using System;
using System.Runtime.InteropServices;
namespace Vanara.Extensions
{
/// Static methods to help with bit manipulation.
/// This class is intended to support whole numbers. Without a specific constraint for numbers, the list of constraints helps to limit incorrect types, but is NOT foolproof.
public static class BitHelper
{
/// Gets the bit value at the specified index in a bit vector.
/// The type of the bit vector. Must be of type .
/// The bit vector.
/// The zero-based index of the bit to get.
/// if the bit is set (1); otherwise.
public static bool GetBit(T bits, byte idx) where T : struct, IComparable, IComparable, IConvertible, IEquatable, IFormattable =>
(idx < (Marshal.SizeOf(typeof(T)) * 8)) ? (bits.ToInt64(null) & 1 << idx) != 0 : throw new ArgumentOutOfRangeException(nameof(idx));
/// Gets the bit array value from the specified range in a bit vector.
/// The type of the bit vector. Must be of type .
/// The bit vector.
/// The zero-based start index of the bit range to get.
/// The number of sequential bits to fetch starting at .
/// The value of the requested bit range.
public static T GetBits(T bits, byte startIdx, byte count) where T : struct, IComparable, IComparable, IConvertible, IEquatable, IFormattable
{
if (startIdx >= (Marshal.SizeOf(typeof(T)) * 8)) throw new ArgumentOutOfRangeException(nameof(startIdx));
if (count + startIdx > (Marshal.SizeOf(typeof(T)) * 8)) throw new ArgumentOutOfRangeException(nameof(count));
return (T)Convert.ChangeType((bits.ToInt64(null) >> startIdx) & ((1 << count) - 1), typeof(T));
}
/// Sets the bit value at the specified index in a bit vector.
/// The type of the bit vector. Must be of type .
/// The bit vector.
/// The index of the bit to set.
/// If set to , set the bit (= 1); otherwise, clear the bit (= 0).
public static void SetBit(ref T bits, byte idx, bool value) where T : struct, IComparable, IComparable, IConvertible, IEquatable, IFormattable
{
if (idx >= (Marshal.SizeOf(typeof(T)) * 8)) throw new ArgumentOutOfRangeException(nameof(idx));
long bit = 1 << idx;
var l = bits.ToInt64(null);
bits = (T)Convert.ChangeType(value ? l | bit : l & ~bit, typeof(T));
}
/// Sets the bit values at the specified range in a bit vector.
/// The type of the bit vector. Must be of type .
/// The type of the value. Must be of type .
/// The bit vector.
/// The zero-based start index of the bit range to set.
/// The number of sequential bits to set starting at .
/// The value to set within the specified range of .
public static void SetBits(ref T bits, byte startIdx, byte count, TValue value) where T : struct, IComparable, IComparable, IConvertible, IEquatable, IFormattable where TValue : struct, IComparable, IComparable, IConvertible, IEquatable, IFormattable
{
if (startIdx >= (Marshal.SizeOf(typeof(T)) * 8)) throw new ArgumentOutOfRangeException(nameof(startIdx));
if (count + startIdx > (Marshal.SizeOf(typeof(T)) * 8)) throw new ArgumentOutOfRangeException(nameof(count));
var val = value.ToInt64(null);
if (val >= (1 << count)) throw new ArgumentOutOfRangeException(nameof(value));
bits = (T)Convert.ChangeType(bits.ToInt64(null) & ~(((1 << count) - 1) << startIdx) | (val << startIdx), typeof(T));
}
}
}