Add unpacktool

unpacktool/LZWDecompressor.cpp

@@ -0,0 +1,81 @@
+#include "LZWDecompressor.h"
+
+#include "CSInputBuffer.h"
+
+LZWDecompressor::LZWDecompressor(int compressFlags)
+	: input(nullptr)
+	, compressFlags(compressFlags)
+	, blockmode(false)
+	, lzw(nullptr)
+	, symbolcounter(0)
+	, buffer(nullptr)
+	, bufferend(nullptr)
+{
+}
+
+LZWDecompressor::~LZWDecompressor()
+{
+	FreeLZW(lzw);
+}
+
+
+bool LZWDecompressor::Reset(CSInputBuffer *input, size_t compressedSize, size_t decompressedSize)
+{
+	this->input = input;
+	blockmode = (compressFlags & 0x80) != 0;
+	lzw = AllocLZW(1 << (compressFlags & 0x1f), blockmode ? 1 : 0);
+
+	return true;
+}
+
+bool LZWDecompressor::ReadBytes(void *dest, size_t numBytes)
+{
+	uint8_t *nextByte = static_cast<uint8_t*>(dest);
+
+	while (numBytes--)
+	{
+		if (buffer >= bufferend)
+		{
+			unsigned int symbol;
+			for (;;)
+			{
+				bool atEOF;
+				if (!CSInputAtEOF(input, atEOF))
+					return false;
+
+				if (atEOF)
+					return false;
+
+				if (!CSInputNextBitStringLE(input, LZWSuggestedSymbolSize(lzw), symbol))
+					return false;
+
+				symbolcounter++;
+				if (symbol == 256 && blockmode)
+				{
+					// Skip garbage data after a clear. God damn, this is dumb.
+					int symbolsize = LZWSuggestedSymbolSize(lzw);
+					if (symbolcounter % 8)
+					{
+						if (!CSInputSkipBitsLE(input, symbolsize*(8 - symbolcounter % 8)))
+							return false;
+					}
+					ClearLZWTable(lzw);
+					symbolcounter = 0;
+				}
+				else
+					break;
+			}
+
+			if (NextLZWSymbol(lzw, symbol) == LZWInvalidCodeError)
+				return false;
+
+			int n = LZWOutputToInternalBuffer(lzw);
+			buffer = LZWInternalBuffer(lzw);
+			bufferend = buffer + n;
+		}
+
+		*nextByte++ = *buffer++;
+	}
+
+	return true;
+}