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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* This is a memory allocator designed to provide reasonable management of free
* space and fast access to allocated data. More than one allocator can be used
* at a time by initializing multiple contexts.
*
* Copyright (C) 2009 Andrew Mahone
* Copyright (C) 2011 Thomas Martitz
*
* 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
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#ifndef _BUFLIB_MEMPOOL_H_
#define _BUFLIB_MEMPOOL_H_
#ifndef _BUFLIB_H_
# error "include buflib.h instead"
#endif
#include "system.h"
/* Indices used to access block fields as block[BUFLIB_IDX_XXX] */
enum {
BUFLIB_IDX_LEN, /* length of the block, must come first */
BUFLIB_IDX_HANDLE, /* pointer to entry in the handle table */
BUFLIB_IDX_OPS, /* pointer to an ops struct */
BUFLIB_IDX_PIN, /* pin count */
BUFLIB_NUM_FIELDS,
};
union buflib_data
{
intptr_t val; /* length of the block in n*sizeof(union buflib_data).
Includes buflib metadata overhead. A negative value
indicates block is unallocated */
volatile unsigned pincount; /* number of pins */
struct buflib_callbacks* ops; /* callback functions for move and shrink. Can be NULL */
char* alloc; /* start of allocated memory area */
union buflib_data *handle; /* pointer to entry in the handle table.
Used during compaction for fast lookup */
};
struct buflib_context
{
union buflib_data *handle_table;
union buflib_data *first_free_handle;
union buflib_data *last_handle;
union buflib_data *buf_start;
union buflib_data *alloc_end;
bool compact;
};
#define BUFLIB_ALLOC_OVERHEAD (BUFLIB_NUM_FIELDS * sizeof(union buflib_data))
#ifndef BUFLIB_DEBUG_GET_DATA
static inline void *buflib_get_data(struct buflib_context *ctx, int handle)
{
return (void *)ctx->handle_table[-handle].alloc;
}
#endif
static inline union buflib_data *_buflib_get_block_header(void *data)
{
union buflib_data *bd = ALIGN_DOWN(data, sizeof(*bd));
return bd - BUFLIB_NUM_FIELDS;
}
static inline void *buflib_get_data_pinned(struct buflib_context *ctx, int handle)
{
void *data = buflib_get_data(ctx, handle);
union buflib_data *bd = _buflib_get_block_header(data);
bd[BUFLIB_IDX_PIN].pincount++;
return data;
}
static inline void buflib_put_data_pinned(struct buflib_context *ctx, void *data)
{
(void)ctx;
union buflib_data *bd = _buflib_get_block_header(data);
bd[BUFLIB_IDX_PIN].pincount--;
}
#endif /* _BUFLIB_MEMPOOL_H_ */
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