Add span-based methods to Decimal (#32155)

* Add span-based methods to Decimal

* Address PR feedback

Add missing tests

* Address PR feedback

src/libraries/System.Data.Common/src/System/Data/SQLTypes/SQLDecimal.cs

@@ -486,7 +486,8 @@ public SqlDecimal(decimal value)
  // m_data1 = *pInt++; // lo part
  // m_data2 = *pInt++; // mid part
 
- int[] bits = decimal.GetBits(value);
+ Span<int> bits = stackalloc int[4];
+ decimal.GetBits(value, bits);
  uint sgnscl;
 
  unchecked

src/libraries/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/ILGen.cs

@@ -1079,7 +1079,9 @@ internal static void EmitArray(this ILGenerator il, Type arrayType)
 
  private static void EmitDecimal(this ILGenerator il, decimal value)
  {
- int[] bits = decimal.GetBits(value);
+ Span<int> bits = stackalloc int[4];
+ decimal.GetBits(value, bits);
+
  int scale = (bits[3] & int.MaxValue) >> 16;
  if (scale == 0)
  {

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

@@ -263,7 +263,7 @@
  <value>Combination of arguments to the DateTime constructor is out of the legal range.</value>
  </data>
  <data name="Arg_DecBitCtor" xml:space="preserve">
- <value>Decimal byte array constructor requires an array of length four containing valid decimal bytes.</value>
+ <value>Decimal constructor requires an array or span of four valid decimal bytes.</value>
  </data>
  <data name="Arg_DirectoryNotFoundException" xml:space="preserve">
  <value>Attempted to access a path that is not on the disk.</value>

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

@@ -243,10 +243,18 @@ public static long ToOACurrency(decimal value)
  // The possible binary representations of a particular value are all
  // equally valid, and all are numerically equivalent.
  //
- public Decimal(int[] bits)
+ public Decimal(int[] bits) :
+ this((ReadOnlySpan<int>)(bits ?? throw new ArgumentNullException(nameof(bits))))
+ {
+ }
+
+ /// <summary>
+ /// Initializes a new instance of <see cref="decimal"/> to a decimal value represented in binary and contained in the specified span.
+ /// </summary>
+ /// <param name="bits">A span of four <see cref="int"/>s containing a binary representation of a decimal value.</param>
+ /// <exception cref="ArgumentException">The length of <paramref name="bits"/> is not 4, or the representation of the decimal value in <paramref name="bits"/> is not valid.</exception>
+ public Decimal(ReadOnlySpan<int> bits)
  {
- if (bits == null)
- throw new ArgumentNullException(nameof(bits));
  if (bits.Length == 4)
  {
  int f = bits[3];
@@ -522,6 +530,50 @@ public static int[] GetBits(decimal d)
  return new int[] { d.lo, d.mid, d.hi, d.flags };
  }
 
+ /// <summary>
+ /// Converts the value of a specified instance of <see cref="decimal"/> to its equivalent binary representation.
+ /// </summary>
+ /// <param name="d">The value to convert.</param>
+ /// <param name="destination">The span into which to store the four-integer binary representation.</param>
+ /// <returns>Four, the number of integers in the binary representation.</returns>
+ /// <exception cref="ArgumentException">The destination span was not long enough to store the binary representation.</exception>
+ public static int GetBits(decimal d, Span<int> destination)
+ {
+ if ((uint)destination.Length <= 3)
+ {
+ ThrowHelper.ThrowArgumentException_DestinationTooShort();
+ }
+
+ destination[0] = d.lo;
+ destination[1] = d.mid;
+ destination[2] = d.hi;
+ destination[3] = d.flags;
+ return 4;
+ }
+
+ /// <summary>
+ /// Tries to convert the value of a specified instance of <see cref="decimal"/> to its equivalent binary representation.
+ /// </summary>
+ /// <param name="d">The value to convert.</param>
+ /// <param name="destination">The span into which to store the binary representation.</param>
+ /// <param name="valuesWritten">The number of integers written to the destination.</param>
+ /// <returns>true if the decimal's binary representation was written to the destination; false if the destination wasn't long enough.</returns>
+ public static bool TryGetBits(decimal d, Span<int> destination, out int valuesWritten)
+ {
+ if ((uint)destination.Length <= 3)
+ {
+ valuesWritten = 0;
+ return false;
+ }
+
+ destination[0] = d.lo;
+ destination[1] = d.mid;
+ destination[2] = d.hi;
+ destination[3] = d.flags;
+ valuesWritten = 4;
+ return true;
+ }
+
  internal static void GetBytes(in decimal d, byte[] buffer)
  {
  Debug.Assert(buffer != null && buffer.Length >= 16, "[GetBytes]buffer != null && buffer.Length >= 16");

src/libraries/System.Reflection.Metadata/src/System/Reflection/Internal/Utilities/DecimalUtilities.cs

@@ -8,12 +8,23 @@ internal static class DecimalUtilities
  {
  public static int GetScale(this decimal value)
  {
+#if NETCOREAPP
+ Span<int> bits = stackalloc int[4];
+ decimal.GetBits(value, bits);
+ return unchecked((byte)(bits[3] >> 16));
+#else
  return unchecked((byte)(decimal.GetBits(value)[3] >> 16));
+#endif
  }
 
  public static void GetBits(this decimal value, out bool isNegative, out byte scale, out uint low, out uint mid, out uint high)
  {
+#if NETCOREAPP
+ Span<int> bits = stackalloc int[4];
+ decimal.GetBits(value, bits);
+#else
  int[] bits = decimal.GetBits(value);
+#endif
 
  // The return value is a four-element array of 32-bit signed integers.
  // The first, second, and third elements of the returned array contain the low, middle, and high 32 bits of the 96-bit integer number.

src/libraries/System.Runtime.Numerics/src/System/Numerics/BigInteger.cs

@@ -206,7 +206,8 @@ public BigInteger(double value)
  public BigInteger(decimal value)
  {
  // First truncate to get scale to 0 and extract bits
- int[] bits = decimal.GetBits(decimal.Truncate(value));
+ Span<int> bits = stackalloc int[4];
+ decimal.GetBits(decimal.Truncate(value), bits);
 
  Debug.Assert(bits.Length == 4 && (bits[3] & DecimalScaleFactorMask) == 0);
 

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -883,6 +883,7 @@ public void GetObjectData(System.Runtime.Serialization.SerializationInfo info, S
  public Decimal(int value) { throw null; }
  public Decimal(int lo, int mid, int hi, bool isNegative, byte scale) { throw null; }
  public Decimal(int[] bits) { throw null; }
+ public Decimal(System.ReadOnlySpan<int> bits) { throw null; }
  public Decimal(long value) { throw null; }
  public Decimal(float value) { throw null; }
  [System.CLSCompliantAttribute(false)]
@@ -901,6 +902,7 @@ public void GetObjectData(System.Runtime.Serialization.SerializationInfo info, S
  public static System.Decimal Floor(System.Decimal d) { throw null; }
  public static System.Decimal FromOACurrency(long cy) { throw null; }
  public static int[] GetBits(System.Decimal d) { throw null; }
+ public static int GetBits(System.Decimal d, System.Span<int> destination) { throw null; }
  public override int GetHashCode() { throw null; }
  public System.TypeCode GetTypeCode() { throw null; }
  public static System.Decimal Multiply(System.Decimal d1, System.Decimal d2) { throw null; }
@@ -998,6 +1000,7 @@ void System.Runtime.Serialization.IDeserializationCallback.OnDeserialization(obj
  public static ulong ToUInt64(System.Decimal d) { throw null; }
  public static System.Decimal Truncate(System.Decimal d) { throw null; }
  public bool TryFormat(System.Span<char> destination, out int charsWritten, System.ReadOnlySpan<char> format = default(System.ReadOnlySpan<char>), System.IFormatProvider? provider = null) { throw null; }
+ public static bool TryGetBits(System.Decimal d, System.Span<int> destination, out int valuesWritten) { throw null; }
  public static bool TryParse(System.ReadOnlySpan<char> s, out System.Decimal result) { throw null; }
  public static bool TryParse(System.ReadOnlySpan<char> s, System.Globalization.NumberStyles style, System.IFormatProvider? provider, out System.Decimal result) { throw null; }
  public static bool TryParse(string? s, out System.Decimal result) { throw null; }

src/libraries/System.Runtime/tests/System/DecimalTests.cs

@@ -140,6 +140,13 @@ public void Ctor_IntArray(int[] value, decimal expected)
  Assert.Equal(expected, new decimal(value));
  }
 
+ [Theory]
+ [MemberData(nameof(Ctor_IntArray_TestData))]
+ public void Ctor_IntSpan(int[] value, decimal expected)
+ {
+ Assert.Equal(expected, new decimal(value.AsSpan()));
+ }
+
  [Fact]
  public void Ctor_NullBits_ThrowsArgumentNullException()
  {
@@ -155,6 +162,7 @@ public void Ctor_NullBits_ThrowsArgumentNullException()
  public void Ctor_InvalidBits_ThrowsArgumentException(int[] bits)
  {
  AssertExtensions.Throws<ArgumentException>(null, () => new decimal(bits));
+ AssertExtensions.Throws<ArgumentException>(null, () => new decimal(bits.AsSpan()));
  }
 
  [Theory]
@@ -619,6 +627,54 @@ public static void GetBits(decimal input, int[] expected)
  Assert.Equal(input, newValue);
  }
 
+ [Theory]
+ [MemberData(nameof(GetBits_TestData))]
+ public static void GetBitsSpan(decimal input, int[] expected)
+ {
+ Span<int> bits = new int[4];
+ int bitsWritten = decimal.GetBits(input, bits);
+
+ Assert.Equal(4, bitsWritten);
+ Assert.Equal(expected, bits.ToArray());
+
+ bool sign = (bits[3] & 0x80000000) != 0;
+ byte scale = (byte)((bits[3] >> 16) & 0x7F);
+ decimal newValue = new decimal(bits[0], bits[1], bits[2], sign, scale);
+
+ Assert.Equal(input, newValue);
+ }
+
+ [Fact]
+ public static void GetBitsSpan_TooShort_ThrowsArgumentException()
+ {
+ AssertExtensions.Throws<ArgumentException>("destination", () => decimal.GetBits(123, new int[3]));
+ }
+
+ [Theory]
+ [MemberData(nameof(GetBits_TestData))]
+ public static void TryGetBits(decimal input, int[] expected)
+ {
+ Span<int> bits;
+ int valuesWritten;
+
+ bits = new int[3] { 42, 43, 44 };
+ Assert.False(decimal.TryGetBits(input, bits, out valuesWritten));
+ Assert.Equal(0, valuesWritten);
+ Assert.Equal(new int[3] { 42, 43, 44 }, bits.ToArray());
+
+ bits = new int[4];
+ Assert.True(decimal.TryGetBits(input, bits, out valuesWritten));
+ Assert.Equal(4, valuesWritten);
+ Assert.Equal(expected, bits.ToArray());
+
+ bits = new int[5];
+ bits[4] = 42;
+ Assert.True(decimal.TryGetBits(input, bits, out valuesWritten));
+ Assert.Equal(4, valuesWritten);
+ Assert.Equal(expected, bits.Slice(0, 4).ToArray());
+ Assert.Equal(42, bits[4]);
+ }
+
  [Fact]
  public void GetTypeCode_Invoke_ReturnsDecimal()
  {