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authorStan Shebs <shebs@codesourcery.com>1999-04-16 01:35:26 +0000
committerStan Shebs <shebs@codesourcery.com>1999-04-16 01:35:26 +0000
commitc906108c21474dfb4ed285bcc0ac6fe02cd400cc (patch)
treea0015aa5cedc19ccbab307251353a41722a3ae13 /mmalloc/mrealloc.c
parentcd946cff9ede3f30935803403f06f6ed30cad136 (diff)
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Initial creation of sourceware repositorygdb-4_18-branchpoint
Diffstat (limited to 'mmalloc/mrealloc.c')
-rw-r--r--mmalloc/mrealloc.c163
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diff --git a/mmalloc/mrealloc.c b/mmalloc/mrealloc.c
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+/* Change the size of a block allocated by `mmalloc'.
+ Copyright 1990, 1991 Free Software Foundation
+ Written May 1989 by Mike Haertel.
+
+The GNU C 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.
+
+The GNU C 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 the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, 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. */
+
+#include <string.h> /* Prototypes for memcpy, memmove, memset, etc */
+
+#include "mmprivate.h"
+
+/* 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 mfree and mmalloc. */
+
+PTR
+mrealloc (md, ptr, size)
+ PTR md;
+ PTR ptr;
+ size_t size;
+{
+ struct mdesc *mdp;
+ PTR result;
+ int type;
+ size_t block, blocks, oldlimit;
+
+ if (size == 0)
+ {
+ mfree (md, ptr);
+ return (mmalloc (md, 0));
+ }
+ else if (ptr == NULL)
+ {
+ return (mmalloc (md, size));
+ }
+
+ mdp = MD_TO_MDP (md);
+
+ if (mdp -> mrealloc_hook != NULL)
+ {
+ return ((*mdp -> mrealloc_hook) (md, ptr, size));
+ }
+
+ block = BLOCK (ptr);
+
+ type = mdp -> heapinfo[block].busy.type;
+ switch (type)
+ {
+ case 0:
+ /* Maybe reallocate a large block to a small fragment. */
+ if (size <= BLOCKSIZE / 2)
+ {
+ result = mmalloc (md, size);
+ if (result != NULL)
+ {
+ memcpy (result, ptr, size);
+ mfree (md, 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 < mdp -> heapinfo[block].busy.info.size)
+ {
+ /* The new size is smaller; return excess memory to the free list. */
+ mdp -> heapinfo[block + blocks].busy.type = 0;
+ mdp -> heapinfo[block + blocks].busy.info.size
+ = mdp -> heapinfo[block].busy.info.size - blocks;
+ mdp -> heapinfo[block].busy.info.size = blocks;
+ mfree (md, ADDRESS (block + blocks));
+ result = ptr;
+ }
+ else if (blocks == mdp -> 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 = mdp -> heapinfo[block].busy.info.size;
+ /* Prevent free from actually returning memory to the system. */
+ oldlimit = mdp -> heaplimit;
+ mdp -> heaplimit = 0;
+ mfree (md, ptr);
+ mdp -> heaplimit = oldlimit;
+ result = mmalloc (md, size);
+ if (result == NULL)
+ {
+ mmalloc (md, 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 = mmalloc (md, size);
+ if (result == NULL)
+ {
+ return (NULL);
+ }
+ memcpy (result, ptr, MIN (size, (size_t) 1 << type));
+ mfree (md, ptr);
+ }
+ break;
+ }
+
+ return (result);
+}
+
+/* When using this package, provide a version of malloc/realloc/free built
+ on top of it, so that if we use the default sbrk() region we will not
+ collide with another malloc package trying to do the same thing, if
+ the application contains any "hidden" calls to malloc/realloc/free (such
+ as inside a system library). */
+
+PTR
+realloc (ptr, size)
+ PTR ptr;
+ size_t size;
+{
+ PTR result;
+
+ result = mrealloc ((PTR) NULL, ptr, size);
+ return (result);
+}