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/*
__mingw_aligned_malloc and friends, implemented using Microsoft's public
interfaces and with the help of the algorithm description provided
by Wu Yongwei: http://sourceforge.net/mailarchive/message.php?msg_id=3847075
I hereby place this implementation in the public domain.
-- Steven G. Johnson (stevenj@alum.mit.edu)
*/
#include <stdlib.h>
#include <errno.h>
#include <stddef.h> /* ptrdiff_t */
#include <string.h> /* memmove */
#ifdef HAVE_STDINT_H
# include <stdint.h> /* uintptr_t */
#else
# define uintptr_t size_t
#endif
#define NOT_POWER_OF_TWO(n) (((n) & ((n) - 1)))
#define UI(p) ((uintptr_t) (p))
#define CP(p) ((char *) p)
#define PTR_ALIGN(p0, alignment, offset) \
((void *) (((UI(p0) + (alignment + sizeof(void*)) + offset) \
& (~UI(alignment - 1))) \
- offset))
/* Pointer must sometimes be aligned; assume sizeof(void*) is a power of two. */
#define ORIG_PTR(p) (*(((void **) (UI(p) & (~UI(sizeof(void*) - 1)))) - 1))
void *
__mingw_aligned_offset_malloc (size_t size, size_t alignment, size_t offset)
{
void *p0, *p;
if (NOT_POWER_OF_TWO (alignment))
{
errno = EINVAL;
return ((void *) 0);
}
if (size == 0)
return ((void *) 0);
if (alignment < sizeof (void *))
alignment = sizeof (void *);
/* Including the extra sizeof(void*) is overkill on a 32-bit
machine, since malloc is already 8-byte aligned, as long
as we enforce alignment >= 8 ...but oh well. */
p0 = malloc (size + (alignment + sizeof (void *)));
if (!p0)
return ((void *) 0);
p = PTR_ALIGN (p0, alignment, offset);
ORIG_PTR (p) = p0;
return p;
}
void *
__mingw_aligned_malloc (size_t size, size_t alignment)
{
return __mingw_aligned_offset_malloc (size, alignment, 0);
}
void
__mingw_aligned_free (void *memblock)
{
if (memblock)
free (ORIG_PTR (memblock));
}
void *
__mingw_aligned_offset_realloc (void *memblock, size_t size,
size_t alignment, size_t offset)
{
void *p0, *p;
ptrdiff_t shift;
if (!memblock)
return __mingw_aligned_offset_malloc (size, alignment, offset);
if (NOT_POWER_OF_TWO (alignment))
goto bad;
if (size == 0)
{
__mingw_aligned_free (memblock);
return ((void *) 0);
}
if (alignment < sizeof (void *))
alignment = sizeof (void *);
p0 = ORIG_PTR (memblock);
/* It is an error for the alignment to change. */
if (memblock != PTR_ALIGN (p0, alignment, offset))
goto bad;
shift = CP (memblock) - CP (p0);
p0 = realloc (p0, size + (alignment + sizeof (void *)));
if (!p0)
return ((void *) 0);
p = PTR_ALIGN (p0, alignment, offset);
/* Relative shift of actual data may be different from before, ugh. */
if (shift != CP (p) - CP (p0))
/* ugh, moves more than necessary if size is increased. */
memmove (CP (p), CP (p0) + shift, size);
ORIG_PTR (p) = p0;
return p;
bad:
errno = EINVAL;
return ((void *) 0);
}
void *
__mingw_aligned_realloc (void *memblock, size_t size, size_t alignment)
{
return __mingw_aligned_offset_realloc (memblock, size, alignment, 0);
}
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