/* -*-c-*-
*
- * $Id: sub.h,v 1.5 1999/12/10 23:42:04 mdw Exp $
+ * $Id: sub.h,v 1.6 2000/06/17 10:35:51 mdw Exp $
*
* Allocation of known-size blocks
*
/*----- Revision history --------------------------------------------------*
*
* $Log: sub.h,v $
+ * Revision 1.6 2000/06/17 10:35:51 mdw
+ * Major overhaul for arena support.
+ *
* Revision 1.5 1999/12/10 23:42:04 mdw
* Change header file guard names.
*
#include <stdlib.h>
-#ifndef MLIB_ALLOC_H
-# include "alloc.h"
+#ifndef MLIB_ARENA_H
+# include "arena.h"
#endif
+/*----- Configuration and tuning ------------------------------------------*/
+
+/* --- The largest block I'll handle here --- *
+ *
+ * Anything larger will be handed on to the underlying @alloc@.
+ */
+
+#define SUB_MAXBIN 256
+
+/* --- Preferred chunk size --- *
+ *
+ * When a bin is empty, I'll allocate a large chunk of approximately this
+ * size and divvy it up into small bin-sized blocks.
+ */
+
+#define SUB_CHUNK 4096
+
+/*----- Other useful macros -----------------------------------------------*/
+
+/* --- The granularity of bin buffers --- *
+ *
+ * All blocks allocated by the binner are a multiple of this size. I've
+ * chosen @void *@ because I need to store @void *@ things in here.
+ */
+
+#define SUB_GRANULE sizeof(void *)
+
+/* --- Finding the right bin for a given size --- *
+ *
+ * This chooses the correct bin for an allocation. Input is the size of
+ * block wanted; result is the bin index.
+ */
+
+#define SUB_BIN(x) (((x) + SUB_GRANULE - 1) / SUB_GRANULE)
+
+/* --- Convert a bin back to the block size --- *
+ *
+ * This gives the size of block contained in a given bin.
+ */
+
+#define SUB_BINSZ(x) ((x) * SUB_GRANULE)
+
+/* --- Number of bins required --- */
+
+#define SUB_BINS (SUB_MAXBIN / SUB_GRANULE + 1)
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct subarena {
+ arena *a;
+ void *bin[SUB_BINS];
+} subarena;
+
+/*----- Global variables --------------------------------------------------*/
+
+extern subarena sub_global;
+
/*----- Functions provided ------------------------------------------------*/
+/* --- @subarena_create@ --- *
+ *
+ * Arguments: @subarena *s@ = pointer to arena to initialize
+ * @arena *a@ = pointer to underlying arena block
+ *
+ * Returns: ---
+ *
+ * Use: Initialize a suballocation arena based on an underlying large
+ * blocks arena.
+ */
+
+extern void subarena_create(subarena */*s*/, arena */*a*/);
+
+/* --- @subarena_destroy@ --- *
+ *
+ * Arguments: @subarena *s@ = pointer to arena to destroy
+ *
+ * Returns: ---
+ *
+ * Use: Destroys a suballocation arena, freeing all of the memory it
+ * contains back to the underlying large blocks arena.
+ */
+
+extern void subarena_destroy(subarena */*s*/);
+
+/* --- @subarena_alloc@ --- *
+ *
+ * Arguments: @subarena *s@ = pointer to arena
+ * @size_t s@ = size of chunk wanted
+ *
+ * Returns: Pointer to a block at least as large as the one wanted.
+ *
+ * Use: Allocates a small block of memory from the given pool. The
+ * exception @EXC_NOMEM@ is raised if the underlying arena is
+ * full.
+ */
+
+extern void *subarena_alloc(subarena */*s*/, size_t /*sz*/);
+
+/* --- @subarena_free@ --- *
+ *
+ * Arguments: @subarena *s@ = pointer to arena
+ * @void *p@ = address of block to free
+ * @size_t s@ = size of block
+ *
+ * Returns: ---
+ *
+ * Use: Frees a block allocated by @subarena_alloc@.
+ */
+
+extern void subarena_free(subarena */*s*/, void */*p*/, size_t /*sz*/);
+
+/* --- @A_CREATE@ --- *
+ *
+ * Arguments: @subarena *s@ = pointer to arena
+ * @type@ = type of object required; must be passable to
+ * @sizeof@
+ *
+ * Returns: Pointer to a block sufficiently big to hold an object of the
+ * named type.
+ *
+ * Use: Allocates a block of the required type.
+ */
+
+#define A_CREATE(a, type) subarena_alloc((a), sizeof(type))
+
+/* --- @A_DESTROY@ --- *
+ *
+ * Arguments: @subarena *s@ = pointer to arena
+ * @void *p@ = pointer to an object
+ *
+ * Returns: ---
+ *
+ * Use: Frees the thing pointed to by @p@.
+ */
+
+#define A_DESTROY(a, p) subarena_free((a), (p), sizeof(*p))
+
+/*----- Shortcuts for the global pool -------------------------------------*/
+
/* --- @sub_alloc@ --- *
*
* Arguments: @size_t s@ = size of chunk wanted
*
* Returns: Pointer to a block at least as large as the one wanted.
*
- * Use: Allocates a small block of memory. If there is no more
- * memory left, the exception @EXC_NOMEM@ is raised.
+ * Use: Allocates a small block of memory from the @sub_global@ pool.
*/
-#ifdef TRACK_ENABLE
-# define sub_alloc(s) xmalloc(s)
-#else
-void *sub_alloc(size_t s);
-#endif
+extern void *sub_alloc(size_t /*sz*/);
+#define sub_alloc(sz) subarena_alloc(&sub_global, (sz))
/* --- @sub_free@ --- *
*
* Use: Frees a block allocated by @sub_alloc@.
*/
-#ifdef TRACK_ENABLE
-# define sub_free(p, s) free(p)
-#else
-void sub_free(void *p, size_t s);
-#endif
+extern void sub_free(void */*p*/, size_t /*sz*/);
+#define sub_free(p, sz) subarena_free(&sub_global, (p), (sz))
/* --- @CREATE@ --- *
*
*
* Returns: ---
*
- * Use: Initializes the magic allocator.
+ * Use: Initializes the magic allocator. This is no longer
+ * necessary.
*/
-void sub_init(void);
+extern void sub_init(void);
/*----- That's all, folks -------------------------------------------------*/
~mdw / mLib / blobdiff