Initial community commit

Src/external_dependencies/openmpt-trunk/include/ancient/src/LZW2Decompressor.cpp

@@ -0,0 +1,74 @@
+/* Copyright (C) Teemu Suutari */
+
+#include "LZW2Decompressor.hpp"
+#include "InputStream.hpp"
+#include "OutputStream.hpp"
+#include "common/Common.hpp"
+
+
+namespace ancient::internal
+{
+
+bool LZW2Decompressor::detectHeaderXPK(uint32_t hdr) noexcept
+{
+	return hdr==FourCC("LZW2") || hdr==FourCC("LZW3");
+}
+
+std::shared_ptr<XPKDecompressor> LZW2Decompressor::create(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify)
+{
+	return std::make_shared<LZW2Decompressor>(hdr,recursionLevel,packedData,state,verify);
+}
+
+LZW2Decompressor::LZW2Decompressor(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify) :
+	XPKDecompressor(recursionLevel),
+	_packedData(packedData)
+{
+	if (!detectHeaderXPK(hdr)) throw Decompressor::InvalidFormatError();
+	_ver=(hdr==FourCC("LZW2"))?2:3;
+}
+
+LZW2Decompressor::~LZW2Decompressor()
+{
+	// nothing needed
+}
+
+const std::string &LZW2Decompressor::getSubName() const noexcept
+{
+	static std::string name2="XPK-LZW2: LZW2 CyberYAFA compressor";
+	static std::string name3="XPK-LZW3: LZW3 CyberYAFA compressor";
+	return (_ver==2)?name2:name3;
+}
+
+void LZW2Decompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
+{
+	ForwardInputStream inputStream(_packedData,0,_packedData.size());
+	LSBBitReader<ForwardInputStream> bitReader(inputStream);
+	auto readBit=[&]()->uint32_t
+	{
+		return bitReader.readBitsBE32(1);
+	};
+	auto readByte=[&]()->uint8_t
+	{
+		return inputStream.readByte();
+	};
+
+	ForwardOutputStream outputStream(rawData,0,rawData.size());
+
+	while (!outputStream.eof())
+	{
+		if (!readBit())
+		{
+			outputStream.writeByte(readByte());
+		} else {
+			uint32_t distance=uint32_t(readByte())<<8;
+			distance|=uint32_t(readByte());
+			if (!distance) throw Decompressor::DecompressionError();
+			distance=65536-distance;
+			uint32_t count=uint32_t(readByte())+4;
+
+			outputStream.copy(distance,count);
+		}
+	}
+}
+
+}