core: implement shift operators for reals; they're useful for fast

multiplications by integers, especially powers of two.

src/real.cpp

@@ -350,6 +350,32 @@ real &real::operator /=(real const &x)
     return *this = tmp / x;
 }
 
+real real::operator <<(int x) const
+{
+    real tmp = *this;
+    return tmp <<= x;
+}
+
+real real::operator >>(int x) const
+{
+    real tmp = *this;
+    return tmp >>= x;
+}
+
+real &real::operator <<=(int x)
+{
+    if (m_signexp << 1)
+        m_signexp += x;
+    return *this;
+}
+
+real &real::operator >>=(int x)
+{
+    if (m_signexp << 1)
+        m_signexp -= x;
+    return *this;
+}
+
 bool real::operator ==(real const &x) const
 {
     if ((m_signexp << 1) == 0 && (x.m_signexp << 1) == 0)
@@ -541,9 +567,7 @@ static real fastlog(real const &x)
         zn *= z2;
     }
 
-    /* FIXME: sum.m_signexp += 2; (but needs private data access) */
-    sum *= (real)4;
-    return z * sum;
+    return z * (sum << 2);
 }
 
 static real LOG_2 = fastlog((real)2);

src/real.h

@@ -46,6 +46,11 @@ public:
     real &operator *=(real const &x);
     real &operator /=(real const &x);
 
+    real operator <<(int x) const;
+    real operator >>(int x) const;
+    real &operator <<=(int x);
+    real &operator >>=(int x);
+
     bool operator ==(real const &x) const;
     bool operator !=(real const &x) const;
     bool operator <(real const &x) const;

test/unit/real.cpp

@@ -69,7 +69,7 @@ LOLUNIT_FIXTURE(RealTest)
         LOLUNIT_ASSERT_EQUAL(a4, 0.0f);
     }
 
-    LOLUNIT_TEST(RealComparison)
+    LOLUNIT_TEST(Comparison)
     {
         LOLUNIT_ASSERT(real(1.0f) > real(0.5f));
         LOLUNIT_ASSERT(real(1.0f) >= real(0.5f));
@@ -90,7 +90,7 @@ LOLUNIT_FIXTURE(RealTest)
         LOLUNIT_ASSERT(real(0.5f) >= real(-1.0f));
     }
 
-    LOLUNIT_TEST(RealAddition)
+    LOLUNIT_TEST(Addition)
     {
         float a1 = real(1.0f) + real(0.0f);
         float a2 = real(0.0f) + real(1.0f);
@@ -112,14 +112,14 @@ LOLUNIT_FIXTURE(RealTest)
         LOLUNIT_ASSERT_DOUBLES_EQUAL(a8, 0.1, 1.0e-13);
     }
 
-    LOLUNIT_TEST(RealSubtraction)
+    LOLUNIT_TEST(Subtraction)
     {
         float a1 = real(1.0f) + real(1e20f) - real(1e20f);
 
         LOLUNIT_ASSERT_EQUAL(a1, 1.0f);
     }
 
-    LOLUNIT_TEST(RealMultiplication)
+    LOLUNIT_TEST(Multiplication)
     {
         real x(1.25f);
         real y(1.5f);
@@ -137,7 +137,7 @@ LOLUNIT_FIXTURE(RealTest)
         LOLUNIT_ASSERT_EQUAL(m4, -1.5f * -1.5f);
     }
 
-    LOLUNIT_TEST(RealDivision)
+    LOLUNIT_TEST(Division)
     {
         real a1(1.0f);
         real a2(2.0f);
@@ -154,6 +154,28 @@ LOLUNIT_FIXTURE(RealTest)
         LOLUNIT_ASSERT_EQUAL(m4, 1.0f);
         LOLUNIT_ASSERT_EQUAL(m5, -0.5f);
     }
+
+    LOLUNIT_TEST(Shift)
+    {
+        real a1(1.5);
+        real a2(-1.5);
+        real a3(0.0);
+
+        LOLUNIT_ASSERT_EQUAL((double)(a1 >> 7), 0.01171875);
+        LOLUNIT_ASSERT_EQUAL((double)(a1 >> -7), 192.0);
+        LOLUNIT_ASSERT_EQUAL((double)(a1 << 7), 192.0);
+        LOLUNIT_ASSERT_EQUAL((double)(a1 << -7), 0.01171875);
+
+        LOLUNIT_ASSERT_EQUAL((double)(a2 >> 7), -0.01171875);
+        LOLUNIT_ASSERT_EQUAL((double)(a2 >> -7), -192.0);
+        LOLUNIT_ASSERT_EQUAL((double)(a2 << 7), -192.0);
+        LOLUNIT_ASSERT_EQUAL((double)(a2 << -7), -0.01171875);
+
+        LOLUNIT_ASSERT_EQUAL((double)(a3 >> 7), 0.0);
+        LOLUNIT_ASSERT_EQUAL((double)(a3 >> -7), 0.0);
+        LOLUNIT_ASSERT_EQUAL((double)(a3 << 7), 0.0);
+        LOLUNIT_ASSERT_EQUAL((double)(a3 << -7), 0.0);
+    }
 };
 
 } /* namespace lol */