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reduce dynamic stackallocs in unpackv1

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This commit is contained in:
Adam Hathcock
2025-10-22 08:32:19 +01:00
parent c0612547eb
commit 6de738ff17
1 changed files with 24 additions and 15 deletions
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39
src/SharpCompress/Compressors/Rar/UnpackV1/Unpack.cs
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@@ -1028,7 +1028,7 @@ internal sealed partial class Unpack : BitInput, IRarUnpack, IDisposable
vmCode.Add((byte)(GetBits() >> 8));
AddBits(8);
}
return (AddVMCode(FirstByte, vmCode, Length));
return AddVMCode(FirstByte, vmCode);
}
private bool ReadVMCodePPM()
@@ -1073,10 +1073,10 @@ internal sealed partial class Unpack : BitInput, IRarUnpack, IDisposable
}
vmCode.Add((byte)Ch); // VMCode[I]=Ch;
}
return (AddVMCode(FirstByte, vmCode, Length));
return AddVMCode(FirstByte, vmCode);
}
private bool AddVMCode(int firstByte, List<byte> vmCode, int length)
private bool AddVMCode(int firstByte, List<byte> vmCode)
{
var Inp = new BitInput();
Inp.InitBitInput();
@@ -1199,19 +1199,28 @@ internal sealed partial class Unpack : BitInput, IRarUnpack, IDisposable
{
return (false);
}
Span<byte> VMCode = stackalloc byte[VMCodeSize];
for (var I = 0; I < VMCodeSize; I++)
{
if (Inp.Overflow(3))
{
return (false);
}
VMCode[I] = (byte)(Inp.GetBits() >> 8);
Inp.AddBits(8);
}
// VM.Prepare(&VMCode[0],VMCodeSize,&Filter->Prg);
rarVM.prepare(VMCode, VMCodeSize, Filter.Program);
var VMCode = ArrayPool<byte>.Shared.Rent(VMCodeSize);
try
{
for (var I = 0; I < VMCodeSize; I++)
{
if (Inp.Overflow(3))
{
return (false);
}
VMCode[I] = (byte)(Inp.GetBits() >> 8);
Inp.AddBits(8);
}
// VM.Prepare(&VMCode[0],VMCodeSize,&Filter->Prg);
rarVM.prepare(VMCode, VMCodeSize, Filter.Program);
}
finally
{
ArrayPool<byte>.Shared.Return(VMCode);
}
}
StackFilter.Program.AltCommands = Filter.Program.Commands; // StackFilter->Prg.AltCmd=&Filter->Prg.Cmd[0];
StackFilter.Program.CommandCount = Filter.Program.CommandCount;