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