[geos-commits] [SCM] GEOS branch 3.7 updated. 3e8be5b6f78961093ab7dbb5f404b20746618845

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- Log -----------------------------------------------------------------
commit 3e8be5b6f78961093ab7dbb5f404b20746618845
Author: Paul Ramsey <pramsey at cleverelephant.ca>
Date:   Wed Sep 18 08:45:43 2019 -0700

    Improve the bit-shifting logic with good types and so on
    Even Roualt, Kurt Schwehr
    References #869

diff --git a/src/precision/CommonBits.cpp b/src/precision/CommonBits.cpp
index 547ed5b..f54482d 100644
--- a/src/precision/CommonBits.cpp
+++ b/src/precision/CommonBits.cpp
@@ -43,11 +43,12 @@ CommonBits::numCommonMostSigMantissaBits(int64 num1, int64 num2)
 int64
 CommonBits::zeroLowerBits(int64 bits, int nBits)
 {
-	if (nBits >= 64) return 0;
-	int64 invMask = (1<< nBits)-1;
-	int64 mask = ~ invMask;
-	int64 zeroed = bits & mask;
-	return zeroed;
+	if (nBits >= 64 || nBits < 1) return 0;
+	const uint64_t bits_ = static_cast<uint64_t>(bits);
+	const uint64_t invMask = (1ull << nBits) - 1;
+	const uint64_t mask = ~ invMask;
+	const uint64_t zeroed = bits_ & mask;
+	return static_cast<int64>(zeroed);
 }
 
 /*static public*/
diff --git a/tests/unit/precision/CommonBitsTest.cpp b/tests/unit/precision/CommonBitsTest.cpp
index e3c0bf4..1114074 100644
--- a/tests/unit/precision/CommonBitsTest.cpp
+++ b/tests/unit/precision/CommonBitsTest.cpp
@@ -11,46 +11,69 @@ using geos::precision::CommonBits;
 
 namespace tut
 {
-    // Common data used by tests
-    struct test_commonbits_data {};
-
-    typedef test_group<test_commonbits_data> group;
-    typedef group::object object;
-
-    group test_commonbits_group("geos::precision::CommonBits");
-
-    // getBit from zero.
-    template<>
-    template<>
-    void object::test<1>()
-    {
-        constexpr int64 val = 0ull;
-        for (int i=0; i < 64; i++)
-        {
-            ensure_equals(CommonBits::getBit(val, i), 0);
-        }
-    }
-
-    // getBit from all ones.
-    template<>
-    template<>
-    void object::test<2>()
-    {
-        constexpr int64 val = 0xffffffffffffffffull;
-        for (int i=0; i < 64; i++)
-        {
-            ensure_equals(CommonBits::getBit(val, i), 1);
-        }
-    }
-
-    // getBit check high versus low bits.
-    template<>
-    template<>
-    void object::test<3>()
-    {
-        constexpr int64 val = 0xffffffff00000000ull;
-        ensure_equals(CommonBits::getBit(val, 0), 0);
-        ensure_equals(CommonBits::getBit(val, 63), 1);
-    }
+	// Common data used by tests
+	struct test_commonbits_data {};
+
+	typedef test_group<test_commonbits_data> group;
+	typedef group::object object;
+
+	group test_commonbits_group("geos::precision::CommonBits");
+
+	// getBit from zero.
+	template<>
+	template<>
+	void object::test<1>()
+	{
+		constexpr int64 val = 0ull;
+		for (int i=0; i < 64; i++)
+		{
+			ensure_equals(CommonBits::getBit(val, i), 0);
+		}
+	}
+
+	// getBit from all ones.
+	template<>
+	template<>
+	void object::test<2>()
+	{
+		constexpr int64 val = 0xffffffffffffffffull;
+		for (int i=0; i < 64; i++)
+		{
+			ensure_equals(CommonBits::getBit(val, i), 1);
+		}
+	}
+
+	// getBit check high versus low bits.
+	template<>
+	template<>
+	void object::test<3>()
+	{
+		constexpr int64 val = 0xffffffff00000000ull;
+		ensure_equals(CommonBits::getBit(val, 0), 0);
+		ensure_equals(CommonBits::getBit(val, 63), 1);
+	}
+
+	// zeroLowerBits.
+	template<>
+	template<>
+	void object::test<4>()
+	{
+		constexpr int64 val = static_cast<int64>(0xffffffffffffffffull);
+		ensure_equals(sizeof(val), 8);
+
+		ensure_equals(CommonBits::zeroLowerBits(val, -1), 0);
+		ensure_equals(CommonBits::zeroLowerBits(val, 0), 0);
+		ensure_equals(CommonBits::zeroLowerBits(val, 1), -2);
+		ensure_equals(CommonBits::zeroLowerBits(val, 2), -4);
+		ensure_equals(CommonBits::zeroLowerBits(val, 16), -65536);
+		ensure_equals(CommonBits::zeroLowerBits(val, 31), -2147483648ll);
+		ensure_equals(CommonBits::zeroLowerBits(val, 32), -4294967296ll);
+		ensure_equals(CommonBits::zeroLowerBits(val, 62), -4611686018427387904ll);
+		ensure_equals(static_cast<uint64_t>(CommonBits::zeroLowerBits(val, 62)), 0xc000000000000000ull);
+		ensure_equals(static_cast<uint64_t>(CommonBits::zeroLowerBits(val, 63)), 9223372036854775808ull);
+		ensure_equals(static_cast<uint64_t>(CommonBits::zeroLowerBits(val, 63)), 0x8000000000000000ull);
+		ensure_equals(CommonBits::zeroLowerBits(val, 64), 0);
+		ensure_equals(CommonBits::zeroLowerBits(val, 10000), 0);
+	}
 
 } // namespace tut

-----------------------------------------------------------------------

Summary of changes:
 src/precision/CommonBits.cpp            |  11 ++--
 tests/unit/precision/CommonBitsTest.cpp | 105 +++++++++++++++++++-------------
 2 files changed, 70 insertions(+), 46 deletions(-)


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