byte-swap.h

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1996-2025 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
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////////////////////////////////////////////////////////////////////////
 
#if ! defined (octave_byte_swap_h)
#define octave_byte_swap_h 1
 
#include "octave-config.h"
 
static inline void
swap_bytes (void *ptr, unsigned int i, unsigned int j)
{
  char *t = static_cast<char *> (ptr);
 
  char tmp = t[i];
  t[i] = t[j];
  t[j] = tmp;
}
 
template <int n>
void
swap_bytes (void *ptr)
{
  for (int i = 0; i < n/2; i++)
    swap_bytes (ptr, i, n-1-i);
}
 
template <>
inline void
swap_bytes<1> (void *)
{ }
 
template <>
inline void
swap_bytes<2> (void *ptr)
{
  swap_bytes (ptr, 0, 1);
}
 
template <>
inline void
swap_bytes<4> (void *ptr)
{
  swap_bytes (ptr, 0, 3);
  swap_bytes (ptr, 1, 2);
}
 
template <>
inline void
swap_bytes<8> (void *ptr)
{
  swap_bytes (ptr, 0, 7);
  swap_bytes (ptr, 1, 6);
  swap_bytes (ptr, 2, 5);
  swap_bytes (ptr, 3, 4);
}
 
template <int n>
void
swap_bytes (void *ptr, int len)
{
  char *t = static_cast<char *> (ptr);
 
  for (int i = 0; i < len; i++)
    {
      swap_bytes<n> (t);
      t += n;
    }
}
 
template <>
inline void
swap_bytes<1> (void *, int)
{ }
 
#endif