Add Decimal32, Decimal64, Decimal128

src/libraries/Common/src/System/Number.NumberBuffer.cs

@@ -21,6 +21,9 @@ internal static partial class Number
         internal const int UInt32NumberBufferLength = 10 + 1;   // 10 for the longest input: 4,294,967,295
         internal const int UInt64NumberBufferLength = 20 + 1;   // 20 for the longest input: 18,446,744,073,709,551,615
         internal const int UInt128NumberBufferLength = 39 + 1; // 39 for the longest input: 340,282,366,920,938,463,463,374,607,431,768,211,455
+        internal const int Decimal32NumberBufferLength = 97 + 1 + 1; // 97 for the longest input + 1 for rounding
+        internal const int Decimal64NumberBufferLength = 385 + 1 + 1; // 385 for the longest input + 1 for rounding
+        internal const int Decimal128NumberBufferLength = 6145 + 1 + 1; // 6145 for the longest input + 1 for rounding
 
         internal unsafe ref struct NumberBuffer
         {

src/libraries/System.Private.CoreLib/src/Resources/Strings.resx

@@ -537,6 +537,15 @@
   <data name="Arg_MustBeDecimal" xml:space="preserve">
     <value>Object must be of type Decimal.</value>
   </data>
+  <data name="Arg_MustBeDecimal32" xml:space="preserve">
+    <value>Object must be of type Decimal32.</value>
+  </data>
+  <data name="Arg_MustBeDecimal64" xml:space="preserve">
+    <value>Object must be of type Decimal64.</value>
+  </data>
+  <data name="Arg_MustBeDecimal128" xml:space="preserve">
+    <value>Object must be of type Decimal128.</value>
+  </data>
   <data name="Arg_MustBeDelegate" xml:space="preserve">
     <value>Type must derive from Delegate.</value>
   </data>

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -430,6 +430,10 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\IFormatProvider.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IFormattable.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Index.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Number.DecimalIeee754.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Numerics\Decimal128.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Numerics\Decimal32.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Numerics\Decimal64.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\Any1CharPackedSearchValues.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\Any1CharPackedIgnoreCaseSearchValues.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\Any2CharPackedIgnoreCaseSearchValues.cs" />

src/libraries/System.Private.CoreLib/src/System/Number.BigInteger.cs

@@ -1324,6 +1324,31 @@ public ulong ToUInt64()
                 return 0;
             }
 
+            public UInt128 ToUInt128()
+            {
+                if (_length > 3)
+                {
+                    return new UInt128(((ulong)(_blocks[3]) << 96) + ((ulong)_blocks[2] << 64), ((ulong)(_blocks[1]) << 32) + _blocks[0]);
+                }
+
+                if (_length > 2)
+                {
+                    return new UInt128(((ulong)_blocks[2] << 64), ((ulong)(_blocks[1]) << 32) + _blocks[0]);
+                }
+
+                if (_length > 1)
+                {
+                    return ((ulong)(_blocks[1]) << 32) + _blocks[0];
+                }
+
+                if (_length > 0)
+                {
+                    return _blocks[0];
+                }
+
+                return 0;
+            }
+
             private void Clear(uint length) =>
                 NativeMemory.Clear(
                     (byte*)Unsafe.AsPointer(ref _blocks[0]), // This is safe to do since we are a ref struct