X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/c846879ccf3e86ea293c157f4aa2ff8716fb5b4c..9b64ede2bf4a5475b4dd5a6cfab93488f0f60284:/sub.h diff --git a/sub.h b/sub.h index 1ebd35e..0731027 100644 --- a/sub.h +++ b/sub.h @@ -1,6 +1,6 @@ /* -*-c-*- * - * $Id: sub.h,v 1.2 1999/05/05 18:50:31 mdw Exp $ + * $Id: sub.h,v 1.8 2004/04/08 01:36:13 mdw Exp $ * * Allocation of known-size blocks * @@ -22,23 +22,13 @@ * GNU Library General Public License for more details. * * You should have received a copy of the GNU Library General Public - * License along with mLib; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * License along with mLib; if not, write to the Free + * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, + * MA 02111-1307, USA. */ -/*----- Revision history --------------------------------------------------* - * - * $Log: sub.h,v $ - * Revision 1.2 1999/05/05 18:50:31 mdw - * Change licensing conditions to LGPL. - * - * Revision 1.1.1.1 1998/06/17 23:44:42 mdw - * Initial version of mLib - * - */ - -#ifndef SUB_H -#define SUB_H +#ifndef MLIB_SUB_H +#define MLIB_SUB_H #ifdef __cplusplus extern "C" { @@ -48,27 +38,163 @@ #include -#ifndef ALLOC_H -# include "alloc.h" +#ifndef MLIB_ALIGN_H +# include "align.h" #endif +#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. + */ + +#define SUB_GRANULE sizeof(union align) + +/* --- 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@ --- * * @@ -80,11 +206,8 @@ void *sub_alloc(size_t s); * 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@ --- * * @@ -116,10 +239,11 @@ void sub_free(void *p, size_t s); * * Returns: --- * - * Use: Initialises 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 -------------------------------------------------*/