[flang] Implement byte-swapped external unformatted I/O in runtime

[klausler]

Summary

Add SetConvert() to the OPEN statement's runtime API.
Add ByteswapOption() to the main program's runtime API.
Check a $FORT_CONVERT environment variable, too, for
a swapping specifier.

flang/runtime/environment.h

 //===-- runtime/environment.h -----------------------------------*- 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 FORTRAN_RUNTIME_ENVIRONMENT_H_
 #define FORTRAN_RUNTIME_ENVIRONMENT_H_
 
 #include "flang/Decimal/decimal.h"
+#include <optional>
 
 namespace Fortran::runtime {
+
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+constexpr bool isHostLittleEndian{false};
+#elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+constexpr bool isHostLittleEndian{true};
+#else
+#error host endianness is not known
+#endif
+
+// External unformatted I/O data conversions
+enum class Convert { Unknown, Native, LittleEndian, BigEndian, Swap };
+
+std::optional<Convert> GetConvertFromString(const char *, std::size_t);
+
 struct ExecutionEnvironment {
   void Configure(int argc, const char *argv[], const char *envp[]);
 
   int argc;
   const char **argv;
   const char **envp;
   int listDirectedOutputLineLengthLimit;
   enum decimal::FortranRounding defaultOutputRoundingMode;
+  Convert conversion;
 };
 extern ExecutionEnvironment executionEnvironment;
 } // namespace Fortran::runtime
 
 #endif // FORTRAN_RUNTIME_ENVIRONMENT_H_

flang/runtime/environment.cpp

 //===-- runtime/environment.cpp ---------------------------------*- 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "environment.h"
+#include "tools.h"
 #include <cstdio>
 #include <cstdlib>
+#include <cstring>
 #include <limits>
 
 namespace Fortran::runtime {
+
 ExecutionEnvironment executionEnvironment;
 
+std::optional<Convert> GetConvertFromString(const char *x, std::size_t n) {
+  static const char *keywords[]{
+      "UNKNOWN", "NATIVE", "LITTLE_ENDIAN", "BIG_ENDIAN", "SWAP", nullptr};
+  switch (IdentifyValue(x, n, keywords)) {
+  case 0:
+    return Convert::Unknown;
+  case 1:
+    return Convert::Native;
+  case 2:
+    return Convert::LittleEndian;
+  case 3:
+    return Convert::BigEndian;
+  case 4:
+    return Convert::Swap;
+  default:
+    return std::nullopt;
+  }
+}
+
 void ExecutionEnvironment::Configure(
     int ac, const char *av[], const char *env[]) {
   argc = ac;
   argv = av;
   envp = env;
   listDirectedOutputLineLengthLimit = 79; // PGI default
   defaultOutputRoundingMode =
       decimal::FortranRounding::RoundNearest; // RP(==RN)
+  conversion = Convert::Unknown;
 
   if (auto *x{std::getenv("FORT_FMT_RECL")}) {
     char *end;
     auto n{std::strtol(x, &end, 10)};
     if (n > 0 && n < std::numeric_limits<int>::max() && *end == '\0') {
       listDirectedOutputLineLengthLimit = n;
     } else {
       std::fprintf(
           stderr, "Fortran runtime: FORT_FMT_RECL=%s is invalid; ignored\n", x);
     }
   }
 
+  if (auto *x{std::getenv("FORT_CONVERT")}) {
+    if (auto convert{GetConvertFromString(x, std::strlen(x))}) {
+      conversion = *convert;
+    } else {
+      std::fprintf(
+          stderr, "Fortran runtime: FORT_CONVERT=%s is invalid; ignored\n", x);
+    }
+  }
+
   // TODO: Set RP/ROUND='PROCESSOR_DEFINED' from environment
 }
 } // namespace Fortran::runtime

flang/runtime/format.h

struct DataEdit {
   int repeat{1};
 };
 
 // FormatControl<A> requires that A have these member functions;
 // these default implementations just crash if called.
 struct DefaultFormatControlCallbacks : public IoErrorHandler {
   using IoErrorHandler::IoErrorHandler;
   DataEdit GetNextDataEdit(int = 1);
-  bool Emit(const char *, std::size_t);
+  bool Emit(const char *, std::size_t, std::size_t elementBytes = 0);
   bool Emit(const char16_t *, std::size_t);
   bool Emit(const char32_t *, std::size_t);
   std::optional<char32_t> GetCurrentChar();
   bool AdvanceRecord(int = 1);
   void BackspaceRecord();
   void HandleAbsolutePosition(std::int64_t);
   void HandleRelativePosition(std::int64_t);
 };

flang/runtime/format.cpp

 
 namespace Fortran::runtime::io {
 
 DataEdit DefaultFormatControlCallbacks::GetNextDataEdit(int) {
   Crash("DefaultFormatControlCallbacks::GetNextDataEdit() called for "
         "non-formatted I/O statement");
   return {};
 }
-bool DefaultFormatControlCallbacks::Emit(const char *, std::size_t) {
+bool DefaultFormatControlCallbacks::Emit(
+    const char *, std::size_t, std::size_t) {
   Crash("DefaultFormatControlCallbacks::Emit(char) called for non-output I/O "
         "statement");
   return {};
 }
 bool DefaultFormatControlCallbacks::Emit(const char16_t *, std::size_t) {
   Crash("DefaultFormatControlCallbacks::Emit(char16_t) called for non-output "
         "I/O statement");
   return {};

flang/runtime/io-api.h

 // These functions return false when the I/O statement has encountered an
 // error or end-of-file/record condition that the caller has indicated
 // should not cause termination of the image by the runtime library.
 // Once the statement has encountered an error, all following items will be
 // ignored and also return false; but compiled code should check for errors
 // and avoid the following items when they might crash.
 bool IONAME(OutputDescriptor)(Cookie, const Descriptor &);
 bool IONAME(InputDescriptor)(Cookie, const Descriptor &);
-bool IONAME(OutputUnformattedBlock)(Cookie, const char *, std::size_t);
-bool IONAME(InputUnformattedBlock)(Cookie, char *, std::size_t);
+bool IONAME(OutputUnformattedBlock)(
+    Cookie, const char *, std::size_t, std::size_t elementBytes);
+bool IONAME(InputUnformattedBlock)(
+    Cookie, char *, std::size_t, std::size_t elementBytes);
 bool IONAME(OutputInteger64)(Cookie, std::int64_t);
 bool IONAME(InputInteger)(Cookie, std::int64_t &, int kind = 8);
 bool IONAME(OutputReal32)(Cookie, float);
 bool IONAME(InputReal32)(Cookie, float &);
 bool IONAME(OutputReal64)(Cookie, double);
 bool IONAME(InputReal64)(Cookie, double &);
 bool IONAME(OutputComplex32)(Cookie, float, float);
 bool IONAME(OutputComplex64)(Cookie, double, double);
 bool IONAME(OutputAscii)(Cookie, const char *, std::size_t);
 bool IONAME(InputAscii)(Cookie, char *, std::size_t);
 bool IONAME(OutputLogical)(Cookie, bool);
 bool IONAME(InputLogical)(Cookie, bool &);
 
 // Additional specifier interfaces for the connection-list of
 // on OPEN statement (only).  SetBlank(), SetDecimal(),
 // SetDelim(), GetIoMsg(), SetPad(), SetRound(), & SetSign()
 // are also acceptable for OPEN.
 // ACCESS=SEQUENTIAL, DIRECT, STREAM
 bool IONAME(SetAccess)(Cookie, const char *, std::size_t);
 // ACTION=READ, WRITE, or READWRITE
 bool IONAME(SetAction)(Cookie, const char *, std::size_t);
 // ASYNCHRONOUS=YES, NO
 bool IONAME(SetAsynchronous)(Cookie, const char *, std::size_t);
+// CONVERT=NATIVE, LITTLE_ENDIAN, BIG_ENDIAN, or SWAP
+bool IONAME(SetConvert)(Cookie, const char *, std::size_t);
 // ENCODING=UTF-8, DEFAULT
 bool IONAME(SetEncoding)(Cookie, const char *, std::size_t);
 // FORM=FORMATTED, UNFORMATTED
 bool IONAME(SetForm)(Cookie, const char *, std::size_t);
 // POSITION=ASIS, REWIND, APPEND
 bool IONAME(SetPosition)(Cookie, const char *, std::size_t);
 bool IONAME(SetRecl)(Cookie, std::size_t); // RECL=
 

flang/runtime/io-api.cpp

case 1:
     return true;
   default:
     open->SignalError(IostatErrorInKeyword, "Invalid ASYNCHRONOUS='%.*s'",
         static_cast<int>(length), keyword);
     return false;
   }
 }
 
+bool IONAME(SetConvert)(
+    Cookie cookie, const char *keyword, std::size_t length) {
+  IoStatementState &io{*cookie};
+  auto *open{io.get_if<OpenStatementState>()};
+  if (!open) {
+    io.GetIoErrorHandler().Crash(
+        "SetConvert() called when not in an OPEN statement");
+  }
+  if (auto convert{GetConvertFromString(keyword, length)}) {
+    open->set_convert(*convert);
+    return true;
+  } else {
+    open->SignalError(IostatErrorInKeyword, "Invalid CONVERT='%.*s'",
+        static_cast<int>(length), keyword);
+    return false;
+  }
+}
+
 bool IONAME(SetEncoding)(
     Cookie cookie, const char *keyword, std::size_t length) {
   IoStatementState &io{*cookie};
   auto *open{io.get_if<OpenStatementState>()};
   if (!open) {
     io.GetIoErrorHandler().Crash(
         "SetEncoding() called when not in an OPEN statement");
   }

 
 // Data transfers
 
 bool IONAME(OutputDescriptor)(Cookie cookie, const Descriptor &) {
   IoStatementState &io{*cookie};
   io.GetIoErrorHandler().Crash("OutputDescriptor: not yet implemented"); // TODO
 }
 
-bool IONAME(OutputUnformattedBlock)(
-    Cookie cookie, const char *x, std::size_t length) {
+bool IONAME(InputDescriptor)(Cookie cookie, const Descriptor &) {
+  IoStatementState &io{*cookie};
+  io.GetIoErrorHandler().Crash("InputDescriptor: not yet implemented"); // TODO
+}
+
+bool IONAME(OutputUnformattedBlock)(Cookie cookie, const char *x,
+    std::size_t length, std::size_t elementBytes) {
   IoStatementState &io{*cookie};
   if (auto *unf{io.get_if<UnformattedIoStatementState<Direction::Output>>()}) {
-    return unf->Emit(x, length);
+    return unf->Emit(x, length, elementBytes);
   }
   io.GetIoErrorHandler().Crash("OutputUnformattedBlock() called for an I/O "
                                "statement that is not unformatted output");
   return false;
 }
 
-bool IONAME(InputUnformattedBlock)(Cookie cookie, char *x, std::size_t length) {
+bool IONAME(InputUnformattedBlock)(
+    Cookie cookie, char *x, std::size_t length, std::size_t elementBytes) {
   IoStatementState &io{*cookie};
   if (auto *unf{io.get_if<UnformattedIoStatementState<Direction::Input>>()}) {
-    return unf->Receive(x, length);
+    return unf->Receive(x, length, elementBytes);
   }
   io.GetIoErrorHandler().Crash("InputUnformattedBlock() called for an I/O "
                                "statement that is not unformatted output");
   return false;
 }
 
 bool IONAME(OutputInteger64)(Cookie cookie, std::int64_t n) {
   IoStatementState &io{*cookie};

flang/runtime/io-stmt.h

public:
   template <typename A> explicit IoStatementState(A &x) : u_{x} {}
 
   // These member functions each project themselves into the active alternative.
   // They're used by per-data-item routines in the I/O API (e.g., OutputReal64)
   // to interact with the state of the I/O statement in progress.
   // This design avoids virtual member functions and function pointers,
   // which may not have good support in some runtime environments.
   std::optional<DataEdit> GetNextDataEdit(int = 1);
-  bool Emit(const char *, std::size_t);
+  bool Emit(const char *, std::size_t, std::size_t elementBytes = 0);
   std::optional<char32_t> GetCurrentChar(); // vacant after end of record
   bool AdvanceRecord(int = 1);
   void BackspaceRecord();
   void HandleRelativePosition(std::int64_t);
   int EndIoStatement();
   ConnectionState &GetConnectionState();
   IoErrorHandler &GetIoErrorHandler() const;
   ExternalFileUnit *GetExternalFileUnit() const; // null if internal unit
public:
   using CharType = CHAR;
   using Buffer =
       std::conditional_t<DIR == Direction::Input, const CharType *, CharType *>;
   InternalIoStatementState(Buffer, std::size_t,
       const char *sourceFile = nullptr, int sourceLine = 0);
   InternalIoStatementState(
       const Descriptor &, const char *sourceFile = nullptr, int sourceLine = 0);
   int EndIoStatement();
-  bool Emit(const CharType *, std::size_t chars /* not bytes */);
+  bool Emit(const CharType *, std::size_t chars /* not necessarily bytes */,
+      std::size_t elementBytes = 0);
   std::optional<char32_t> GetCurrentChar();
   bool AdvanceRecord(int = 1);
   void BackspaceRecord();
   ConnectionState &GetConnectionState() { return unit_; }
   MutableModes &mutableModes() { return unit_.modes; }
   void HandleRelativePosition(std::int64_t);
   void HandleAbsolutePosition(std::int64_t);
 

 };
 
 template <Direction DIR>
 class ExternalIoStatementState : public ExternalIoStatementBase,
                                  public IoDirectionState<DIR> {
 public:
   using ExternalIoStatementBase::ExternalIoStatementBase;
   int EndIoStatement();
-  bool Emit(const char *, std::size_t);
+  bool Emit(const char *, std::size_t, std::size_t elementBytes = 0);
   bool Emit(const char16_t *, std::size_t chars /* not bytes */);
   bool Emit(const char32_t *, std::size_t chars /* not bytes */);
   std::optional<char32_t> GetCurrentChar();
   bool AdvanceRecord(int = 1);
   void BackspaceRecord();
   void HandleRelativePosition(std::int64_t);
   void HandleAbsolutePosition(std::int64_t);
 };
public:
   using ExternalIoStatementState<DIR>::ExternalIoStatementState;
   using ListDirectedStatementState<DIR>::GetNextDataEdit;
 };
 
 template <Direction DIR>
 class UnformattedIoStatementState : public ExternalIoStatementState<DIR> {
 public:
   using ExternalIoStatementState<DIR>::ExternalIoStatementState;
-  bool Receive(char *, std::size_t);
+  bool Receive(char *, std::size_t, std::size_t elementBytes = 0);
+  bool Emit(const char *, std::size_t, std::size_t elementBytes = 0);
   int EndIoStatement();
 };
 
 class OpenStatementState : public ExternalIoStatementBase {
 public:
   OpenStatementState(ExternalFileUnit &unit, bool wasExtant,
       const char *sourceFile = nullptr, int sourceLine = 0)
       : ExternalIoStatementBase{unit, sourceFile, sourceLine}, wasExtant_{
                                                                    wasExtant} {}
   bool wasExtant() const { return wasExtant_; }
   void set_status(OpenStatus status) { status_ = status; } // STATUS=
   void set_path(const char *, std::size_t, int kind); // FILE=
   void set_position(Position position) { position_ = position; } // POSITION=
   void set_action(Action action) { action_ = action; } // ACTION=
+  void set_convert(Convert convert) { convert_ = convert; } // CONVERT=
   int EndIoStatement();
 
 private:
   bool wasExtant_;
   std::optional<OpenStatus> status_;
   Position position_{Position::AsIs};
   std::optional<Action> action_;
+  Convert convert_{Convert::Native};
   OwningPtr<char> path_;
   std::size_t pathLength_;
 };
 
 class CloseStatementState : public ExternalIoStatementBase {
 public:
   CloseStatementState(ExternalFileUnit &unit, const char *sourceFile = nullptr,
       int sourceLine = 0)

flang/runtime/io-stmt.cpp

 
 template <Direction DIR, typename CHAR>
 InternalIoStatementState<DIR, CHAR>::InternalIoStatementState(
     const Descriptor &d, const char *sourceFile, int sourceLine)
     : IoStatementBase{sourceFile, sourceLine}, unit_{d, *this} {}
 
 template <Direction DIR, typename CHAR>
 bool InternalIoStatementState<DIR, CHAR>::Emit(
-    const CharType *data, std::size_t chars) {
+    const CharType *data, std::size_t chars, std::size_t /*elementBytes*/) {
   if constexpr (DIR == Direction::Input) {
     Crash("InternalIoStatementState<Direction::Input>::Emit() called");
     return false;
   }
   return unit_.Emit(data, chars, *this);
 }
 
 template <Direction DIR, typename CHAR>

 }
 
 int OpenStatementState::EndIoStatement() {
   if (wasExtant_ && status_ && *status_ != OpenStatus::Old) {
     SignalError("OPEN statement for connected unit may not have STATUS= other "
                 "than 'OLD'");
   }
   unit().OpenUnit(status_.value_or(OpenStatus::Unknown), action_, position_,
-      std::move(path_), pathLength_, *this);
+      std::move(path_), pathLength_, convert_, *this);
   return ExternalIoStatementBase::EndIoStatement();
 }
 
 int CloseStatementState::EndIoStatement() {
   int result{ExternalIoStatementBase::EndIoStatement()};
   unit().CloseUnit(status_, *this);
   unit().DestroyClosed();
   return result;
template <Direction DIR> int ExternalIoStatementState<DIR>::EndIoStatement() {
   }
   if constexpr (DIR == Direction::Output) {
     unit().FlushIfTerminal(*this);
   }
   return ExternalIoStatementBase::EndIoStatement();
 }
 
 template <Direction DIR>
-bool ExternalIoStatementState<DIR>::Emit(const char *data, std::size_t chars) {
+bool ExternalIoStatementState<DIR>::Emit(
+    const char *data, std::size_t bytes, std::size_t elementBytes) {
   if constexpr (DIR == Direction::Input) {
     Crash("ExternalIoStatementState::Emit(char) called for input statement");
   }
-  return unit().Emit(data, chars * sizeof(*data), *this);
+  return unit().Emit(data, bytes, elementBytes, *this);
 }
 
 template <Direction DIR>
 bool ExternalIoStatementState<DIR>::Emit(
     const char16_t *data, std::size_t chars) {
   if constexpr (DIR == Direction::Input) {
     Crash(
         "ExternalIoStatementState::Emit(char16_t) called for input statement");
   }
   // TODO: UTF-8 encoding
   return unit().Emit(
-      reinterpret_cast<const char *>(data), chars * sizeof(*data), *this);
+      reinterpret_cast<const char *>(data), chars * sizeof *data, static_cast<int>(sizeof *data), *this);
 }
 
 template <Direction DIR>
 bool ExternalIoStatementState<DIR>::Emit(
     const char32_t *data, std::size_t chars) {
   if constexpr (DIR == Direction::Input) {
     Crash(
         "ExternalIoStatementState::Emit(char32_t) called for input statement");
   }
   // TODO: UTF-8 encoding
   return unit().Emit(
-      reinterpret_cast<const char *>(data), chars * sizeof(*data), *this);
+      reinterpret_cast<const char *>(data), chars * sizeof *data, static_cast<int>(sizeof *data), *this);
 }
 
 template <Direction DIR>
 std::optional<char32_t> ExternalIoStatementState<DIR>::GetCurrentChar() {
   if constexpr (DIR == Direction::Output) {
     Crash(
         "ExternalIoStatementState<Direction::Output>::GetCurrentChar() called");
   }
int ExternalFormattedIoStatementState<DIR, CHAR>::EndIoStatement() {
   return ExternalIoStatementState<DIR>::EndIoStatement();
 }
 
 std::optional<DataEdit> IoStatementState::GetNextDataEdit(int n) {
   return std::visit(
       [&](auto &x) { return x.get().GetNextDataEdit(*this, n); }, u_);
 }
 
-bool IoStatementState::Emit(const char *data, std::size_t n) {
-  return std::visit([=](auto &x) { return x.get().Emit(data, n); }, u_);
+bool IoStatementState::Emit(
+    const char *data, std::size_t n, std::size_t elementBytes) {
+  return std::visit(
+      [=](auto &x) { return x.get().Emit(data, n, elementBytes); }, u_);
 }
 
 std::optional<char32_t> IoStatementState::GetCurrentChar() {
   return std::visit([&](auto &x) { return x.get().GetCurrentChar(); }, u_);
 }
 
 bool IoStatementState::AdvanceRecord(int n) {
   return std::visit([=](auto &x) { return x.get().AdvanceRecord(n); }, u_);
ListDirectedStatementState<Direction::Input>::GetNextDataEdit(
   if (!imaginaryPart_ && ch && *ch == '(') {
     realPart_ = true;
     io.HandleRelativePosition(1);
   }
   return edit;
 }
 
 template <Direction DIR>
-bool UnformattedIoStatementState<DIR>::Receive(char *data, std::size_t bytes) {
+bool UnformattedIoStatementState<DIR>::Receive(
+    char *data, std::size_t bytes, std::size_t elementBytes) {
   if constexpr (DIR == Direction::Output) {
     this->Crash(
         "UnformattedIoStatementState::Receive() called for output statement");
   }
-  return this->unit().Receive(data, bytes, *this);
+  return this->unit().Receive(data, bytes, elementBytes, *this);
+}
+
+template <Direction DIR>
+bool UnformattedIoStatementState<DIR>::Emit(
+    const char *data, std::size_t bytes, std::size_t elementBytes) {
+  if constexpr (DIR == Direction::Input) {
+    this->Crash(
+        "UnformattedIoStatementState::Emit() called for input statement");
+  }
+  return ExternalIoStatementState<DIR>::Emit(data, bytes, elementBytes);
 }
 
 template <Direction DIR>
 int UnformattedIoStatementState<DIR>::EndIoStatement() {
   ExternalFileUnit &unit{this->unit()};
   if constexpr (DIR == Direction::Output) {
     if (unit.access == Access::Sequential && !unit.isFixedRecordLength) {
       // Append the length of a sequential unformatted variable-length record

flang/runtime/main.h

 //===-- runtime/main.h ------------------------------------------*- 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 FORTRAN_RUNTIME_MAIN_H_
 #define FORTRAN_RUNTIME_MAIN_H_
 
 #include "c-or-cpp.h"
 #include "entry-names.h"
 
 FORTRAN_EXTERN_C_BEGIN
 void RTNAME(ProgramStart)(int, const char *[], const char *[]);
+void RTNAME(ByteswapOption)(); // -byteswapio
 FORTRAN_EXTERN_C_END
 
 #endif // FORTRAN_RUNTIME_MAIN_H_

flang/runtime/main.cpp

 
 extern "C" {
 void RTNAME(ProgramStart)(int argc, const char *argv[], const char *envp[]) {
   std::atexit(Fortran::runtime::NotifyOtherImagesOfNormalEnd);
   Fortran::runtime::executionEnvironment.Configure(argc, argv, envp);
   ConfigureFloatingPoint();
   // I/O is initialized on demand so that it works for non-Fortran main().
 }
+
+void RTNAME(ByteswapOption)() {
+  if (Fortran::runtime::executionEnvironment.conversion ==
+      Fortran::runtime::Convert::Unknown) {
+    // The environment variable overrides the command-line option;
+    // either of them take precedence over explicit OPEN(CONVERT=) specifiers.
+    Fortran::runtime::executionEnvironment.conversion =
+        Fortran::runtime::Convert::Swap;
+  }
+}
 }

flang/runtime/unit.h

static ExternalFileUnit &LookUpOrCreateAnonymous(
       int unit, Direction, bool isUnformatted, const Terminator &);
   static ExternalFileUnit &CreateNew(int unit, const Terminator &);
   static ExternalFileUnit *LookUpForClose(int unit);
   static int NewUnit(const Terminator &);
   static void CloseAll(IoErrorHandler &);
   static void FlushAll(IoErrorHandler &);
 
   void OpenUnit(OpenStatus, std::optional<Action>, Position,
-      OwningPtr<char> &&path, std::size_t pathLength, IoErrorHandler &);
+      OwningPtr<char> &&path, std::size_t pathLength, Convert,
+      IoErrorHandler &);
   void CloseUnit(CloseStatus, IoErrorHandler &);
   void DestroyClosed();
 
   bool SetDirection(Direction, IoErrorHandler &);
 
   template <typename A, typename... X>
   IoStatementState &BeginIoStatement(X &&... xs) {
     // TODO: Child data transfer statements vs. locking
     lock_.Take(); // dropped in EndIoStatement()
     A &state{u_.emplace<A>(std::forward<X>(xs)...)};
     if constexpr (!std::is_same_v<A, OpenStatementState>) {
       state.mutableModes() = ConnectionState::modes;
     }
     io_.emplace(state);
     return *io_;
   }
 
-  bool Emit(const char *, std::size_t, IoErrorHandler &);
-  bool Receive(char *, std::size_t, IoErrorHandler &);
+  bool Emit(
+      const char *, std::size_t, std::size_t elementBytes, IoErrorHandler &);
+  bool Receive(char *, std::size_t, std::size_t elementBytes, IoErrorHandler &);
   std::optional<char32_t> GetCurrentChar(IoErrorHandler &);
   void SetLeftTabLimit();
   void BeginReadingRecord(IoErrorHandler &);
   bool AdvanceRecord(IoErrorHandler &);
   void BackspaceRecord(IoErrorHandler &);
   void FlushIfTerminal(IoErrorHandler &);
   void Endfile(IoErrorHandler &);
   void Rewind(IoErrorHandler &);
private:
   std::optional<IoStatementState> io_;
 
   // Subtle: The beginning of the frame can't be allowed to advance
   // during a single list-directed READ due to the possibility of a
   // multi-record CHARACTER value with a "r*" repeat count.  So we
   // manage the frame and the current record therein separately.
   std::int64_t frameOffsetInFile_{0};
   std::size_t recordOffsetInFrame_{0}; // of currentRecordNumber
+
+  bool swapEndianness_{false};
 };
 
 } // namespace Fortran::runtime::io
 #endif // FORTRAN_RUNTIME_IO_UNIT_H_

flang/runtime/unit.cpp

 //===-- runtime/unit.cpp ----------------------------------------*- 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "unit.h"
+#include "environment.h"
 #include "io-error.h"
 #include "lock.h"
 #include "unit-map.h"
 #include <cstdio>
+#include <utility>
 
 namespace Fortran::runtime::io {
 
 // The per-unit data structures are created on demand so that Fortran I/O
 // should work without a Fortran main program.
 static Lock unitMapLock;
 static UnitMap *unitMap{nullptr};
 static ExternalFileUnit *defaultInput{nullptr};
if (!exists) {
     // I/O to an unconnected unit reads/creates a local file, e.g. fort.7
     std::size_t pathMaxLen{32};
     auto path{SizedNew<char>{terminator}(pathMaxLen)};
     std::snprintf(path.get(), pathMaxLen, "fort.%d", unit);
     IoErrorHandler handler{terminator};
     result.OpenUnit(
         dir == Direction::Input ? OpenStatus::Old : OpenStatus::Replace,
         Action::ReadWrite, Position::Rewind, std::move(path),
-        std::strlen(path.get()), handler);
+        std::strlen(path.get()), Convert::Native, handler);
     result.isUnformatted = isUnformatted;
   }
   return result;
 }
 
 ExternalFileUnit &ExternalFileUnit::CreateNew(
     int unit, const Terminator &terminator) {
   bool wasExtant{false};
   ExternalFileUnit &result{
       GetUnitMap().LookUpOrCreate(unit, terminator, wasExtant)};
   RUNTIME_CHECK(terminator, !wasExtant);
   return result;
 }
 
 ExternalFileUnit *ExternalFileUnit::LookUpForClose(int unit) {
   return GetUnitMap().LookUpForClose(unit);
 }
 
 int ExternalFileUnit::NewUnit(const Terminator &terminator) {
   return GetUnitMap().NewUnit(terminator).unitNumber();
 }
 
 void ExternalFileUnit::OpenUnit(OpenStatus status, std::optional<Action> action,
     Position position, OwningPtr<char> &&newPath, std::size_t newPathLength,
-    IoErrorHandler &handler) {
+    Convert convert, IoErrorHandler &handler) {
+  if (executionEnvironment.conversion != Convert::Unknown) {
+    convert = executionEnvironment.conversion;
+  }
+  swapEndianness_ = convert == Convert::Swap ||
+      (convert == Convert::LittleEndian && !isHostLittleEndian) ||
+      (convert == Convert::BigEndian && isHostLittleEndian);
   if (IsOpen()) {
     if (status == OpenStatus::Old &&
         (!newPath.get() ||
             (path() && pathLength() == newPathLength &&
                 std::memcmp(path(), newPath.get(), newPathLength) == 0))) {
       // OPEN of existing unit, STATUS='OLD', not new FILE=
       newPath.reset();
       return;

 
 void ExternalFileUnit::FlushAll(IoErrorHandler &handler) {
   CriticalSection critical{unitMapLock};
   if (unitMap) {
     unitMap->FlushAll(handler);
   }
 }
 
-bool ExternalFileUnit::Emit(
-    const char *data, std::size_t bytes, IoErrorHandler &handler) {
+static void SwapEndianness(
+    char *data, std::size_t bytes, std::size_t elementBytes) {
+  if (elementBytes > 1) {
+    auto half{elementBytes >> 1};
+    for (std::size_t j{0}; j + elementBytes <= bytes; j += elementBytes) {
+      for (std::size_t k{0}; k < half; ++k) {
+        std::swap(data[j + k], data[j + elementBytes - 1 - k]);
+      }
+    }
+  }
+}
+
+bool ExternalFileUnit::Emit(const char *data, std::size_t bytes,
+    std::size_t elementBytes, IoErrorHandler &handler) {
   auto furthestAfter{std::max(furthestPositionInRecord,
       positionInRecord + static_cast<std::int64_t>(bytes))};
   if (furthestAfter > recordLength.value_or(furthestAfter)) {
     handler.SignalError(IostatRecordWriteOverrun,
         "Attempt to write %zd bytes to position %jd in a fixed-size record of "
         "%jd bytes",
         bytes, static_cast<std::intmax_t>(positionInRecord),
         static_cast<std::intmax_t>(*recordLength));
     return false;
   }
   WriteFrame(frameOffsetInFile_, recordOffsetInFrame_ + furthestAfter, handler);
   if (positionInRecord > furthestPositionInRecord) {
     std::memset(Frame() + recordOffsetInFrame_ + furthestPositionInRecord, ' ',
         positionInRecord - furthestPositionInRecord);
   }
-  std::memcpy(Frame() + recordOffsetInFrame_ + positionInRecord, data, bytes);
+  char *to{Frame() + recordOffsetInFrame_ + positionInRecord};
+  std::memcpy(to, data, bytes);
+  if (swapEndianness_) {
+    SwapEndianness(to, bytes, elementBytes);
+  }
   positionInRecord += bytes;
   furthestPositionInRecord = furthestAfter;
   return true;
 }
 
-bool ExternalFileUnit::Receive(
-    char *data, std::size_t bytes, IoErrorHandler &handler) {
+bool ExternalFileUnit::Receive(char *data, std::size_t bytes,
+    std::size_t elementBytes, IoErrorHandler &handler) {
   RUNTIME_CHECK(handler, direction_ == Direction::Input);
   auto furthestAfter{std::max(furthestPositionInRecord,
       positionInRecord + static_cast<std::int64_t>(bytes))};
   if (furthestAfter > recordLength.value_or(furthestAfter)) {
     handler.SignalError(IostatRecordReadOverrun,
         "Attempt to read %zd bytes at position %jd in a record of %jd bytes",
         bytes, static_cast<std::intmax_t>(positionInRecord),
         static_cast<std::intmax_t>(*recordLength));
     return false;
   }
   auto need{recordOffsetInFrame_ + furthestAfter};
   auto got{ReadFrame(frameOffsetInFile_, need, handler)};
   if (got >= need) {
     std::memcpy(data, Frame() + recordOffsetInFrame_ + positionInRecord, bytes);
+    if (swapEndianness_) {
+      SwapEndianness(data, bytes, elementBytes);
+    }
     positionInRecord += bytes;
     furthestPositionInRecord = furthestAfter;
     return true;
   } else {
     handler.SignalEnd();
     endfileRecordNumber = currentRecordNumber;
     return false;
   }
if (!isUnformatted) {
       if (isFixedRecordLength && recordLength) {
         if (furthestPositionInRecord < *recordLength) {
           WriteFrame(frameOffsetInFile_, *recordLength, handler);
           std::memset(Frame() + recordOffsetInFrame_ + furthestPositionInRecord,
               ' ', *recordLength - furthestPositionInRecord);
         }
       } else {
         positionInRecord = furthestPositionInRecord;
-        ok &= Emit("\n", 1, handler); // TODO: Windows CR+LF
+        ok &= Emit("\n", 1, 1, handler); // TODO: Windows CR+LF
       }
     }
     frameOffsetInFile_ +=
         recordOffsetInFrame_ + recordLength.value_or(furthestPositionInRecord);
     recordOffsetInFrame_ = 0;
     impliedEndfile_ = true;
   }
   ++currentRecordNumber;

flang/tools/f18/f18.cpp

struct DriverOptions {
   bool compileOnly{false}; // -c
   std::string outputPath; // -o path
   std::vector<std::string> searchDirectories{"."s}; // -I dir
   std::string moduleDirectory{"."s}; // -module dir
   std::string moduleFileSuffix{".mod"}; // -moduleSuffix suff
   bool forcedForm{false}; // -Mfixed or -Mfree appeared
   bool warnOnNonstandardUsage{false}; // -Mstandard
   bool warningsAreErrors{false}; // -Werror
+  bool byteswapio{false}; // -byteswapio
   Fortran::parser::Encoding encoding{Fortran::parser::Encoding::UTF_8};
   bool parseOnly{false};
   bool dumpProvenance{false};
   bool dumpCookedChars{false};
   bool dumpUnparse{false};
   bool dumpUnparseWithSymbols{false};
   bool dumpParseTree{false};
   bool dumpPreFirTree{false};
if (arg.empty()) {
                        << args.front() << '\n';
           return EXIT_FAILURE;
         }
         args.pop_front();
       }
       driver.getDefinitionArgs = {arguments[0], arguments[1], arguments[2]};
     } else if (arg == "-fget-symbols-sources") {
       driver.getSymbolsSources = true;
+    } else if (arg == "-byteswapio") {
+      driver.byteswapio = true; // TODO: Pass to lowering, generate call
     } else if (arg == "-help" || arg == "--help" || arg == "-?") {
       llvm::errs()
           << "f18 options:\n"
           << "  -Mfixed | -Mfree | -ffixed-form | -ffree-form   force the "
              "source form\n"
           << "  -Mextend | -ffixed-line-length-132   132-column fixed form\n"
           << "  -f[no-]backslash     enable[disable] \\escapes in literals\n"
           << "  -M[no]backslash      disable[enable] \\escapes in literals\n"

flang/unittests/Runtime/external-io.cpp

void TestDirectUnformatted() {
   (io) == IostatOk || (Fail() << "EndIoStatement() for OpenNewUnit", 0);
   static constexpr int records{10};
   for (int j{1}; j <= records; ++j) {
     // WRITE(UNIT=unit,REC=j) j
     io = IONAME(BeginUnformattedOutput)(unit, __FILE__, __LINE__);
     IONAME(SetRec)(io, j) || (Fail() << "SetRec(" << j << ')', 0);
     buffer = j;
     IONAME(OutputUnformattedBlock)
-    (io, reinterpret_cast<const char *>(&buffer), recl) ||
+    (io, reinterpret_cast<const char *>(&buffer), recl, recl) ||
         (Fail() << "OutputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for OutputUnformattedBlock", 0);
   }
   for (int j{records}; j >= 1; --j) {
     // READ(UNIT=unit,REC=j) n
     io = IONAME(BeginUnformattedInput)(unit, __FILE__, __LINE__);
     IONAME(SetRec)
     (io, j) || (Fail() << "SetRec(" << j << ')', 0);
     IONAME(InputUnformattedBlock)
-    (io, reinterpret_cast<char *>(&buffer), recl) ||
+    (io, reinterpret_cast<char *>(&buffer), recl, recl) ||
         (Fail() << "InputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for InputUnformattedBlock", 0);
     if (buffer != j) {
       Fail() << "Read back " << buffer << " from direct unformatted record "
              << j << ", expected " << j << '\n';
     }
   }
   // CLOSE(UNIT=unit,STATUS='DELETE')
   io = IONAME(BeginClose)(unit, __FILE__, __LINE__);
   IONAME(SetStatus)(io, "DELETE", 6) || (Fail() << "SetStatus(DELETE)", 0);
   IONAME(EndIoStatement)
   (io) == IostatOk || (Fail() << "EndIoStatement() for Close", 0);
   llvm::errs() << "end TestDirectUnformatted()\n";
 }
 
+void TestDirectUnformattedSwapped() {
+  llvm::errs() << "begin TestDirectUnformattedSwapped()\n";
+  // OPEN(NEWUNIT=unit,ACCESS='DIRECT',ACTION='READWRITE',&
+  //   FORM='UNFORMATTED',RECL=8,STATUS='SCRATCH',CONVERT='NATIVE')
+  auto io{IONAME(BeginOpenNewUnit)(__FILE__, __LINE__)};
+  IONAME(SetAccess)(io, "DIRECT", 6) || (Fail() << "SetAccess(DIRECT)", 0);
+  IONAME(SetAction)
+  (io, "READWRITE", 9) || (Fail() << "SetAction(READWRITE)", 0);
+  IONAME(SetForm)
+  (io, "UNFORMATTED", 11) || (Fail() << "SetForm(UNFORMATTED)", 0);
+  IONAME(SetConvert)
+  (io, "NATIVE", 6) || (Fail() << "SetConvert(NATIVE)", 0);
+  std::int64_t buffer;
+  static constexpr std::size_t recl{sizeof buffer};
+  IONAME(SetRecl)(io, recl) || (Fail() << "SetRecl()", 0);
+  IONAME(SetStatus)(io, "SCRATCH", 7) || (Fail() << "SetStatus(SCRATCH)", 0);
+  int unit{-1};
+  IONAME(GetNewUnit)(io, unit) || (Fail() << "GetNewUnit()", 0);
+  llvm::errs() << "unit=" << unit << '\n';
+  IONAME(EndIoStatement)
+  (io) == IostatOk || (Fail() << "EndIoStatement() for OpenNewUnit", 0);
+  static constexpr int records{10};
+  for (int j{1}; j <= records; ++j) {
+    // WRITE(UNIT=unit,REC=j) j
+    io = IONAME(BeginUnformattedOutput)(unit, __FILE__, __LINE__);
+    IONAME(SetRec)(io, j) || (Fail() << "SetRec(" << j << ')', 0);
+    buffer = j;
+    IONAME(OutputUnformattedBlock)
+    (io, reinterpret_cast<const char *>(&buffer), recl, recl) ||
+        (Fail() << "OutputUnformattedBlock()", 0);
+    IONAME(EndIoStatement)
+    (io) == IostatOk ||
+        (Fail() << "EndIoStatement() for OutputUnformattedBlock", 0);
+  }
+  // OPEN(UNIT=unit,STATUS='OLD',CONVERT='SWAP')
+  io = IONAME(BeginOpenUnit)(unit, __FILE__, __LINE__);
+  IONAME(SetStatus)(io, "OLD", 3) || (Fail() << "SetStatus(OLD)", 0);
+  IONAME(SetConvert)
+  (io, "SWAP", 4) || (Fail() << "SetConvert(SWAP)", 0);
+  IONAME(EndIoStatement)
+  (io) == IostatOk || (Fail() << "EndIoStatement() for OpenUnit", 0);
+  for (int j{records}; j >= 1; --j) {
+    // READ(UNIT=unit,REC=j) n
+    io = IONAME(BeginUnformattedInput)(unit, __FILE__, __LINE__);
+    IONAME(SetRec)
+    (io, j) || (Fail() << "SetRec(" << j << ')', 0);
+    IONAME(InputUnformattedBlock)
+    (io, reinterpret_cast<char *>(&buffer), recl, recl) ||
+        (Fail() << "InputUnformattedBlock()", 0);
+    IONAME(EndIoStatement)
+    (io) == IostatOk ||
+        (Fail() << "EndIoStatement() for InputUnformattedBlock", 0);
+    if (buffer >> 56 != j) {
+      Fail() << "Read back " << (buffer >> 56)
+             << " from direct unformatted record " << j << ", expected " << j
+             << '\n';
+    }
+  }
+  // CLOSE(UNIT=unit,STATUS='DELETE')
+  io = IONAME(BeginClose)(unit, __FILE__, __LINE__);
+  IONAME(SetStatus)(io, "DELETE", 6) || (Fail() << "SetStatus(DELETE)", 0);
+  IONAME(EndIoStatement)
+  (io) == IostatOk || (Fail() << "EndIoStatement() for Close", 0);
+  llvm::errs() << "end TestDirectUnformatted()\n";
+}
+
 void TestSequentialFixedUnformatted() {
   llvm::errs() << "begin TestSequentialFixedUnformatted()\n";
   // OPEN(NEWUNIT=unit,ACCESS='SEQUENTIAL',ACTION='READWRITE',&
   //   FORM='UNFORMATTED',RECL=8,STATUS='SCRATCH')
   auto io{IONAME(BeginOpenNewUnit)(__FILE__, __LINE__)};
   IONAME(SetAccess)
       (io, "SEQUENTIAL", 10) || (Fail() << "SetAccess(SEQUENTIAL)", 0);
   IONAME(SetAction)
void TestSequentialFixedUnformatted() {
   IONAME(EndIoStatement)
   (io) == IostatOk || (Fail() << "EndIoStatement() for OpenNewUnit", 0);
   static const int records{10};
   for (int j{1}; j <= records; ++j) {
     // DO J=1,RECORDS; WRITE(UNIT=unit) j; END DO
     io = IONAME(BeginUnformattedOutput)(unit, __FILE__, __LINE__);
     buffer = j;
     IONAME(OutputUnformattedBlock)
-    (io, reinterpret_cast<const char *>(&buffer), recl) ||
+    (io, reinterpret_cast<const char *>(&buffer), recl, recl) ||
         (Fail() << "OutputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for OutputUnformattedBlock", 0);
   }
   // REWIND(UNIT=unit)
   io = IONAME(BeginRewind)(unit, __FILE__, __LINE__);
   IONAME(EndIoStatement)
   (io) == IostatOk || (Fail() << "EndIoStatement() for Rewind", 0);
   for (int j{1}; j <= records; ++j) {
     // DO J=1,RECORDS; READ(UNIT=unit) n; check n; END DO
     io = IONAME(BeginUnformattedInput)(unit, __FILE__, __LINE__);
     IONAME(InputUnformattedBlock)
-    (io, reinterpret_cast<char *>(&buffer), recl) ||
+    (io, reinterpret_cast<char *>(&buffer), recl, recl) ||
         (Fail() << "InputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for InputUnformattedBlock", 0);
     if (buffer != j) {
       Fail() << "Read back " << buffer
              << " from sequential fixed unformatted record " << j
              << ", expected " << j << '\n';
     }
   }
   for (int j{records}; j >= 1; --j) {
     // BACKSPACE(UNIT=unit)
     io = IONAME(BeginBackspace)(unit, __FILE__, __LINE__);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for Backspace (before read)", 0);
     // READ(UNIT=unit) n
     io = IONAME(BeginUnformattedInput)(unit, __FILE__, __LINE__);
     IONAME(InputUnformattedBlock)
-    (io, reinterpret_cast<char *>(&buffer), recl) ||
+    (io, reinterpret_cast<char *>(&buffer), recl, recl) ||
         (Fail() << "InputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for InputUnformattedBlock", 0);
     if (buffer != j) {
       Fail() << "Read back " << buffer
              << " from sequential fixed unformatted record " << j
              << " after backspacing, expected " << j << '\n';
void TestSequentialVariableUnformatted() {
   std::int64_t buffer[records]; // INTEGER*8 :: BUFFER(0:9) = [(j,j=0,9)]
   for (int j{0}; j < records; ++j) {
     buffer[j] = j;
   }
   for (int j{1}; j <= records; ++j) {
     // DO J=1,RECORDS; WRITE(UNIT=unit) BUFFER(0:j); END DO
     io = IONAME(BeginUnformattedOutput)(unit, __FILE__, __LINE__);
     IONAME(OutputUnformattedBlock)
-    (io, reinterpret_cast<const char *>(&buffer), j * sizeof *buffer) ||
+    (io, reinterpret_cast<const char *>(&buffer), j * sizeof *buffer,
+        sizeof *buffer) ||
         (Fail() << "OutputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for OutputUnformattedBlock", 0);
   }
   // REWIND(UNIT=unit)
   io = IONAME(BeginRewind)(unit, __FILE__, __LINE__);
   IONAME(EndIoStatement)
   (io) == IostatOk || (Fail() << "EndIoStatement() for Rewind", 0);
   for (int j{1}; j <= records; ++j) {
     // DO J=1,RECORDS; READ(UNIT=unit) n; check n; END DO
     io = IONAME(BeginUnformattedInput)(unit, __FILE__, __LINE__);
     IONAME(InputUnformattedBlock)
-    (io, reinterpret_cast<char *>(&buffer), j * sizeof *buffer) ||
+    (io, reinterpret_cast<char *>(&buffer), j * sizeof *buffer,
+        sizeof *buffer) ||
         (Fail() << "InputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for InputUnformattedBlock", 0);
     for (int k{0}; k < j; ++k) {
       if (buffer[k] != k) {
         Fail() << "Read back [" << k << "]=" << buffer[k]
                << " from direct unformatted record " << j << ", expected " << k
                << '\n';
       }
     }
   }
   for (int j{records}; j >= 1; --j) {
     // BACKSPACE(unit)
     io = IONAME(BeginBackspace)(unit, __FILE__, __LINE__);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for Backspace (before read)", 0);
     // READ(unit=unit) n; check
     io = IONAME(BeginUnformattedInput)(unit, __FILE__, __LINE__);
     IONAME(InputUnformattedBlock)
-    (io, reinterpret_cast<char *>(&buffer), j * sizeof *buffer) ||
+    (io, reinterpret_cast<char *>(&buffer), j * sizeof *buffer,
+        sizeof *buffer) ||
         (Fail() << "InputUnformattedBlock()", 0);
     IONAME(EndIoStatement)
     (io) == IostatOk ||
         (Fail() << "EndIoStatement() for InputUnformattedBlock", 0);
     for (int k{0}; k < j; ++k) {
       if (buffer[k] != k) {
         Fail() << "Read back [" << k << "]=" << buffer[k]
                << " from sequential variable unformatted record " << j

 
 void TestStreamUnformatted() {
   // TODO
 }
 
 int main() {
   StartTests();
   TestDirectUnformatted();
+  TestDirectUnformattedSwapped();
   TestSequentialFixedUnformatted();
   TestSequentialVariableUnformatted();
   TestDirectFormatted();
   TestSequentialVariableFormatted();
   TestStreamUnformatted();
   return EndTests();
 }