/*
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* Copyright (c) 2014, Linaro Limited
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License Version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/slab.h>
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#include <linux/string.h>
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#include "handle.h"
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/*
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* Define the initial capacity of the database. It should be a low number
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* multiple of 2 since some databases a likely to only use a few handles.
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* Since the algorithm is to doubles up when growing it shouldn't cause a
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* noticable overhead on large databases.
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*/
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#define HANDLE_DB_INITIAL_MAX_PTRS 4
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void handle_db_destroy(struct handle_db *db)
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{
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if (db) {
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kfree(db->ptrs);
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db->ptrs = NULL;
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db->max_ptrs = 0;
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}
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}
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int handle_get(struct handle_db *db, void *ptr)
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{
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unsigned n;
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void *p;
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unsigned new_max_ptrs;
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if (!db || !ptr)
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return -1;
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/* Try to find an empty location */
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for (n = 0; n < db->max_ptrs; n++) {
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if (!db->ptrs[n]) {
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db->ptrs[n] = ptr;
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return n;
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}
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}
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/* No location available, grow the ptrs array */
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if (db->max_ptrs)
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new_max_ptrs = db->max_ptrs * 2;
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else
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new_max_ptrs = HANDLE_DB_INITIAL_MAX_PTRS;
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p = krealloc(db->ptrs, new_max_ptrs * sizeof(void *), GFP_KERNEL);
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if (!p)
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return -1;
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db->ptrs = p;
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memset(db->ptrs + db->max_ptrs, 0,
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(new_max_ptrs - db->max_ptrs) * sizeof(void *));
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db->max_ptrs = new_max_ptrs;
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/* Since n stopped at db->max_ptrs there is an empty location there */
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db->ptrs[n] = ptr;
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return n;
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}
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void *handle_put(struct handle_db *db, int handle)
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{
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void *p;
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if (!db || handle < 0 || (unsigned)handle >= db->max_ptrs)
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return NULL;
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p = db->ptrs[handle];
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db->ptrs[handle] = NULL;
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return p;
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}
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void *handle_lookup(struct handle_db *db, int handle)
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{
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if (!db || handle < 0 || (unsigned)handle >= db->max_ptrs)
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return NULL;
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return db->ptrs[handle];
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}
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