unK
18 years ago
parent
77a01b6574
commit
ded070c61b
5 changed files with 214 additions and 47 deletions
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/* ncmpc
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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 "str_pool.h" |
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#include <assert.h> |
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#include <stddef.h> |
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#include <stdlib.h> |
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#include <string.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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char value[1]; |
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} __attribute__((packed)); |
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struct slot *slots[NUM_SLOTS]; |
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static inline unsigned |
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calc_hash(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; |
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} |
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static inline struct slot * |
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value_to_slot(char *value) |
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{ |
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return (struct slot*)(value - offsetof(struct slot, value)); |
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} |
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static struct slot *slot_alloc(struct slot *next, const char *value) |
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{ |
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size_t length = strlen(value); |
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struct slot *slot = malloc(sizeof(*slot) + length); |
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if (slot == NULL) |
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abort(); /* XXX */ |
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slot->next = next; |
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slot->ref = 1; |
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memcpy(slot->value, value, length + 1); |
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return slot; |
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} |
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char *str_pool_get(const char *value) |
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{ |
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struct slot **slot_p, *slot; |
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slot_p = &slots[calc_hash(value) % NUM_SLOTS]; |
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for (slot = *slot_p; slot != NULL; slot = slot->next) { |
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if (strcmp(value, slot->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->value; |
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} |
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} |
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slot = slot_alloc(*slot_p, value); |
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*slot_p = slot; |
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return slot->value; |
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} |
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char *str_pool_dup(char *value) |
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{ |
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struct slot *slot = value_to_slot(value); |
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assert(slot->ref > 0); |
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if (slot->ref < 0xff) { |
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++slot->ref; |
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return value; |
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} else { |
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/* the reference counter overflows above 0xff;
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duplicate the value, and start with 1 */ |
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struct slot **slot_p = |
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&slots[calc_hash(slot->value) % NUM_SLOTS]; |
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slot = slot_alloc(*slot_p, slot->value); |
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*slot_p = slot; |
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return slot->value; |
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} |
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} |
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void str_pool_put(char *value) |
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{ |
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struct slot **slot_p, *slot; |
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slot = value_to_slot(value); |
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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(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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@ -0,0 +1,37 @@ |
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/* ncmpc
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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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#ifndef STR_POOL_H |
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#define STR_POOL_H |
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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char *str_pool_get(const char *value); |
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char *str_pool_dup(char *value); |
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void str_pool_put(char *value); |
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#ifdef __cplusplus |
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} |
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#endif |
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#endif |
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