Merge pull request #5 from Ninds/DenormalBoundaryInParse

FIX of Denormal boundary in parse #4
Ninds · Jul 1, 2020 · 7eea3b9 · 7eea3b9
2 parents 344bf9e + 5d98c2a
commit 7eea3b9
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Showing 2 changed files with 21 additions and 5 deletions.
diff --git a/Ryu.Net.UnitTests/Test_s2d_n_small.cs b/Ryu.Net.UnitTests/Test_s2d_n_small.cs
@@ -63,12 +63,25 @@ public void TestUTF16()
 
         }
 
+        // https://github.com/ulfjack/ryu/issues/173
+        [Fact]
+        public void TestDenormalBoundaryInParse()
+        {
+            double result = 0;
+            var testCase = "2.2250738585072013e-308";
+            double refValue = 2.2250738585072013e-308;
 
+            var st = RyuDotNet.Internal.Ryu.s2d_n(testCase, out result);
 
+            Assert.Equal(Status.SUCCESS, st);
+            Assert.Equal(refValue, result);
 
+        }
 
 
-    }
+
+
+        }
 
     public class SmallDataGenerator : IEnumerable<object[]>
     { 

diff --git a/Ryu.Net/Internal/s2d.cs b/Ryu.Net/Internal/s2d.cs
@@ -202,13 +202,16 @@ internal static Status s2d_n(ReadOnlySpan<byte> buffer, out double result)
             bool roundUp = (lastRemovedBit != 0) && (!trailingZeros || (((m2 >> shift) & 1) != 0));
 
 
-            uint64_t ieee_m2 = (m2 >> shift) + (roundUp ? 1U : 0);
-            if (ieee_m2 == (1ul << (DOUBLE_MANTISSA_BITS + 1)))
-            {
+            uint64_t ieee_m2 = (m2 >> shift) + (roundUp ? 1U : 0);
+            assert(ieee_m2 <= (1ul << (DOUBLE_MANTISSA_BITS + 1)));
+            ieee_m2 &= (1ul << DOUBLE_MANTISSA_BITS) -1;
+            if (ieee_m2 == 0 && roundUp)
+            {
+
                 // Due to how the IEEE represents +/-Infinity, we don't need to check for overflow here.
                 ieee_e2++;
             }
-            ieee_m2 &= (1ul << DOUBLE_MANTISSA_BITS) - 1;
+
             uint64_t ieee2 = (((((uint64_t)(signedM ? 1 : 0)) << DOUBLE_EXPONENT_BITS) | (uint64_t)ieee_e2) << DOUBLE_MANTISSA_BITS) | ieee_m2;
             result = int64Bits2Double(ieee2);
             return SUCCESS;