mirror of
https://github.com/Ryujinx/Ryujinx.git
synced 2024-08-19 23:28:42 +02:00
121 lines
2.8 KiB
C#
121 lines
2.8 KiB
C#
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using System;
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using System.Numerics;
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namespace Ryujinx.Graphics.Nvdec.H264
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{
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struct H264BitStreamWriter
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{
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private const int BufferSize = 8;
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private readonly byte[] _workBuffer;
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private int _offset;
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private int _buffer;
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private int _bufferPos;
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public H264BitStreamWriter(byte[] workBuffer)
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{
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_workBuffer = workBuffer;
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_offset = 0;
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_buffer = 0;
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_bufferPos = 0;
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}
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public void WriteBit(bool value)
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{
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WriteBits(value ? 1 : 0, 1);
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}
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public void WriteBits(int value, int valueSize)
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{
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int valuePos = 0;
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int remaining = valueSize;
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while (remaining > 0)
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{
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int copySize = remaining;
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int free = GetFreeBufferBits();
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if (copySize > free)
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{
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copySize = free;
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}
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int mask = (1 << copySize) - 1;
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int srcShift = (valueSize - valuePos) - copySize;
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int dstShift = (BufferSize - _bufferPos) - copySize;
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_buffer |= ((value >> srcShift) & mask) << dstShift;
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valuePos += copySize;
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_bufferPos += copySize;
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remaining -= copySize;
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}
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}
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private int GetFreeBufferBits()
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{
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if (_bufferPos == BufferSize)
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{
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Flush();
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}
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return BufferSize - _bufferPos;
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}
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public void Flush()
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{
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if (_bufferPos != 0)
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{
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_workBuffer[_offset++] = (byte)_buffer;
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_buffer = 0;
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_bufferPos = 0;
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}
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}
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public void End()
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{
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WriteBit(true);
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Flush();
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}
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public Span<byte> AsSpan()
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{
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return new Span<byte>(_workBuffer).Slice(0, _offset);
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}
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public void WriteU(uint value, int valueSize) => WriteBits((int)value, valueSize);
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public void WriteSe(int value) => WriteExpGolombCodedInt(value);
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public void WriteUe(uint value) => WriteExpGolombCodedUInt(value);
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private void WriteExpGolombCodedInt(int value)
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{
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int sign = value <= 0 ? 0 : 1;
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if (value < 0)
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{
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value = -value;
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}
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value = (value << 1) - sign;
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WriteExpGolombCodedUInt((uint)value);
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}
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private void WriteExpGolombCodedUInt(uint value)
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{
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int size = 32 - BitOperations.LeadingZeroCount(value + 1);
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WriteBits(1, size);
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value -= (1u << (size - 1)) - 1;
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WriteBits((int)value, size - 1);
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}
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}
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}
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