/* * Copyright (C) 2003-2011 The Music Player Daemon Project * http://www.musicpd.org * * 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 program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ /** \file * * This is a library which manages reference counted buffers. */ #ifndef MPD_PAGE_H #define MPD_PAGE_H #include <stddef.h> #include <stdbool.h> /** * A dynamically allocated buffer which keeps track of its reference * count. This is useful for passing buffers around, when several * instances hold references to one buffer. */ struct page { /** * The number of references to this buffer. This library uses * atomic functions to access it, i.e. no locks are required. * As soon as this attribute reaches zero, the buffer is * freed. */ int ref; /** * The size of this buffer in bytes. */ size_t size; /** * Dynamic array containing the buffer data. */ unsigned char data[sizeof(long)]; }; /** * Creates a new #page object, and copies data from the specified * buffer. It is initialized with a reference count of 1. * * @param data the source buffer * @param size the size of the source buffer * @return the new #page object */ struct page * page_new_copy(const void *data, size_t size); /** * Concatenates two pages to a new page. * * @param a the first page * @param b the second page, which is appended */ struct page * page_new_concat(const struct page *a, const struct page *b); /** * Increases the reference counter. * * @param page the #page object */ void page_ref(struct page *page); /** * Decreases the reference counter. If it reaches zero, the #page is * freed. * * @param page the #page object * @return true if the #page has been freed */ bool page_unref(struct page *page); #endif