LibJS+LibCrypto: Fix SignedBitInteger::bitwise_not and use it in LibJS

Bitwise operators are defined on two's complement, but SignedBitInteger
uses sign-magnitude. Correctly convert between the two.

Let LibJS delegate to SignedBitInteger for bitwise_not, like it does
for all other bitwise_ operations on bigints.

No behavior change (LibJS is now the only client of
SignedBitInteger::bitwise_not()).

1 files changed, 6 insertions, 0 deletions

diff --git a/Tests/LibCrypto/TestBigInteger.cpp b/Tests/LibCrypto/TestBigInteger.cpp
index 504fb4eab1..16cf58ae8c 100644
--- a/Tests/LibCrypto/TestBigInteger.cpp
+++ b/Tests/LibCrypto/TestBigInteger.cpp
@@ -467,6 +467,12 @@ TEST_CASE(test_bigint_bitwise_and_different_lengths)
     EXPECT_EQ(num1.bitwise_and(num2), "1180290"_bigint);
 }
 
+TEST_CASE(test_signed_bigint_bitwise_not)
+{
+    EXPECT_EQ("3"_sbigint.bitwise_not(), "-4"_sbigint);
+    EXPECT_EQ("-1"_sbigint.bitwise_not(), "0"_sbigint);
+}
+
 TEST_CASE(test_signed_bigint_bitwise_and)
 {
     auto num1 = "-1234567"_sbigint;