/// <summary>
/// Reads the specified number of bits, clamped between one and <paramref name="maxBitCount"/>, into the given buffer.
/// </summary>
/// <param name="destination">The destination span.</param>
/// <param name="bitCount">The number of bits to read.</param>
/// <param name="maxBitCount">The maximum amount of bits to read.</param>
/// <exception cref="EndOfMessageException"></exception>
public static void ReadBits(this IBitBuffer buffer, Span <byte> destination, int bitCount, int maxBitCount)
{
Debug.Assert(bitCount >= 1);
Debug.Assert(bitCount <= maxBitCount);
buffer.ReadBits(destination, bitCount);
}
/// <summary>
/// Reads a <see cref="int"/> stored in 1 to 32 bits, written by <see cref="Write(int, int)"/>.
/// </summary>
/// <exception cref="EndOfMessageException"></exception>
public static int ReadInt32(this IBitBuffer buffer, int bitCount)
{
Span <byte> tmp = stackalloc byte[sizeof(int)];
if (bitCount == tmp.Length * 8)
{
buffer.Read(tmp);
return(BinaryPrimitives.ReadInt32LittleEndian(tmp));
}
tmp.Clear();
buffer.ReadBits(tmp, bitCount, tmp.Length * 8);
int value = BinaryPrimitives.ReadInt32LittleEndian(tmp);
int signBit = 1 << (bitCount - 1);
if ((value & signBit) == 0)
{
return(value); // positive
}
// negative
unchecked
{
uint mask = ((uint)-1) >> (33 - bitCount);
uint nValue = ((uint)value & mask) + 1;
return(-(int)nValue);
}
}
/// <summary>
/// Reads a <see cref="long"/> stored in 1 to 64 bits, written by <see cref="Write(long, int)"/>.
/// </summary>
/// <exception cref="EndOfMessageException"></exception>
public static long ReadInt64(this IBitBuffer buffer, int bitCount)
{
Span <byte> tmp = stackalloc byte[sizeof(long)];
if (bitCount == tmp.Length * 8)
{
buffer.Read(tmp);
return(BinaryPrimitives.ReadInt64LittleEndian(tmp));
}
tmp.Clear();
buffer.ReadBits(tmp, bitCount, tmp.Length * 8);
long value = BinaryPrimitives.ReadInt64LittleEndian(tmp);
long signBit = 1 << (bitCount - 1);
if ((value & signBit) == 0)
{
return(value); // positive
}
// negative
unchecked
{
ulong mask = ((ulong)-1) >> (65 - bitCount);
ulong nValue = ((ulong)value & mask) + 1;
return(-(long)nValue);
}
}
public static ulong ReadUInt64(this IBitBuffer buffer, int bitCount)
{
Span <byte> tmp = stackalloc byte[sizeof(ulong)];
tmp.Clear();
buffer.ReadBits(tmp, bitCount, tmp.Length * 8);
return(BinaryPrimitives.ReadUInt64LittleEndian(tmp));
}
/// <summary>
/// Reads bytes into the given span.
/// </summary>
/// <param name="destination">The destination span.</param>
public static int StreamRead(this IBitBuffer buffer, Span <byte> destination)
{
if (buffer.IsByteAligned())
{
int remainingBytes = Math.Min(buffer.ByteLength - buffer.BytePosition, destination.Length);
buffer.Read(destination.Slice(0, remainingBytes));
return(remainingBytes);
}
else
{
int remainingBits = Math.Min(buffer.BitLength - buffer.BitPosition, destination.Length * 8);
buffer.ReadBits(destination, remainingBits);
return(NetUtility.DivBy8(remainingBits));
}
}
