!std::isnan(f2)); + uint64_t i2 = EncodeDouble(f2); + BOOST_CHECK_EQUAL(f, f2); + BOOST_CHECK_EQUAL(i, i2); + } + return i; +} + +} // namespace + +BOOST_AUTO_TEST_CASE(double_serfloat_tests) { + BOOST_CHECK_EQUAL(TestDouble(0.0), 0); + BOOST_CHECK_EQUAL(TestDouble(-0.0), 0x8000000000000000); + BOOST_CHECK_EQUAL(TestDouble(std::numeric_limits<double>::infinity()), 0x7ff0000000000000); + BOOST_CHECK_EQUAL(TestDouble(-std::numeric_limits<double>::infinity()), 0xfff0000000000000); + BOOST_CHECK_EQUAL(TestDouble(0.5), 0x3fe0000000000000ULL); + BOOST_CHECK_EQUAL(TestDouble(1.0), 0x3ff0000000000000ULL); + BOOST_CHECK_EQUAL(TestDouble(2.0), 0x4000000000000000ULL); + BOOST_CHECK_EQUAL(TestDouble(4.0), 0x4010000000000000ULL); + BOOST_CHECK_EQUAL(TestDouble(785.066650390625), 0x4088888880000000ULL); + + // Roundtrip test on IEC559-compatible systems + if (std::numeric_limits<double>::is_iec559) { + BOOST_CHECK_EQUAL(sizeof(double), 8); + BOOST_CHECK_EQUAL(sizeof(uint64_t), 8); + // Test extreme values + TestDouble(std::numeric_limits<double>::min()); + TestDouble(-std::numeric_limits<double>::min()); + TestDouble(std::numeric_limits<double>::max()); + TestDouble(-std::numeric_limits<double>::max()); + TestDouble(std::numeric_limits<double>::lowest()); + TestDouble(-std::numeric_limits<double>::lowest()); + TestDouble(std::numeric_limits<double>::quiet_NaN()); + TestDouble(-std::numeric_limits<double>::quiet_NaN()); + TestDouble(std::numeric_limits<double>::signaling_NaN()); + TestDouble(-std::numeric_limits<double>::signaling_NaN()); + TestDouble(std::numeric_limits<double>::denorm_min()); + TestDouble(-std::numeric_limits<double>::denorm_min()); + // Test exact encoding: on currently supported platforms, EncodeDouble + // should produce exactly the same as the in-memory representation for non-NaN. + for (int j = 0; j < 1000; ++j) { + // Iterate over 9 specific bits exhaustively; the others are chosen randomly. + // These specific bits are the sign bit, and the 2 top and bottom bits of + // exponent and mantissa in the IEEE754 binary64 format. + for (int x = 0; x < 512; ++x) { + uint64_t v = InsecureRandBits(64); + v &= ~(uint64_t{1} << 0); + if (x & 1) v |= (uint64_t{1} << 0); + v &= ~(uint64_t{1} << 1); + if (x & 2) v |= (uint64_t{1} << 1); + v &= ~(uint64_t{1} << 50); + if (x & 4) v |= (uint64_t{1} << 50); + v &= ~(uint64_t{1} << 51); + if (x & 8) v |= (uint64_t{1} << 51); + v &= ~(uint64_t{1} << 52); + if (x & 16) v |= (uint64_t{1} << 52); + v &= ~(uint64_t{1} << 53); + if (x & 32) v |= (uint64_t{1} << 53); + v &= ~(uint64_t{1} << 61); + if (x & 64) v |= (uint64_t{1} << 61); + v &= ~(uint64_t{1} << 62); + if (x & 128) v |= (uint64_t{1} << 62); + v &= ~(uint64_t{1} << 63); + if (x & 256) v |= (uint64_t{1} << 63); + double f; + memcpy(&f, &v, 8); + uint64_t v2 = TestDouble(f); + if (!std::isnan(f)) BOOST_CHECK_EQUAL(v, v2); + } + } + } +} + +/* +Python code to generate the below hashes: + + def reversed_hex(x): + return binascii.hexlify(''.join(reversed(x))) + def dsha256(x): + return hashlib.sha256(hashlib.sha256(x).digest()).digest() + + reversed_hex(dsha256(''.join(struct.pack('<d', x) for x in range(0,1000)))) == '43d0c82591953c4eafe114590d392676a01585d25b25d433557f0d7878b23f96' +*/ +BOOST_AUTO_TEST_CASE(doubles) +{ + CDataStream ss(SER_DISK, 0); + // encode + for (int i = 0; i < 1000; i++) { + ss << EncodeDouble(i); + } + BOOST_CHECK(Hash(ss) == uint256S("43d0c82591953c4eafe114590d392676a01585d25b25d433557f0d7878b23f96")); + + // decode + for (int i = 0; i < 1000; i++) { + uint64_t val; + ss >> val; + double j = DecodeDouble(val); + BOOST_CHECK_MESSAGE(i == j, "decoded:" << j << " expected:" << i); + } +} + +BOOST_AUTO_TEST_SUITE_END() |