add directory gnu

gnu/glibc/glibc-1.05.tar/glibc-1.05/malloc/realloc.c

@@ -0,0 +1,136 @@
+/* Change the size of a block allocated by `malloc'.
+   Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
+		     Written May 1989 by Mike Haertel.
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+This library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with this library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.
+
+   The author may be reached (Email) at the address mike@ai.mit.edu,
+   or (US mail) as Mike Haertel c/o Free Software Foundation.  */
+
+#ifndef	_MALLOC_INTERNAL
+#define _MALLOC_INTERNAL
+#include <malloc.h>
+#endif
+
+#define min(A, B) ((A) < (B) ? (A) : (B))
+
+/* Debugging hook for realloc.  */
+__ptr_t (*__realloc_hook) __P ((__ptr_t __ptr, size_t __size));
+
+/* Resize the given region to the new size, returning a pointer
+   to the (possibly moved) region.  This is optimized for speed;
+   some benchmarks seem to indicate that greater compactness is
+   achieved by unconditionally allocating and copying to a
+   new region.  This module has incestuous knowledge of the
+   internals of both free and malloc. */
+__ptr_t
+realloc (ptr, size)
+     __ptr_t ptr;
+     size_t size;
+{
+  __ptr_t result;
+  int type;
+  size_t block, blocks, oldlimit;
+
+  if (size == 0)
+    {
+      free (ptr);
+      return malloc (0);
+    }
+  else if (ptr == NULL)
+    return malloc (size);
+
+  if (__realloc_hook != NULL)
+    return (*__realloc_hook) (ptr, size);
+
+  block = BLOCK (ptr);
+
+  type = _heapinfo[block].busy.type;
+  switch (type)
+    {
+    case 0:
+      /* Maybe reallocate a large block to a small fragment.  */
+      if (size <= BLOCKSIZE / 2)
+	{
+	  result = malloc (size);
+	  if (result != NULL)
+	    {
+	      memcpy (result, ptr, size);
+	      free (ptr);
+	      return result;
+	    }
+	}
+
+      /* The new size is a large allocation as well;
+	 see if we can hold it in place. */
+      blocks = BLOCKIFY (size);
+      if (blocks < _heapinfo[block].busy.info.size)
+	{
+	  /* The new size is smaller; return
+	     excess memory to the free list. */
+	  _heapinfo[block + blocks].busy.type = 0;
+	  _heapinfo[block + blocks].busy.info.size
+	    = _heapinfo[block].busy.info.size - blocks;
+	  _heapinfo[block].busy.info.size = blocks;
+	  free (ADDRESS (block + blocks));
+	  result = ptr;
+	}
+      else if (blocks == _heapinfo[block].busy.info.size)
+	/* No size change necessary.  */
+	result = ptr;
+      else
+	{
+	  /* Won't fit, so allocate a new region that will.
+	     Free the old region first in case there is sufficient
+	     adjacent free space to grow without moving. */
+	  blocks = _heapinfo[block].busy.info.size;
+	  /* Prevent free from actually returning memory to the system.  */
+	  oldlimit = _heaplimit;
+	  _heaplimit = 0;
+	  free (ptr);
+	  _heaplimit = oldlimit;
+	  result = malloc (size);
+	  if (result == NULL)
+	    {
+	      (void) malloc (blocks * BLOCKSIZE);
+	      return NULL;
+	    }
+	  if (ptr != result)
+	    memmove (result, ptr, blocks * BLOCKSIZE);
+	}
+      break;
+
+    default:
+      /* Old size is a fragment; type is logarithm
+	 to base two of the fragment size.  */
+      if (size > (size_t) (1 << (type - 1)) && size <= (size_t) (1 << type))
+	/* The new size is the same kind of fragment.  */
+	result = ptr;
+      else
+	{
+	  /* The new size is different; allocate a new space,
+	     and copy the lesser of the new size and the old. */
+	  result = malloc (size);
+	  if (result == NULL)
+	    return NULL;
+	  memcpy (result, ptr, min (size, (size_t) 1 << type));
+	  free (ptr);
+	}
+      break;
+    }
+
+  return result;
+}