2004-08-24 Steven G. Johnson <stevenj@alum.mit.edu>

* mingwex/mingw-aligned-malloc.c: New file.
	* mingwex/tst-aligned-malloc.c: New file.

winsup/mingw/mingwex/mingw-aligned-malloc.c

@@ -0,0 +1,120 @@
+/*
+  __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);
+}