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src/test/intmath_tests.cpp

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// Copyright (c) 2021 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <boost/test/unit_test.hpp>
#include <test/lcg.h>
#include <test/util/setup_common.h>
#include <script/intmath.h>
#include <boost/multiprecision/cpp_int.hpp>
BOOST_FIXTURE_TEST_SUITE(intmath_tests, BasicTestingSetup)
typedef boost::multiprecision::checked_int128_t i128_t;
const i128_t MAX_SCRIPT_63_BIT_INT = 0x7fff'ffff'ffff'ffff;
const i128_t MIN_SCRIPT_63_BIT_INT = -0x7fff'ffff'ffff'ffff;
const static std::vector<int64_t> INTERESTING_63_BIT_NUMBERS({
0,
1,
-1,
2,
-2,
4,
-4,
10,
-10,
100,
-100,
127,
-127,
255,
-255,
256,
-256,
1000,
-1000,
5040,
-5040,
0x7fff,
-0x7fff,
0x1'0000,
-0x1'0000,
0x7f'ffff,
-0x7f'ffff,
0x100'0000,
-0x100'0000,
0x7fff'ffff,
-0x7fff'ffff,
0xffff'ffff,
-0xffff'ffff,
0x1'0000'0000,
-0x1'0000'0000,
0x7f'ffff'ffff,
-0x7f'ffff'ffff,
0xff'ffff'ffff,
-0xff'ffff'ffff,
0x100'0000'0000,
-0x100'0000'0000,
0x7fff'ffff'ffff,
-0x7fff'ffff'ffff,
0xffff'ffff'ffff,
-0xffff'ffff'ffff,
0x1'0000'0000'0000,
-0x1'0000'0000'0000,
0x7f'ffff'ffff'ffff,
-0x7f'ffff'ffff'ffff,
0xff'ffff'ffff'ffff,
-0xff'ffff'ffff'ffff,
0x100'0000'0000'0000,
-0x100'0000'0000'0000,
0x7fff'ffff'ffff'ffff,
-0x7fff'ffff'ffff'ffff,
});
bool IsInScriptBounds(const i128_t &num_int) {
return num_int >= MIN_SCRIPT_63_BIT_INT && num_int <= MAX_SCRIPT_63_BIT_INT;
}
void CheckArithmetic(const int64_t a_64, const int64_t b_64) {
const i128_t a = a_64;
const i128_t b = b_64;
{
// Test AddInt63OverflowEmulated
int64_t result;
bool expect_overflow = !IsInScriptBounds(a + b);
bool had_overflow = AddInt63OverflowEmulated(a_64, b_64, result);
if (expect_overflow) {
BOOST_CHECK_MESSAGE(
had_overflow, strprintf("%d + %d didn't overflow", a_64, b_64));
} else {
BOOST_CHECK_MESSAGE(!had_overflow,
strprintf("%d + %d overflowed", a_64, b_64));
BOOST_CHECK_EQUAL(result, a + b);
}
}
{
// Test SubInt63OverflowEmulated
int64_t result;
bool expect_overflow = !IsInScriptBounds(a - b);
bool had_overflow = SubInt63OverflowEmulated(a_64, b_64, result);
if (expect_overflow) {
BOOST_CHECK_MESSAGE(
had_overflow, strprintf("%d - %d didn't overflow", a_64, b_64));
} else {
BOOST_CHECK_MESSAGE(!had_overflow,
strprintf("%d - %d overflowed", a_64, b_64));
BOOST_CHECK_EQUAL(result, a - b);
}
}
}
/** Generate random number in [-2^63; 2^63]. */
int64_t GenInt63(MMIXLinearCongruentialGenerator &lcg) {
while (true) {
// Uniform number in [-2^63; 2^63].
int64_t val = (int64_t(lcg.next()) << 32) | lcg.next();
// Make bit-length uniformly distributed for better test coverage.
val >>= (lcg.next() % 64);
// Ensure value is in bounds.
if (val != std::numeric_limits<int64_t>::min()) {
return val;
}
}
}
BOOST_AUTO_TEST_CASE(check_arithmetic) {
MMIXLinearCongruentialGenerator lcg;
for (uint32_t test = 0; test < 2048; ++test) {
int64_t a = GenInt63(lcg);
int64_t b = GenInt63(lcg);
CheckArithmetic(a, b);
for (const int64_t &num : INTERESTING_63_BIT_NUMBERS) {
CheckArithmetic(a, num);
CheckArithmetic(num, b);
}
}
for (const int64_t &a : INTERESTING_63_BIT_NUMBERS) {
for (const int64_t &b : INTERESTING_63_BIT_NUMBERS) {
CheckArithmetic(a, b);
}
}
}
BOOST_AUTO_TEST_SUITE_END()