Initial community commit

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

@@ -0,0 +1,113 @@
+/* Copyright (C) Teemu Suutari */
+
+#include "InputStream.hpp"
+// for exceptions
+#include "Decompressor.hpp"
+#include "common/OverflowCheck.hpp"
+
+
+namespace ancient::internal
+{
+
+ForwardInputStream::ForwardInputStream(const Buffer &buffer,size_t startOffset,size_t endOffset,bool allowOverrun) :
+	_bufPtr(buffer.data()),
+	_currentOffset(startOffset),
+	_endOffset(endOffset),
+	_allowOverrun(allowOverrun)
+{
+	if (_currentOffset>_endOffset || _currentOffset>buffer.size() || _endOffset>buffer.size()) throw Decompressor::DecompressionError();
+}
+
+ForwardInputStream::~ForwardInputStream()
+{
+	// nothing needed
+}
+
+uint8_t ForwardInputStream::readByte()
+{
+	if (_currentOffset>=_endOffset)
+	{
+		if (_allowOverrun)
+		{
+			_currentOffset++;
+			return 0;
+		}
+		throw Decompressor::DecompressionError();
+	}
+	uint8_t ret=_bufPtr[_currentOffset++];
+	if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
+	return ret;
+}
+
+const uint8_t *ForwardInputStream::consume(size_t bytes,uint8_t *buffer)
+{
+	if (OverflowCheck::sum(_currentOffset,bytes)>_endOffset)
+	{
+		if (_allowOverrun && buffer)
+		{
+			for (size_t i=0;i<bytes;i++)
+			{
+				buffer[i]=(_currentOffset<_endOffset)?_bufPtr[_currentOffset]:0;
+				_currentOffset++;
+			}
+			return buffer;
+		}
+		throw Decompressor::DecompressionError();
+	}
+	const uint8_t *ret=&_bufPtr[_currentOffset];
+	_currentOffset+=bytes;
+	if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
+	return ret;
+}
+
+BackwardInputStream::BackwardInputStream(const Buffer &buffer,size_t startOffset,size_t endOffset,bool allowOverrun) :
+	_bufPtr(buffer.data()),
+	_currentOffset(endOffset),
+	_endOffset(startOffset),
+	_allowOverrun(allowOverrun)
+{
+	if (_currentOffset<_endOffset || _currentOffset>buffer.size() || _endOffset>buffer.size()) throw Decompressor::DecompressionError();
+}
+
+BackwardInputStream::~BackwardInputStream()
+{
+	// nothing needed
+}
+
+uint8_t BackwardInputStream::readByte()
+{
+	if (_currentOffset<=_endOffset)
+	{
+		if (_allowOverrun)
+		{
+			--_currentOffset;
+			return 0;
+		}
+		throw Decompressor::DecompressionError();
+	}
+	uint8_t ret=_bufPtr[--_currentOffset];
+	if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
+	return ret;
+}
+
+const uint8_t *BackwardInputStream::consume(size_t bytes,uint8_t *buffer)
+{
+	if (_currentOffset<OverflowCheck::sum(_endOffset,bytes))
+	{
+		if (_allowOverrun && buffer)
+		{
+			for (size_t i=bytes;i;i--)
+			{
+				buffer[i-1]=(_currentOffset>_endOffset)?_bufPtr[_currentOffset-1]:0;
+				--_currentOffset;
+			}
+			return buffer;
+		}
+		throw Decompressor::DecompressionError();
+	}
+	_currentOffset-=bytes;
+	if (_linkedInputStream) _linkedInputStream->setOffset(_currentOffset);
+	return &_bufPtr[_currentOffset];
+}
+
+}