text: //===- SwapByteOrder.h - Generic and optimized byte swaps -------*- 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
  //
  //===----------------------------------------------------------------------===//
  //
  // This file declares generic and optimized functions to swap the byte order of
  // an integral type.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_SUPPORT_SWAPBYTEORDER_H
  #define LLVM_SUPPORT_SWAPBYTEORDER_H
  
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/DataTypes.h"
  #include <cstddef>
  #if defined(_MSC_VER) && !defined(_DEBUG)
  #include <stdlib.h>
  #endif
  
  namespace llvm {
  namespace sys {
  
  /// SwapByteOrder_16 - This function returns a byte-swapped representation of
  /// the 16-bit argument.
  inline uint16_t SwapByteOrder_16(uint16_t value) {
  #if defined(_MSC_VER) && !defined(_DEBUG)
    // The DLL version of the runtime lacks these functions (bug!?), but in a
    // release build they're replaced with BSWAP instructions anyway.
    return _byteswap_ushort(value);
  #else
    uint16_t Hi = value << 8;
    uint16_t Lo = value >> 8;
    return Hi | Lo;
  #endif
  }
  
  /// SwapByteOrder_32 - This function returns a byte-swapped representation of
  /// the 32-bit argument.
  inline uint32_t SwapByteOrder_32(uint32_t value) {
  #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC))
    return __builtin_bswap32(value);
  #elif defined(_MSC_VER) && !defined(_DEBUG)
    return _byteswap_ulong(value);
  #else
    uint32_t Byte0 = value & 0x000000FF;
    uint32_t Byte1 = value & 0x0000FF00;
    uint32_t Byte2 = value & 0x00FF0000;
    uint32_t Byte3 = value & 0xFF000000;
    return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
  #endif
  }
  
  /// SwapByteOrder_64 - This function returns a byte-swapped representation of
  /// the 64-bit argument.
  inline uint64_t SwapByteOrder_64(uint64_t value) {
  #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC))
    return __builtin_bswap64(value);
  #elif defined(_MSC_VER) && !defined(_DEBUG)
    return _byteswap_uint64(value);
  #else
    uint64_t Hi = SwapByteOrder_32(uint32_t(value));
    uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32));
    return (Hi << 32) | Lo;
  #endif
  }
  
  inline unsigned char  getSwappedBytes(unsigned char C) { return C; }
  inline   signed char  getSwappedBytes(signed char C) { return C; }
  inline          char  getSwappedBytes(char C) { return C; }
  
  inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
  inline   signed short getSwappedBytes(  signed short C) { return SwapByteOrder_16(C); }
  
  inline unsigned int   getSwappedBytes(unsigned int   C) { return SwapByteOrder_32(C); }
  inline   signed int   getSwappedBytes(  signed int   C) { return SwapByteOrder_32(C); }
  
  #if __LONG_MAX__ == __INT_MAX__
  inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_32(C); }
  inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_32(C); }
  #elif __LONG_MAX__ == __LONG_LONG_MAX__
  inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_64(C); }
  inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_64(C); }
  #else
  #error "Unknown long size!"
  #endif
  
  inline unsigned long long getSwappedBytes(unsigned long long C) {
    return SwapByteOrder_64(C);
  }
  inline signed long long getSwappedBytes(signed long long C) {
    return SwapByteOrder_64(C);
  }
  
  inline float getSwappedBytes(float C) {
    union {
      uint32_t i;
      float f;
    } in, out;
    in.f = C;
    out.i = SwapByteOrder_32(in.i);
    return out.f;
  }
  
  inline double getSwappedBytes(double C) {
    union {
      uint64_t i;
      double d;
    } in, out;
    in.d = C;
    out.i = SwapByteOrder_64(in.i);
    return out.d;
  }
  
  template<typename T>
  inline void swapByteOrder(T &Value) {
    Value = getSwappedBytes(Value);
  }
  
  } // end namespace sys
  } // end namespace llvm
  
  #endif