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added LsbBitStream class.

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This commit is contained in:
morkt 2015-10-19 09:03:32 +04:00
parent c396b86c22
commit 75a85ee85a
1 changed files with 67 additions and 28 deletions
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95
ArcFormats/BitStream.cs
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@ -29,48 +29,27 @@ using System.IO;
namespace GameRes.Formats namespace GameRes.Formats
{ {
public class MsbBitStream : IDisposable public class BitStream : IDisposable
{ {
Stream m_input; protected Stream m_input;
bool m_should_dispose; private bool m_should_dispose;
protected int m_bits = 0;
protected int m_cached_bits = 0;
public Stream Input { get { return m_input; } } public Stream Input { get { return m_input; } }
public MsbBitStream (Stream file, bool leave_open = false) protected BitStream (Stream file, bool leave_open)
{ {
m_input = file; m_input = file;
m_should_dispose = !leave_open; m_should_dispose = !leave_open;
} }
int m_bits = 0;
int m_cached_bits = 0;
public void Reset () public void Reset ()
{ {
m_cached_bits = 0; m_cached_bits = 0;
} }
public int GetNextBit ()
{
return GetBits (1);
}
public int GetBits (int count)
{
Debug.Assert (count <= 24, "MsbBitStream does not support sequences longer than 24 bits");
while (m_cached_bits < count)
{
int b = m_input.ReadByte();
if (-1 == b)
return -1;
m_bits = (m_bits << 8) | b;
m_cached_bits += 8;
}
int mask = (1 << count) - 1;
m_cached_bits -= count;
return (m_bits >> m_cached_bits) & mask;
}
#region IDisposable Members #region IDisposable Members
bool m_disposed = false; bool m_disposed = false;
@ -91,4 +70,64 @@ namespace GameRes.Formats
} }
#endregion #endregion
} }
public class MsbBitStream : BitStream
{
public MsbBitStream (Stream file, bool leave_open = false)
: base (file, leave_open)
{
}
public int GetBits (int count)
{
Debug.Assert (count <= 24, "MsbBitStream does not support sequences longer than 24 bits");
while (m_cached_bits < count)
{
int b = m_input.ReadByte();
if (-1 == b)
return -1;
m_bits = (m_bits << 8) | b;
m_cached_bits += 8;
}
int mask = (1 << count) - 1;
m_cached_bits -= count;
return (m_bits >> m_cached_bits) & mask;
}
public int GetNextBit ()
{
return GetBits (1);
}
}
public class LsbBitStream : BitStream
{
public LsbBitStream (Stream file, bool leave_open = false)
: base (file, leave_open)
{
}
public int GetBits (int count)
{
Debug.Assert (count <= 24, "LsbBitStream does not support sequences longer than 24 bits");
while (m_cached_bits < count)
{
int b = m_input.ReadByte();
if (-1 == b)
return -1;
m_bits |= b << m_cached_bits;
m_cached_bits += 8;
}
int mask = (1 << count) - 1;
int value = m_bits & mask;
m_bits = (int)((uint)m_bits >> count);
m_cached_bits -= count;
return value;
}
public int GetNextBit ()
{
return GetBits (1);
}
}
} }