LittleEndianConversion.h

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// # LittleEndianConversion.h: A class with static functions to convert littleEndian format
// # Copyright (C) 1996,1997,1999,2001
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 of the License, or (at your
// # option) any later version.
// #
// # This library is distributed in the hope that it will be useful, but WITHOUT
// # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef CASA_LITTLEENDIANCONVERSION_H
#define CASA_LITTLEENDIANCONVERSION_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/OS/CanonicalConversion.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// A class with static functions to convert littleEndian format
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="Friso Olnon" date="1996/11/06" tests="tVAXConversion" demos="">
// </reviewed>
 
// <synopsis>
// This class is intended to be used as a common class for all
// classes converting data to/from little-endian format.
// </synopsis>
 
// <motivation>
// Sometimes data are stored in little-endian format (e.g. old VAX-data).
// Instead of putting all these conversion functions in all such classes,
// it is better to keep them separate to be able to use them elsewhere.
// However, note that this version handles a long as 4 bytes.
// On several little-endian machines (e.g. DEC-alpha) a long is 8 bytes,
// so a special function is needed for them.
// </motivation>
 
// <todo asof="$DATE$">
//  <li> Support data type long double.
//  <li> Support a long as 4 or as 8 bytes.
// </todo>
 
class LittleEndianConversion {
 public:
  // Convert one value from littleEndian format to local format.
  // The from and to buffer should not overlap.
  // <group>
  static void toLocal(char& to, const void* from);
  static void toLocal(unsigned char& to, const void* from);
  static void toLocal(short& to, const void* from);
  static void toLocal(unsigned short& to, const void* from);
  static void toLocal(int& to, const void* from);
  static void toLocal(unsigned int& to, const void* from);
  static void toLocal(Int64& to, const void* from);
  static void toLocal(uInt64& to, const void* from);
  static void toLocal(float& to, const void* from);
  static void toLocal(double& to, const void* from);
  // </group>
 
  // Convert nr values from littleEndian format to local format.
  // The from and to buffer should not overlap.
  // <group>
  static void toLocal(char* to, const void* from, size_t nr);
  static void toLocal(unsigned char* to, const void* from, size_t nr);
  static void toLocal(short* to, const void* from, size_t nr);
  static void toLocal(unsigned short* to, const void* from, size_t nr);
  static void toLocal(int* to, const void* from, size_t nr);
  static void toLocal(unsigned int* to, const void* from, size_t nr);
  static void toLocal(Int64* to, const void* from, size_t nr);
  static void toLocal(uInt64* to, const void* from, size_t nr);
  static void toLocal(float* to, const void* from, size_t nr);
  static void toLocal(double* to, const void* from, size_t nr);
  // </group>
 
  // Convert one value from local format to littleEndian format.
  // The from and to buffer should not overlap.
  // <group>
  static void fromLocal(void* to, char from);
  static void fromLocal(void* to, unsigned char from);
  static void fromLocal(void* to, short from);
  static void fromLocal(void* to, unsigned short from);
  static void fromLocal(void* to, int from);
  static void fromLocal(void* to, unsigned int from);
  static void fromLocal(void* to, Int64 from);
  static void fromLocal(void* to, uInt64 from);
  static void fromLocal(void* to, float from);
  static void fromLocal(void* to, double from);
  // </group>
 
  // Convert nr values from local format to littleEndian format.
  // The from and to buffer should not overlap.
  // <group>
  static void fromLocal(void* to, const char* from, size_t nr);
  static void fromLocal(void* to, const unsigned char* from, size_t nr);
  static void fromLocal(void* to, const short* from, size_t nr);
  static void fromLocal(void* to, const unsigned short* from, size_t nr);
  static void fromLocal(void* to, const int* from, size_t nr);
  static void fromLocal(void* to, const unsigned int* from, size_t nr);
  static void fromLocal(void* to, const Int64* from, size_t nr);
  static void fromLocal(void* to, const uInt64* from, size_t nr);
  static void fromLocal(void* to, const float* from, size_t nr);
  static void fromLocal(void* to, const double* from, size_t nr);
  // </group>
 
 private:
  // This class should not be constructed
  // (so declare the constructor private).
  LittleEndianConversion();
};
 
inline void LittleEndianConversion::toLocal(char& to, const void* from) { to = *(char*)from; }
 
inline void LittleEndianConversion::toLocal(unsigned char& to, const void* from) {
  to = *(unsigned char*)from;
}
 
inline void LittleEndianConversion::toLocal(short& to, const void* from) {
  if (sizeof(short) != 2) {
    if (((signed char*)from)[2] < 0) {
      to = -1;
    } else {
      to = 0;
    }
  }
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse2(((char*)&to) + sizeof(short) - 2, from);
#else
  CanonicalConversion::move2(&to, from);
#endif
}
 
inline void LittleEndianConversion::toLocal(unsigned short& to, const void* from) {
  if (sizeof(unsigned short) != 2) {
    to = 0;
  }
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse2(((char*)&to) + sizeof(unsigned short) - 2, from);
#else
  CanonicalConversion::move2(&to, from);
#endif
}
 
inline void LittleEndianConversion::toLocal(int& to, const void* from) {
  if (sizeof(int) != 4) {
    if (((signed char*)from)[3] < 0) {
      to = -1;
    } else {
      to = 0;
    }
  }
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(((char*)&to) + sizeof(int) - 4, from);
#else
  CanonicalConversion::move4(&to, from);
#endif
}
 
inline void LittleEndianConversion::toLocal(unsigned int& to, const void* from) {
  if (sizeof(unsigned int) != 4) {
    to = 0;
  }
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(((char*)&to) + sizeof(unsigned int) - 4, from);
#else
  CanonicalConversion::move4(&to, from);
#endif
}
 
inline void LittleEndianConversion::toLocal(Int64& to, const void* from) {
  int tmp;
  LittleEndianConversion::toLocal(tmp, from);
  to = tmp;
}
 
inline void LittleEndianConversion::toLocal(uInt64& to, const void* from) {
  unsigned int tmp;
  LittleEndianConversion::toLocal(tmp, from);
  to = tmp;
}
 
inline void LittleEndianConversion::toLocal(float& to, const void* from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(&to, from);
#else
  CanonicalConversion::move4(&to, from);
#endif
}
 
inline void LittleEndianConversion::toLocal(double& to, const void* from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse8(&to, from);
#else
  CanonicalConversion::move8(&to, from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, char from) { *(char*)to = from; }
inline void LittleEndianConversion::fromLocal(void* to, unsigned char from) {
  *(unsigned char*)to = from;
}
 
inline void LittleEndianConversion::fromLocal(void* to, short from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse2(to, ((char*)&from) + sizeof(short) - 2);
#else
  CanonicalConversion::move2(to, &from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, unsigned short from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse2(to, ((char*)&from) + sizeof(unsigned short) - 2);
#else
  CanonicalConversion::move2(to, &from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, int from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(to, ((char*)&from) + sizeof(int) - 4);
#else
  CanonicalConversion::move4(to, &from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, unsigned int from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(to, ((char*)&from) + sizeof(unsigned int) - 4);
#else
  CanonicalConversion::move4(to, &from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, Int64 from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(to, ((char*)&from) + sizeof(Int64) - 4);
#else
  CanonicalConversion::move4(to, &from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, uInt64 from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(to, ((char*)&from) + sizeof(uInt64) - 4);
#else
  CanonicalConversion::move4(to, &from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, float from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse4(to, ((char*)&from) + sizeof(float) - 4);
#else
  CanonicalConversion::move4(to, &from);
#endif
}
 
inline void LittleEndianConversion::fromLocal(void* to, double from) {
#if !defined(AIPS_LITTLE_ENDIAN)
  CanonicalConversion::reverse8(to, ((char*)&from) + sizeof(double) - 8);
#else
  CanonicalConversion::move8(to, &from);
#endif
}
 
}  // namespace casacore
 
#endif