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abacus: bignum: add multiplication

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This commit is contained in:
Bruno BELANYI 2021-08-20 22:19:20 +02:00
parent eb47889eef
commit 4a4b9f361c
3 changed files with 85 additions and 0 deletions
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41
tests/unit/bignum.cc
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@ -156,3 +156,44 @@ TEST(BigNum, substraction_flips_sign) {
EXPECT_EQ(one - two, minus_one);
EXPECT_EQ(minus_one - minus_two, one);
}
TEST(BigNum, multiplication_zero) {
auto const zero = BigNum(0);
auto const one = BigNum(1);
auto const minus_one = BigNum(-1);
EXPECT_EQ(zero * zero, zero);
EXPECT_EQ(zero * one, zero);
EXPECT_EQ(one * zero, zero);
EXPECT_EQ(zero * minus_one, zero);
EXPECT_EQ(minus_one * zero, zero);
}
TEST(BigNum, multiplication_positive) {
auto const one = BigNum(1);
auto const two = BigNum(2);
auto const four = BigNum(4);
EXPECT_EQ(one * one, one);
EXPECT_EQ(two * one, two);
EXPECT_EQ(one * two, two);
EXPECT_EQ(two * two, four);
}
TEST(BigNum, multiplication_mixed_signs) {
auto const minus_one = BigNum(-1);
auto const one = BigNum(1);
auto const minus_two = BigNum(-2);
auto const two = BigNum(2);
auto const minus_four = BigNum(-4);
auto const four = BigNum(4);
EXPECT_EQ(one * minus_one, minus_one);
EXPECT_EQ(minus_one * one, minus_one);
EXPECT_EQ(minus_one * minus_one, one);
EXPECT_EQ(two * minus_one, minus_two);
EXPECT_EQ(minus_one * two, minus_two);
EXPECT_EQ(two * minus_two, minus_four);
EXPECT_EQ(minus_two * two, minus_four);
EXPECT_EQ(minus_two * minus_two, four);
}