Return 0 if binary exponent is too small

1 files changed, 11 insertions, 8 deletions

diff --git a/include/rapidjson/internal/diyfp.h b/include/rapidjson/internal/diyfp.h
index b02e0ca9..85243aff 100644
--- a/include/rapidjson/internal/diyfp.h
+++ b/include/rapidjson/internal/diyfp.h
@@ -1,5 +1,5 @@
 // Tencent is pleased to support the open source community by making RapidJSON available.
-// 
+//
 // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
 //
 // Licensed under the MIT License (the "License"); you may not use this file except
@@ -7,9 +7,9 @@
 //
 // http://opensource.org/licenses/MIT
 //
-// Unless required by applicable law or agreed to in writing, software distributed 
-// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
-// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
 // specific language governing permissions and limitations under the License.
 
 // This is a C++ header-only implementation of Grisu2 algorithm from the publication:
@@ -56,7 +56,7 @@ struct DiyFp {
         if (biased_e != 0) {
             f = significand + kDpHiddenBit;
             e = biased_e - kDpExponentBias;
-        } 
+        }
         else {
             f = significand;
             e = kDpMinExponent + 1;
@@ -142,9 +142,12 @@ struct DiyFp {
             uint64_t u64;
         }u;
         RAPIDJSON_ASSERT(f <= kDpHiddenBit + kDpSignificandMask);
-        RAPIDJSON_ASSERT(e >= kDpDenormalExponent);
+        if (e < kDpDenormalExponent) {
+            // Underflow.
+            return 0.0;
+        }
         RAPIDJSON_ASSERT(e < kDpMaxExponent);
-        const uint64_t be = (e == kDpDenormalExponent && (f & kDpHiddenBit) == 0) ? 0 : 
+        const uint64_t be = (e == kDpDenormalExponent && (f & kDpHiddenBit) == 0) ? 0 :
             static_cast<uint64_t>(e + kDpExponentBias);
         u.u64 = (f & kDpSignificandMask) | (be << kDpSignificandSize);
         return u.d;
@@ -226,7 +229,7 @@ inline DiyFp GetCachedPowerByIndex(size_t index) {
     RAPIDJSON_ASSERT(index < 87);
     return DiyFp(kCachedPowers_F[index], kCachedPowers_E[index]);
 }
-    
+
 inline DiyFp GetCachedPower(int e, int* K) {
 
     //int k = static_cast<int>(ceil((-61 - e) * 0.30102999566398114)) + 374;