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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Diagnostics;
using System.Text;
using Internal.Runtime.CompilerServices;
namespace System
{
internal static partial class Number
{
// We need 1 additional byte, per length, for the terminating null
internal const int DecimalNumberBufferLength = 29 + 1 + 1; // 29 for the longest input + 1 for rounding
internal const int DoubleNumberBufferLength = 767 + 1 + 1; // 767 for the longest input + 1 for rounding: 4.9406564584124654E-324
internal const int Int32NumberBufferLength = 10 + 1; // 10 for the longest input: 2,147,483,647
internal const int Int64NumberBufferLength = 19 + 1; // 19 for the longest input: 9,223,372,036,854,775,807
internal const int SingleNumberBufferLength = 112 + 1 + 1; // 112 for the longest input + 1 for rounding: 1.40129846E-45
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 unsafe ref struct NumberBuffer
{
public int DigitsCount;
public int Scale;
public bool IsNegative;
public bool HasNonZeroTail;
public NumberBufferKind Kind;
public Span<byte> Digits;
public NumberBuffer(NumberBufferKind kind, byte* digits, int digitsLength)
{
Debug.Assert(digits != null);
Debug.Assert(digitsLength > 0);
DigitsCount = 0;
Scale = 0;
IsNegative = false;
HasNonZeroTail = false;
Kind = kind;
Digits = new Span<byte>(digits, digitsLength);
#if DEBUG
Digits.Fill(0xCC);
#endif
Digits[0] = (byte)('\0');
CheckConsistency();
}
[Conditional("DEBUG")]
public void CheckConsistency()
{
#if DEBUG
Debug.Assert((Kind == NumberBufferKind.Integer) || (Kind == NumberBufferKind.Decimal) || (Kind == NumberBufferKind.FloatingPoint));
Debug.Assert(Digits[0] != '0', "Leading zeros should never be stored in a Number");
int numDigits;
for (numDigits = 0; numDigits < Digits.Length; numDigits++)
{
byte digit = Digits[numDigits];
if (digit == 0)
{
break;
}
Debug.Assert((digit >= '0') && (digit <= '9'), "Unexpected character found in Number");
}
Debug.Assert(numDigits == DigitsCount, "Null terminator found in unexpected location in Number");
Debug.Assert(numDigits < Digits.Length, "Null terminator not found in Number");
#endif // DEBUG
}
public byte* GetDigitsPointer()
{
// This is safe to do since we are a ref struct
return (byte*)(Unsafe.AsPointer(ref Digits[0]));
}
//
// Code coverage note: This only exists so that Number displays nicely in the VS watch window. So yes, I know it works.
//
public override string ToString()
{
StringBuilder sb = new StringBuilder();
sb.Append('[');
sb.Append('"');
for (int i = 0; i < Digits.Length; i++)
{
byte digit = Digits[i];
if (digit == 0)
{
break;
}
sb.Append((char)(digit));
}
sb.Append('"');
sb.Append(", Length = " + DigitsCount);
sb.Append(", Scale = " + Scale);
sb.Append(", IsNegative = " + IsNegative);
sb.Append(", HasNonZeroTail = " + HasNonZeroTail);
sb.Append(", Kind = " + Kind);
sb.Append(']');
return sb.ToString();
}
}
internal enum NumberBufferKind : byte
{
Unknown = 0,
Integer = 1,
Decimal = 2,
FloatingPoint = 3,
}
}
}
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