Updating System.Runtime.InteropServices.NFloat to support generic math (

#68141)

* Updating NFloat to implement IBinaryFloatingPointIeee754 and IMinMaxValue

* Adding tests for the NFloat generic math support

* Fixing NFloat to expose the APIs for getting the exponent and significand

* Fix the NFloat.GetSignificandByteCount implementation

src/libraries/System.Runtime/tests/System/GenericMathHelpers.cs → src/libraries/Common/tests/System/GenericMathHelpers.cs

@@ -4,7 +4,7 @@
 using System.Globalization;
 using System.Numerics;
 
-namespace System.Tests
+namespace System
 {
     public static class AdditionOperatorsHelper<TSelf, TOther, TResult>
         where TSelf : IAdditionOperators<TSelf, TOther, TResult>

src/libraries/System.Private.CoreLib/src/System/Double.cs

@@ -48,19 +48,19 @@ public readonly struct Double
         public const double NaN = (double)0.0 / (double)0.0;
 
         /// <summary>Represents the additive identity (0).</summary>
-        private const double AdditiveIdentity = 0.0;
+        internal const double AdditiveIdentity = 0.0;
 
         /// <summary>Represents the multiplicative identity (1).</summary>
-        private const double MultiplicativeIdentity = 1.0;
+        internal const double MultiplicativeIdentity = 1.0;
 
         /// <summary>Represents the number one (1).</summary>
-        private const double One = 1.0;
+        internal const double One = 1.0;
 
         /// <summary>Represents the number zero (0).</summary>
-        private const double Zero = 0.0;
+        internal const double Zero = 0.0;
 
         /// <summary>Represents the number negative one (-1).</summary>
-        private const double NegativeOne = -1.0;
+        internal const double NegativeOne = -1.0;
 
         /// <summary>Represents the number negative zero (-0).</summary>
         public const double NegativeZero = -0.0;
@@ -105,7 +105,7 @@ public readonly struct Double
         internal const ulong MinTrailingSignificand = 0x0000_0000_0000_0000;
         internal const ulong MaxTrailingSignificand = 0x000F_FFFF_FFFF_FFFF;
 
-        private ushort BiasedExponent
+        internal ushort BiasedExponent
         {
             get
             {
@@ -114,23 +114,23 @@ private ushort BiasedExponent
             }
         }
 
-        private short Exponent
+        internal short Exponent
         {
             get
             {
                 return (short)(BiasedExponent - ExponentBias);
             }
         }
 
-        private ulong Significand
+        internal ulong Significand
         {
             get
             {
                 return TrailingSignificand | ((BiasedExponent != 0) ? (1UL << BiasedExponentShift) : 0UL);
             }
         }
 
-        private ulong TrailingSignificand
+        internal ulong TrailingSignificand
         {
             get
             {

src/libraries/System.Private.CoreLib/src/System/Half.cs

@@ -100,7 +100,7 @@ internal Half(ushort value)
 
         private Half(bool sign, ushort exp, ushort sig) => _value = (ushort)(((sign ? 1 : 0) << SignShift) + (exp << BiasedExponentShift) + sig);
 
-        private byte BiasedExponent
+        internal byte BiasedExponent
         {
             get
             {
@@ -109,23 +109,23 @@ private byte BiasedExponent
             }
         }
 
-        private sbyte Exponent
+        internal sbyte Exponent
         {
             get
             {
                 return (sbyte)(BiasedExponent - ExponentBias);
             }
         }
 
-        private ushort Significand
+        internal ushort Significand
         {
             get
             {
                 return (ushort)(TrailingSignificand | ((BiasedExponent != 0) ? (1U << BiasedExponentShift) : 0U));
             }
         }
 
-        private ushort TrailingSignificand
+        internal ushort TrailingSignificand
         {
             get
             {

src/libraries/System.Private.CoreLib/src/System/Single.cs

@@ -47,19 +47,19 @@ public readonly struct Single
         public const float NaN = (float)0.0 / (float)0.0;
 
         /// <summary>Represents the additive identity (0).</summary>
-        private const float AdditiveIdentity = 0.0f;
+        internal const float AdditiveIdentity = 0.0f;
 
         /// <summary>Represents the multiplicative identity (1).</summary>
-        private const float MultiplicativeIdentity = 1.0f;
+        internal const float MultiplicativeIdentity = 1.0f;
 
         /// <summary>Represents the number one (1).</summary>
-        private const float One = 1.0f;
+        internal const float One = 1.0f;
 
         /// <summary>Represents the number zero (0).</summary>
-        private const float Zero = 0.0f;
+        internal const float Zero = 0.0f;
 
         /// <summary>Represents the number negative one (-1).</summary>
-        private const float NegativeOne = -1.0f;
+        internal const float NegativeOne = -1.0f;
 
         /// <summary>Represents the number negative zero (-0).</summary>
         public const float NegativeZero = -0.0f;
@@ -104,7 +104,7 @@ public readonly struct Single
         internal const uint MinTrailingSignificand = 0x0000_0000;
         internal const uint MaxTrailingSignificand = 0x007F_FFFF;
 
-        private byte BiasedExponent
+        internal byte BiasedExponent
         {
             get
             {
@@ -113,23 +113,23 @@ private byte BiasedExponent
             }
         }
 
-        private sbyte Exponent
+        internal sbyte Exponent
         {
             get
             {
                 return (sbyte)(BiasedExponent - ExponentBias);
             }
         }
 
-        private uint Significand
+        internal uint Significand
         {
             get
             {
                 return TrailingSignificand | ((BiasedExponent != 0) ? (1U << BiasedExponentShift) : 0U);
             }
         }
 
-        private uint TrailingSignificand
+        internal uint TrailingSignificand
         {
             get
             {