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using System.IO;
namespace Ryujinx.Graphics.VDec
{
class H264BitStreamWriter : BitStreamWriter
{
public H264BitStreamWriter(Stream baseStream) : base(baseStream) { }
public void WriteU(int value, int valueSize)
{
WriteBits(value, valueSize);
}
public void WriteSe(int value)
{
WriteExpGolombCodedInt(value);
}
public void WriteUe(int value)
{
WriteExpGolombCodedUInt((uint)value);
}
public void End()
{
WriteBit(true);
Flush();
}
private void WriteExpGolombCodedInt(int value)
{
int sign = value <= 0 ? 0 : 1;
if (value < 0)
{
value = -value;
}
value = (value << 1) - sign;
WriteExpGolombCodedUInt((uint)value);
}
private void WriteExpGolombCodedUInt(uint value)
{
int size = 32 - CountLeadingZeros((int)value + 1);
WriteBits(1, size);
value -= (1u << (size - 1)) - 1;
WriteBits((int)value, size - 1);
}
private static readonly byte[] ClzNibbleTbl = { 4, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0 };
private static int CountLeadingZeros(int value)
{
if (value == 0)
{
return 32;
}
int nibbleIdx = 32;
int preCount, count = 0;
do
{
nibbleIdx -= 4;
preCount = ClzNibbleTbl[(value >> nibbleIdx) & 0b1111];
count += preCount;
}
while (preCount == 4);
return count;
}
}
}
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