llvm/llvm/include/llvm/DebugInfo/MSF/MSFCommon.h

//===- MSFCommon.h - Common types and functions for MSF files ---*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_DEBUGINFO_MSF_MSFCOMMON_H
#define LLVM_DEBUGINFO_MSF_MSFCOMMON_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MathExtras.h"
#include <cstdint>
#include <vector>

namespace llvm {
namespace msf {

static const char Magic[] = …;

// The superblock is overlaid at the beginning of the file (offset 0).
// It starts with a magic header and is followed by information which
// describes the layout of the file system.
struct SuperBlock { … };

struct MSFLayout { … };

/// Describes the layout of a stream in an MSF layout.  A "stream" here
/// is defined as any logical unit of data which may be arranged inside the MSF
/// file as a sequence of (possibly discontiguous) blocks.  When we want to read
/// from a particular MSF Stream, we fill out a stream layout structure and the
/// reader uses it to determine which blocks in the underlying MSF file contain
/// the data, so that it can be pieced together in the right order.
class MSFStreamLayout { … };

/// Determine the layout of the FPM stream, given the MSF layout.  An FPM
/// stream spans 1 or more blocks, each at equally spaced intervals throughout
/// the file.
MSFStreamLayout getFpmStreamLayout(const MSFLayout &Msf,
                                   bool IncludeUnusedFpmData = false,
                                   bool AltFpm = false);

inline bool isValidBlockSize(uint32_t Size) { … }

/// Given the specified block size, returns the maximum possible file size.
/// Block Size  |  Max File Size
/// <= 4096     |      4GB
///    8192     |      8GB
///   16384     |      16GB
///   32768     |      32GB
/// \p Size - the block size of the MSF
inline uint64_t getMaxFileSizeFromBlockSize(uint32_t Size) { … }

// Super Block, Fpm0, Fpm1, and Block Map
inline uint32_t getMinimumBlockCount() { … }

// Super Block, Fpm0, and Fpm1 are reserved.  The Block Map, although required
// need not be at block 3.
inline uint32_t getFirstUnreservedBlock() { … }

inline uint64_t bytesToBlocks(uint64_t NumBytes, uint64_t BlockSize) { … }

inline uint64_t blockToOffset(uint64_t BlockNumber, uint64_t BlockSize) { … }

inline uint32_t getFpmIntervalLength(const MSFLayout &L) { … }

/// Given an MSF with the specified block size and number of blocks, determine
/// how many pieces the specified Fpm is split into.
/// \p BlockSize - the block size of the MSF
/// \p NumBlocks - the total number of blocks in the MSF
/// \p IncludeUnusedFpmData - When true, this will count every block that is
///    both in the file and matches the form of an FPM block, even if some of
///    those FPM blocks are unused (a single FPM block can describe the
///    allocation status of up to 32,767 blocks, although one appears only
///    every 4,096 blocks).  So there are 8x as many blocks that match the
///    form as there are blocks that are necessary to describe the allocation
///    status of the file.  When this parameter is false, these extraneous
///    trailing blocks are not counted.
inline uint32_t getNumFpmIntervals(uint32_t BlockSize, uint32_t NumBlocks,
                                   bool IncludeUnusedFpmData, int FpmNumber) { … }

inline uint32_t getNumFpmIntervals(const MSFLayout &L,
                                   bool IncludeUnusedFpmData = false,
                                   bool AltFpm = false) { … }

Error validateSuperBlock(const SuperBlock &SB);

} // end namespace msf
} // end namespace llvm

#endif // LLVM_DEBUGINFO_MSF_MSFCOMMON_H