oct-mem.h

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/*

Copyright (C) 2009-2012 VZLU Prague

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
<http://www.gnu.org/licenses/>.

*/

#if !defined (octave_memory_h)
#define octave_memory_h 1

#include <cstddef>
#include <cstring>
#include <algorithm>

#include "oct-cmplx.h"
#include "oct-inttypes.h"

// NOTE: These functions are used to optimize stuff where performance is a
// priority. They assume that the std::complex and octave_int can be
// manipulated as plain memory, an assumption that is always true in practice
// but not theoretically guaranteed by the C++ standard. In the future, C++ may
// provide a better way to accomplish these tasks.

inline size_t safe_size_comp (size_t n, size_t size)
{
  if (n > static_cast<size_t> (-1) / size)
    throw std::bad_alloc ();
  return n * size;
}

// Unaliased copy. This boils down to memcpy, even for octave_int and complex types.

template <class T>
inline void copy_or_memcpy (size_t n, const T *src, T *dest)
{ std::copy (src, src + n, dest); }

#define DEFINE_POD_UCOPY(T) \
inline void copy_or_memcpy (size_t n, const T *src, T *dest) \
{ std::memcpy (dest, src, n * sizeof (T)); }

DEFINE_POD_UCOPY (double)
DEFINE_POD_UCOPY (float)
DEFINE_POD_UCOPY (char)
DEFINE_POD_UCOPY (short)
DEFINE_POD_UCOPY (int)
DEFINE_POD_UCOPY (long)
DEFINE_POD_UCOPY (unsigned char)
DEFINE_POD_UCOPY (unsigned short)
DEFINE_POD_UCOPY (unsigned int)
DEFINE_POD_UCOPY (unsigned long)

DEFINE_POD_UCOPY (Complex)
DEFINE_POD_UCOPY (FloatComplex)

template <class T>
DEFINE_POD_UCOPY (octave_int<T>)

// Fill by value, with a check for zero. This boils down to memset if value is
// a POD zero.
template <class T>
inline void fill_or_memset (size_t n, const T& value, T *dest)
{ std::fill_n (dest, n, value); }

template <class T>
inline bool helper_is_zero_mem (const T& value)
{
  typedef typename query_integer_type<sizeof (T), false>::type IT; // get integer type of the same size.
  return *(reinterpret_cast<const IT *>(&value)) == 0;
}

template <class T>
inline bool helper_is_zero_mem (const std::complex<T>& value)
{
  return (helper_is_zero_mem (value.real ())
          && helper_is_zero_mem (value.imag ()));
}

template <class T>
inline bool helper_is_zero_mem (const octave_int<T>& value)
{ return value.value () == T(); }

#define DEFINE_POD_FILL(T) \
inline void fill_or_memset (size_t n, const T& value, T *dest) \
{ \
  if (helper_is_zero_mem (value)) \
    std::memset (dest, 0, n * sizeof (T)); \
  else \
    std::fill_n (dest, n, value); \
}

DEFINE_POD_FILL (double)
DEFINE_POD_FILL (float)
DEFINE_POD_FILL (char)
DEFINE_POD_FILL (short)
DEFINE_POD_FILL (int)
DEFINE_POD_FILL (long)
DEFINE_POD_FILL (unsigned char)
DEFINE_POD_FILL (unsigned short)
DEFINE_POD_FILL (unsigned int)
DEFINE_POD_FILL (unsigned long)

DEFINE_POD_FILL (Complex)
DEFINE_POD_FILL (FloatComplex)

template <class T>
DEFINE_POD_FILL (octave_int<T>)

// Uninitialized allocation. Will not initialize memory for complex and octave_int.
// Memory allocated by octave_new should be freed by octave_delete.
template <class T>
inline T *no_ctor_new (size_t n)
{
  // Some systems let us allocate > 2GB memory even though size_t, which is either
  // buggy or completely cuckoo, so let's check here to stay safe.
  safe_size_comp (n, sizeof (T));
  return new T[n];
}
template <class T>
inline void no_ctor_delete (T *ptr)
{ delete [] ptr; }

#define DEFINE_POD_NEW_DELETE(T) \
template <> \
inline T *no_ctor_new<T > (size_t n) \
{ return reinterpret_cast<T *> (new char[safe_size_comp (n, sizeof (T))]); } \
template <> \
inline void no_ctor_delete<T > (T *ptr) \
{ delete [] reinterpret_cast<char *> (ptr); }

DEFINE_POD_NEW_DELETE (Complex)
DEFINE_POD_NEW_DELETE (FloatComplex)

DEFINE_POD_NEW_DELETE (octave_int8)
DEFINE_POD_NEW_DELETE (octave_int16)
DEFINE_POD_NEW_DELETE (octave_int32)
DEFINE_POD_NEW_DELETE (octave_int64)
DEFINE_POD_NEW_DELETE (octave_uint8)
DEFINE_POD_NEW_DELETE (octave_uint16)
DEFINE_POD_NEW_DELETE (octave_uint32)
DEFINE_POD_NEW_DELETE (octave_uint64)

#endif /* octave_memory_h */