revert csharp NaN

microsoft · Sep 24, 2024 · 4664ddc · 4664ddc
1 parent 718e05b
commit 4664ddc
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Showing 2 changed files with 4 additions and 2 deletions.
diff --git a/csharp/src/Microsoft.ML.OnnxRuntime/OrtFloat16.shared.cs b/csharp/src/Microsoft.ML.OnnxRuntime/OrtFloat16.shared.cs
@@ -259,7 +259,7 @@ internal static float CreateSingle(bool sign, byte exponent, uint significand)
         /// <summary>
         /// Float16 NaN
         /// </summary>
-        public static Float16 NaN => new Float16(PositiveQNaNBits);                       //  quiet NaN
+        public static Float16 NaN => new Float16(NegativeQNaNBits);                       // Same as System.Half.NaN
 
         /// <summary>
         /// Float16 Zero value
@@ -903,7 +903,7 @@ private static ushort RoundPackToFloat16(bool sign, short exp, ushort sig)
         /// <summary>
         /// BFloat16 NaN
         /// </summary>
-        public static BFloat16 NaN => new BFloat16(PositiveQNaNBits); // quiet NaN
+        public static BFloat16 NaN => new BFloat16(NegativeQNaNBits); // .Net has no BFloat16. Follow Float16 style.
 
         /// <summary>
         /// BFloat16 Positive Zero

diff --git a/include/onnxruntime/core/framework/float16.h b/include/onnxruntime/core/framework/float16.h
@@ -318,6 +318,8 @@ class numeric_limits<onnxruntime::MLFloat16> {
   }
 
   static constexpr onnxruntime::MLFloat16 quiet_NaN() noexcept {
+    // The most significant fraction bit shall be 1, and no limitation on other fraction bits.
+    // Note that most frameworks use 0x7E00; while CUDA uses 0x7FFF; .Net System.Half.NaN uses 0xFE00;
     return onnxruntime::MLFloat16::FromBits(0x7E00U);  // Bits: sign(0), exponent(111,11), fraction(10,0000,0000)
   }