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Ryujinx/Ryujinx.Core/Loaders/Compression/Lz4.cs

78 lines
No EOL
1.9 KiB
C#

using System;
namespace Ryujinx.Core.Loaders.Compression
{
static class Lz4
{
public static byte[] Decompress(byte[] Cmp, int DecLength)
{
byte[] Dec = new byte[DecLength];
int CmpPos = 0;
int DecPos = 0;
int GetLength(int Length)
{
byte Sum;
if (Length == 0xf)
{
do
{
Length += (Sum = Cmp[CmpPos++]);
}
while (Sum == 0xff);
}
return Length;
}
do
{
byte Token = Cmp[CmpPos++];
int EncCount = (Token >> 0) & 0xf;
int LitCount = (Token >> 4) & 0xf;
//Copy literal chunck
LitCount = GetLength(LitCount);
Buffer.BlockCopy(Cmp, CmpPos, Dec, DecPos, LitCount);
CmpPos += LitCount;
DecPos += LitCount;
if (CmpPos >= Cmp.Length)
{
break;
}
//Copy compressed chunck
int Back = Cmp[CmpPos++] << 0 |
Cmp[CmpPos++] << 8;
EncCount = GetLength(EncCount) + 4;
int EncPos = DecPos - Back;
if (EncCount <= Back)
{
Buffer.BlockCopy(Dec, EncPos, Dec, DecPos, EncCount);
DecPos += EncCount;
}
else
{
while (EncCount-- > 0)
{
Dec[DecPos++] = Dec[EncPos++];
}
}
}
while (CmpPos < Cmp.Length &&
DecPos < Dec.Length);
return Dec;
}
}
}