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Use generic math in Util.BitUtil

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Alex Barney 2022-12-13 18:09:00 -07:00
parent 4108a6c149
commit 7fce26e899
2 changed files with 98 additions and 30 deletions
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41
src/LibHac/Util/BitUtil.cs
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@ -5,47 +5,28 @@ namespace LibHac.Util;
public static class BitUtil public static class BitUtil
{ {
public static bool IsPowerOfTwo(int value)
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsPowerOfTwo<T>(T value) where T : IBitwiseOperators<T, T, T>, INumberBase<T>
{ {
return value > 0 && ResetLeastSignificantOneBit(value) == 0; return !T.IsNegative(value) && !T.IsZero(value) && T.IsZero(ResetLeastSignificantOneBit(value));
} }
[MethodImpl(MethodImplOptions.AggressiveInlining)] [MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsPowerOfTwo(long value) public static T ResetLeastSignificantOneBit<T>(T value) where T : IBitwiseOperators<T, T, T>, INumberBase<T>
{ {
return value > 0 && ResetLeastSignificantOneBit(value) == 0; return value & unchecked(value - T.One);
} }
[MethodImpl(MethodImplOptions.AggressiveInlining)] [MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsPowerOfTwo(ulong value) public static int CountLeadingZeros<T>(T value) where T : IBinaryInteger<T>
{ {
return value > 0 && ResetLeastSignificantOneBit(value) == 0; return int.CreateTruncating(T.LeadingZeroCount(value));
} }
private static int ResetLeastSignificantOneBit(int value) [MethodImpl(MethodImplOptions.AggressiveInlining)]
public static T DivideUp<T>(T value, T divisor) where T : INumberBase<T>
{ {
return value & (value - 1); return unchecked(value + divisor - T.One) / divisor;
} }
private static long ResetLeastSignificantOneBit(long value)
{
return value & (value - 1);
}
private static ulong ResetLeastSignificantOneBit(ulong value)
{
return value & (value - 1);
}
public static int CountLeadingZeros(uint value)
{
return BitOperations.LeadingZeroCount(value);
}
// DivideUp comes from a C++ template that always casts to unsigned types
public static uint DivideUp(uint value, uint divisor) => (value + divisor - 1) / divisor;
public static ulong DivideUp(ulong value, ulong divisor) => (value + divisor - 1) / divisor;
public static int DivideUp(int value, int divisor) => (int)DivideUp((uint)value, (uint)divisor);
public static long DivideUp(long value, long divisor) => (long)DivideUp((ulong)value, (ulong)divisor);
} }

87
tests/LibHac.Tests/Util/BitUtilTests.cs Normal file
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@ -0,0 +1,87 @@
using LibHac.Util;
using Xunit;
namespace LibHac.Tests.Util;
public class BitUtilTests
{
[Theory]
[InlineData(0x80, 0)]
[InlineData(0x00, 8)]
public void CountLeadingZeros_Byte(byte value, int expectedValue)
{
Assert.Equal(expectedValue, BitUtil.CountLeadingZeros(value));
}
[Theory]
[InlineData(0x0080, 8)]
[InlineData(0x0000, 16)]
public void CountLeadingZeros_Short(short value, int expectedValue)
{
Assert.Equal(expectedValue, BitUtil.CountLeadingZeros(value));
}
[Theory]
[InlineData(0b0000_1000_0110_0000, 0b0000_1000_0100_0000)]
[InlineData(0b0000_1000_0110_1111, 0b0000_1000_0110_1110)]
[InlineData(unchecked((short)0b1000_0000_0000_0000), 0b0000_0000_0000_0000)]
[InlineData(0, 0)]
public void ResetLeastSignificantOneBit_Short(short value, short expectedValue)
{
Assert.Equal(expectedValue, BitUtil.ResetLeastSignificantOneBit(value));
}
[Theory]
[InlineData(0b0101_0000_0000_0000_0000, 0b0100_0000_0000_0000_0000)]
[InlineData(0b1111_0000_1000_0110_1111, 0b1111_0000_1000_0110_1110)]
[InlineData(0b0100_1000_0000_0000_0000, 0b0100_0000_0000_0000_0000)]
[InlineData(0, 0)]
public void ResetLeastSignificantOneBit_Uint(uint value, uint expectedValue)
{
Assert.Equal(expectedValue, BitUtil.ResetLeastSignificantOneBit(value));
}
[Theory]
[InlineData(0x80, true)]
[InlineData(0x81, false)]
[InlineData(0, false)]
[InlineData(short.MinValue, false)]
public void IsPowerOfTwo_Short(short value, bool expectedValue)
{
Assert.Equal(expectedValue, BitUtil.IsPowerOfTwo(value));
}
[Theory]
[InlineData(0x0000100000000000, true)]
[InlineData(0x0000100000004000, false)]
[InlineData(0, false)]
public void IsPowerOfTwo_Ulong(ulong value, bool expectedValue)
{
Assert.Equal(expectedValue, BitUtil.IsPowerOfTwo(value));
}
[Theory]
[InlineData(-55, -2, 29)]
[InlineData(-55, 2, -27)]
[InlineData(0, 26, 0)]
[InlineData(-55, -26, 3)]
[InlineData(55, -26, -1)]
[InlineData(int.MinValue, -26, -82595523)]
public void DivideUp_Int(int value, int divisor, int expectedValue)
{
Assert.Equal(expectedValue, BitUtil.DivideUp(value, divisor));
}
[Theory]
[InlineData(55, 2, 28)]
[InlineData(0, 26, 0)]
[InlineData(1127, 24, 47)]
[InlineData(1128, 24, 47)]
[InlineData(1129, 24, 48)]
[InlineData(567, 987, 1)]
[InlineData(int.MaxValue, 26, 82595525)]
public void DivideUp_Uint(uint value, uint divisor, uint expectedValue)
{
Assert.Equal(expectedValue, BitUtil.DivideUp(value, divisor));
}
}