19990502 sourceware importbinu_ss_19990502

1 files changed, 291 insertions, 0 deletions

diff --git a/libiberty/objalloc.c b/libiberty/objalloc.c
new file mode 100644
index 0000000..57754a8
--- /dev/null
+++ b/libiberty/objalloc.c
@@ -0,0 +1,291 @@
+/* objalloc.c -- routines to allocate memory for objects
+   Copyright 1997 Free Software Foundation, Inc.
+   Written by Ian Lance Taylor, Cygnus Solutions.
+
+This program is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+This program 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+#include "ansidecl.h"
+#include "objalloc.h"
+
+/* Get a definition for NULL.  */
+#include <stdio.h>
+
+#if VMS
+#include <stdlib.h>
+#include <unixlib.h>
+#else
+
+#ifdef ANSI_PROTOTYPES
+/* Get a definition for size_t.  */
+#include <stddef.h>
+#endif
+
+/* For systems with larger pointers than ints, this must be declared.  */
+extern PTR malloc PARAMS ((size_t));
+extern void free PARAMS ((PTR));
+#endif
+
+/* These routines allocate space for an object.  Freeing allocated
+   space may or may not free all more recently allocated space.
+
+   We handle large and small allocation requests differently.  If we
+   don't have enough space in the current block, and the allocation
+   request is for more than 512 bytes, we simply pass it through to
+   malloc.  */
+
+/* The objalloc structure is defined in objalloc.h.  */
+
+/* This structure appears at the start of each chunk.  */
+
+struct objalloc_chunk
+{
+  /* Next chunk.  */
+  struct objalloc_chunk *next;
+  /* If this chunk contains large objects, this is the value of
+     current_ptr when this chunk was allocated.  If this chunk
+     contains small objects, this is NULL.  */
+  char *current_ptr;
+};
+
+/* The aligned size of objalloc_chunk.  */
+
+#define CHUNK_HEADER_SIZE					\
+  ((sizeof (struct objalloc_chunk) + OBJALLOC_ALIGN - 1)	\
+   &~ (OBJALLOC_ALIGN - 1))
+
+/* We ask for this much memory each time we create a chunk which is to
+   hold small objects.  */
+
+#define CHUNK_SIZE (4096 - 32)
+
+/* A request for this amount or more is just passed through to malloc.  */
+
+#define BIG_REQUEST (512)
+
+/* Create an objalloc structure.  */
+
+struct objalloc *
+objalloc_create ()
+{
+  struct objalloc *ret;
+  struct objalloc_chunk *chunk;
+
+  ret = (struct objalloc *) malloc (sizeof *ret);
+  if (ret == NULL)
+    return NULL;
+
+  ret->chunks = (PTR) malloc (CHUNK_SIZE);
+  if (ret->chunks == NULL)
+    {
+      free (ret);
+      return NULL;
+    }
+
+  chunk = (struct objalloc_chunk *) ret->chunks;
+  chunk->next = NULL;
+  chunk->current_ptr = NULL;
+
+  ret->current_ptr = (char *) chunk + CHUNK_HEADER_SIZE;
+  ret->current_space = CHUNK_SIZE - CHUNK_HEADER_SIZE;
+
+  return ret;
+}
+
+/* Allocate space from an objalloc structure.  */
+
+PTR
+_objalloc_alloc (o, len)
+     struct objalloc *o;
+     unsigned long len;
+{
+  /* We avoid confusion from zero sized objects by always allocating
+     at least 1 byte.  */
+  if (len == 0)
+    len = 1;
+
+  len = (len + OBJALLOC_ALIGN - 1) &~ (OBJALLOC_ALIGN - 1);
+
+  if (len <= o->current_space)
+    {
+      o->current_ptr += len;
+      o->current_space -= len;
+      return (PTR) (o->current_ptr - len);
+    }
+
+  if (len >= BIG_REQUEST)
+    {
+      char *ret;
+      struct objalloc_chunk *chunk;
+
+      ret = (char *) malloc (CHUNK_HEADER_SIZE + len);
+      if (ret == NULL)
+	return NULL;
+
+      chunk = (struct objalloc_chunk *) ret;
+      chunk->next = (struct objalloc_chunk *) o->chunks;
+      chunk->current_ptr = o->current_ptr;
+
+      o->chunks = (PTR) chunk;
+
+      return (PTR) (ret + CHUNK_HEADER_SIZE);
+    }
+  else
+    {
+      struct objalloc_chunk *chunk;
+
+      chunk = (struct objalloc_chunk *) malloc (CHUNK_SIZE);
+      if (chunk == NULL)
+	return NULL;
+      chunk->next = (struct objalloc_chunk *) o->chunks;
+      chunk->current_ptr = NULL;
+
+      o->current_ptr = (char *) chunk + CHUNK_HEADER_SIZE;
+      o->current_space = CHUNK_SIZE - CHUNK_HEADER_SIZE;
+
+      o->chunks = (PTR) chunk;
+
+      return objalloc_alloc (o, len);
+    }
+}
+
+/* Free an entire objalloc structure.  */
+
+void
+objalloc_free (o)
+     struct objalloc *o;
+{
+  struct objalloc_chunk *l;
+
+  l = (struct objalloc_chunk *) o->chunks;
+  while (l != NULL)
+    {
+      struct objalloc_chunk *next;
+
+      next = l->next;
+      free (l);
+      l = next;
+    }
+
+  free (o);
+}
+
+/* Free a block from an objalloc structure.  This also frees all more
+   recently allocated blocks.  */
+
+void
+objalloc_free_block (o, block)
+     struct objalloc *o;
+     PTR block;
+{
+  struct objalloc_chunk *p, *small;
+  char *b = (char *) block;
+
+  /* First set P to the chunk which contains the block we are freeing,
+     and set Q to the last small object chunk we see before P.  */
+  small = NULL;
+  for (p = (struct objalloc_chunk *) o->chunks; p != NULL; p = p->next)
+    {
+      if (p->current_ptr == NULL)
+	{
+	  if (b > (char *) p && b < (char *) p + CHUNK_SIZE)
+	    break;
+	  small = p;
+	}
+      else
+	{
+	  if (b == (char *) p + CHUNK_HEADER_SIZE)
+	    break;
+	}
+    }
+
+  /* If we can't find the chunk, the caller has made a mistake.  */
+  if (p == NULL)
+    abort ();
+
+  if (p->current_ptr == NULL)
+    {
+      struct objalloc_chunk *q;
+      struct objalloc_chunk *first;
+
+      /* The block is in a chunk containing small objects.  We can
+	 free every chunk through SMALL, because they have certainly
+	 been allocated more recently.  After SMALL, we will not see
+	 any chunks containing small objects; we can free any big
+	 chunk if the current_ptr is greater than or equal to B.  We
+	 can then reset the new current_ptr to B.  */
+
+      first = NULL;
+      q = (struct objalloc_chunk *) o->chunks;
+      while (q != p)
+	{
+	  struct objalloc_chunk *next;
+
+	  next = q->next;
+	  if (small != NULL)
+	    {
+	      if (small == q)
+		small = NULL;
+	      free (q);
+	    }
+	  else if (q->current_ptr > b)
+	    free (q);
+	  else if (first == NULL)
+	    first = q;
+
+	  q = next;
+	}
+
+      if (first == NULL)
+	first = p;
+      o->chunks = (PTR) first;
+
+      /* Now start allocating from this small block again.  */
+      o->current_ptr = b;
+      o->current_space = ((char *) p + CHUNK_SIZE) - b;
+    }
+  else
+    {
+      struct objalloc_chunk *q;
+      char *current_ptr;
+
+      /* This block is in a large chunk by itself.  We can free
+         everything on the list up to and including this block.  We
+         then start allocating from the next chunk containing small
+         objects, setting current_ptr from the value stored with the
+         large chunk we are freeing.  */
+
+      current_ptr = p->current_ptr;
+      p = p->next;
+
+      q = (struct objalloc_chunk *) o->chunks;
+      while (q != p)
+	{
+	  struct objalloc_chunk *next;
+
+	  next = q->next;
+	  free (q);
+	  q = next;
+	}
+
+      o->chunks = (PTR) p;
+
+      while (p->current_ptr != NULL)
+	p = p->next;
+
+      o->current_ptr = current_ptr;
+      o->current_space = ((char *) p + CHUNK_SIZE) - current_ptr;
+    }
+}