#67: edge case correction

Author: vpiotr

include/decimal.h

@@ -281,7 +281,30 @@ class dec_utils {
 public:
     // result = (value1 * value2) / divisor
     inline static int64 multDiv(const int64 value1, const int64 value2,
-            int64 divisor) {
+                                int64 divisor) {
+
+        if (value1 == 0 || value2 == 0) {
+            return 0;
+        }
+
+        if (divisor == 1) {
+            return value1 * value2;
+        }
+
+        if (value1 == 1) {
+            int64 result;
+            if (RoundPolicy::div_rounded(result, value2, divisor)) {
+                return result;
+            }
+        }
+
+        if (value2 == 1) {
+            int64 result;
+            if (RoundPolicy::div_rounded(result, value1, divisor)) {
+                return result;
+            }
+        }
+
         // we don't check for division by zero, the caller should - the next line will throw.
         const int64 value1int = value1 / divisor;
         int64 value1dec = value1 % divisor;

tests/decimalTest.cpp

@@ -36,6 +36,24 @@ BOOST_AUTO_TEST_CASE(decimalAsInteger)
     BOOST_CHECK_EQUAL(c.getAsInteger(), expectedValue);
 }
 
+BOOST_AUTO_TEST_CASE(issue67)
+{
+    using namespace std;
+    dec::decimal<4, dec::half_even_round_policy> p1("350.68");
+    dec::decimal<4, dec::half_even_round_policy> p2("359.2050");
+
+    dec::decimal<0, dec::half_even_round_policy> s1("550");
+    dec::decimal<0, dec::half_even_round_policy> s2("550");
+
+    dec::decimal<0, dec::half_even_round_policy> s_sum = s1 + s2;
+    dec::decimal<4, dec::half_even_round_policy> p_sum = p1 + p2;
+    dec::decimal<4, dec::half_even_round_policy> result = (p_sum / s_sum);
+
+    dec::decimal<4, dec::half_even_round_policy> expected("0.6454");
+
+    BOOST_CHECK_EQUAL(expected, result);
+}
+
 // test with values internally > 2^32
 BOOST_AUTO_TEST_CASE(decimalMidOverflow)
 {