1 files changed, 115 insertions, 0 deletions
diff --git a/thirdparty/raw_pdb/src/PDB_DirectMSFStream.cpp b/thirdparty/raw_pdb/src/PDB_DirectMSFStream.cpp
new file mode 100644
index 000000000..442dc7637
--- /dev/null
+++ b/thirdparty/raw_pdb/src/PDB_DirectMSFStream.cpp
@@ -0,0 +1,115 @@
+// Copyright 2011-2022, Molecular Matters GmbH <[email protected]>
+// See LICENSE.txt for licensing details (2-clause BSD License: https://opensource.org/licenses/BSD-2-Clause)
+
+#include "PDB_PCH.h"
+#include "PDB_DirectMSFStream.h"
+#include "Foundation/PDB_PointerUtil.h"
+#include "Foundation/PDB_BitUtil.h"
+#include "Foundation/PDB_Assert.h"
+#include "Foundation/PDB_CRT.h"
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB::DirectMSFStream::DirectMSFStream(void) PDB_NO_EXCEPT
+	: m_data(nullptr)
+	, m_blockIndices(nullptr)
+	, m_blockSize(0u)
+	, m_size(0u)
+	, m_blockSizeLog2(0u)
+{
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB::DirectMSFStream::DirectMSFStream(const void* data, uint32_t blockSize, const uint32_t* blockIndices, uint32_t streamSize) PDB_NO_EXCEPT
+	: m_data(data)
+	, m_blockIndices(blockIndices)
+	, m_blockSize(blockSize)
+	, m_size(streamSize)
+	, m_blockSizeLog2(BitUtil::FindFirstSetBit(blockSize))
+{
+	PDB_ASSERT(BitUtil::IsPowerOfTwo(blockSize), "MSF block size must be a power of two.");
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+void PDB::DirectMSFStream::ReadAtOffset(void* destination, size_t size, size_t offset) const PDB_NO_EXCEPT
+{
+	PDB_ASSERT(destination != nullptr, "Destination buffer not set");
+	PDB_ASSERT(offset + size <= m_size, "Not enough data left to read.");
+
+	// work out which block and offset within the block the read offset corresponds to
+	size_t blockIndex = offset >> m_blockSizeLog2;
+	const size_t offsetWithinBlock = offset & (m_blockSize - 1u);
+
+	// work out the offset within the data based on the block indices
+	size_t offsetWithinData = (static_cast<size_t>(m_blockIndices[blockIndex]) << m_blockSizeLog2) + offsetWithinBlock;
+	const size_t bytesLeftInBlock = m_blockSize - offsetWithinBlock;
+
+	if (bytesLeftInBlock >= size)
+	{
+		// fast path, all the data can be read in one go
+		const void* const sourceData = Pointer::Offset<const void*>(m_data, offsetWithinData);
+		memcpy(destination, sourceData, size);
+	}
+	else
+	{
+		// slower path, data is scattered across several blocks.
+		// read remaining bytes in current block first.
+		{
+			const void* const sourceData = Pointer::Offset<const void*>(m_data, offsetWithinData);
+			memcpy(destination, sourceData, bytesLeftInBlock);
+		}
+
+		// read remaining bytes from blocks
+		size_t bytesLeftToRead = size - bytesLeftInBlock;
+		while (bytesLeftToRead != 0u)
+		{
+			// advance to the next block
+			++blockIndex;
+			offsetWithinData = static_cast<size_t>(m_blockIndices[blockIndex]) << m_blockSizeLog2;
+
+			void* const destinationData = Pointer::Offset<void*>(destination, size - bytesLeftToRead);
+			const void* const sourceData = Pointer::Offset<const void*>(m_data, offsetWithinData);
+
+			if (bytesLeftToRead > m_blockSize)
+			{
+				// copy a whole block at once
+				memcpy(destinationData, sourceData, m_blockSize);
+				bytesLeftToRead -= m_blockSize;
+			}
+			else
+			{
+				// copy remaining bytes
+				memcpy(destinationData, sourceData, bytesLeftToRead);
+				bytesLeftToRead -= bytesLeftToRead;
+			}
+		}
+	}
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::DirectMSFStream::IndexAndOffset PDB::DirectMSFStream::GetBlockIndexForOffset(uint32_t offset) const PDB_NO_EXCEPT
+{
+	// work out which block and offset within the block the offset corresponds to
+	const uint32_t blockIndex = offset >> m_blockSizeLog2;
+	const uint32_t offsetWithinBlock = offset & (m_blockSize - 1u);
+
+	return IndexAndOffset { blockIndex, offsetWithinBlock };
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD size_t PDB::DirectMSFStream::GetDataOffsetForIndexAndOffset(const IndexAndOffset& indexAndOffset) const PDB_NO_EXCEPT
+{
+	// work out the offset within the data based on the block indices
+	const size_t offsetWithinData = (static_cast<size_t>(m_blockIndices[indexAndOffset.index]) << m_blockSizeLog2) + indexAndOffset.offsetWithinBlock;
+
+	return offsetWithinData;
+}