Initial community commit

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

@@ -0,0 +1,62 @@
+/* Copyright (C) Teemu Suutari */
+
+#include "DLTADecode.hpp"
+
+#include "common/OverflowCheck.hpp"
+#include "common/Common.hpp"
+
+
+namespace ancient::internal
+{
+
+bool DLTADecode::detectHeaderXPK(uint32_t hdr) noexcept
+{
+	return hdr==FourCC("DLTA");
+}
+
+std::shared_ptr<XPKDecompressor> DLTADecode::create(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify)
+{
+	return std::make_shared<DLTADecode>(hdr,recursionLevel,packedData,state,verify);
+}
+
+DLTADecode::DLTADecode(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();
+}
+
+DLTADecode::~DLTADecode()
+{
+	// nothing needed
+}
+
+const std::string &DLTADecode::getSubName() const noexcept
+{
+	static std::string name="XPK-DLTA: Delta encoding";
+	return name;
+}
+
+void DLTADecode::decode(Buffer &bufferDest,const Buffer &bufferSrc,size_t offset,size_t size)
+{
+	if (OverflowCheck::sum(offset,size)>bufferSrc.size()) throw Buffer::OutOfBoundsError();
+	if (OverflowCheck::sum(offset,size)>bufferDest.size()) throw Buffer::OutOfBoundsError();
+	const uint8_t *src=bufferSrc.data()+offset;
+	uint8_t *dest=bufferDest.data()+offset;
+
+	uint8_t ctr=0;
+	for (size_t i=0;i<size;i++)
+	{
+		ctr+=src[i];
+		dest[i]=ctr;
+	}
+}
+
+
+void DLTADecode::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
+{
+	if (rawData.size()<_packedData.size()) throw Decompressor::DecompressionError();
+	decode(rawData,_packedData,0,_packedData.size());
+}
+
+}