source: Daodan/MSYS2/mingw32/lib/gcc/i686-w64-mingw32/11.2.0/include/mm_malloc.h

/* Copyright (C) 2004-2021 Free Software Foundation, Inc.

   This file is part of GCC.

   GCC 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, or (at your option)
   any later version.

   GCC 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.

   Under Section 7 of GPL version 3, you are granted additional
   permissions described in the GCC Runtime Library Exception, version
   3.1, as published by the Free Software Foundation.

   You should have received a copy of the GNU General Public License and
   a copy of the GCC Runtime Library Exception along with this program;
   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _MM_MALLOC_H_INCLUDED
#define _MM_MALLOC_H_INCLUDED

#include <stdlib.h>
#if __STDC_HOSTED__
#include <errno.h>
#endif

static __inline__ void * 
_mm_malloc (size_t __size, size_t __align)
{
  void * __malloc_ptr;
  void * __aligned_ptr;

  /* Error if align is not a power of two.  */
  if (__align & (__align - 1))
    {
#if __STDC_HOSTED__
      errno = EINVAL;
#endif
      return ((void *) 0);
    }

  if (__size == 0)
    return ((void *) 0);

 /* Assume malloc'd pointer is aligned at least to sizeof (void*).
    If necessary, add another sizeof (void*) to store the value
    returned by malloc. Effectively this enforces a minimum alignment
    of sizeof double. */     
    if (__align < 2 * sizeof (void *))
      __align = 2 * sizeof (void *);

  __malloc_ptr = malloc (__size + __align);
  if (!__malloc_ptr)
    return ((void *) 0);

  /* Align  We have at least sizeof (void *) space below malloc'd ptr. */
  __aligned_ptr = (void *) (((size_t) __malloc_ptr + __align)
                            & ~((size_t) (__align) - 1));

  /* Store the original pointer just before p.  */      
  ((void **) __aligned_ptr)[-1] = __malloc_ptr;

  return __aligned_ptr;
}

static __inline__ void
_mm_free (void *__aligned_ptr)
{
  if (__aligned_ptr)
    free (((void **) __aligned_ptr)[-1]);
}

#endif /* _MM_MALLOC_H_INCLUDED */