109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
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/* the Music Player Daemon (MPD)
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* Copyright (C) 2008 Max Kellermann <max@duempel.org>
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* This project's homepage is: http://www.musicpd.org
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "tag_pool.h"
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#include "utils.h"
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#define NUM_SLOTS 4096
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struct slot {
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struct slot *next;
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unsigned char ref;
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struct tag_item item;
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} mpd_packed;
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struct slot *slots[NUM_SLOTS];
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static inline unsigned
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calc_hash_n(enum tag_type type, const char *p, size_t length)
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{
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unsigned hash = 5381;
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assert(p != NULL);
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while (length-- > 0)
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hash = (hash << 5) + hash + *p++;
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return hash ^ type;
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}
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static inline unsigned
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calc_hash(enum tag_type type, const char *p)
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{
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unsigned hash = 5381;
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assert(p != NULL);
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while (*p != 0)
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hash = (hash << 5) + hash + *p++;
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return hash ^ type;
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}
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static inline struct slot *
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tag_item_to_slot(struct tag_item *item)
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{
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return (struct slot*)(((char*)item) - offsetof(struct slot, item));
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}
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struct tag_item *tag_pool_get_item(enum tag_type type,
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const char *value, int length)
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{
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struct slot **slot_p, *slot;
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slot_p = &slots[calc_hash_n(type, value, length) % NUM_SLOTS];
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for (slot = *slot_p; slot != NULL; slot = slot->next) {
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if (slot->item.type == type &&
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strcmp(value, slot->item.value) == 0 && slot->ref < 0xff) {
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assert(slot->ref > 0);
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++slot->ref;
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return &slot->item;
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}
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}
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slot = xmalloc(sizeof(*slot) + length);
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slot->next = *slot_p;
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slot->ref = 1;
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slot->item.type = type;
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memcpy(slot->item.value, value, length);
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slot->item.value[length] = 0;
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*slot_p = slot;
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return &slot->item;
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}
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void tag_pool_put_item(struct tag_item *item)
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{
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struct slot **slot_p, *slot;
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slot = tag_item_to_slot(item);
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assert(slot->ref > 0);
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--slot->ref;
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if (slot->ref > 0)
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return;
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for (slot_p = &slots[calc_hash(item->type, item->value) % NUM_SLOTS];
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*slot_p != slot;
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slot_p = &(*slot_p)->next) {
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assert(*slot_p != NULL);
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}
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*slot_p = slot->next;
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free(slot);
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}
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