/* * Copyright (c) 2006 Jakub Jermar * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * - The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /** @addtogroup libc * @{ */ /** @file */ /* * This implementation of FIFO stores values in an array * (static or dynamic). As such, these FIFOs have upper bound * on number of values they can store. Push and pop operations * are done via accessing the array through head and tail indices. * Because of better operation ordering in fifo_pop(), the access * policy for these two indices is to 'increment (mod size of FIFO) * and use'. */ #ifndef _LIBC_FIFO_H_ #define _LIBC_FIFO_H_ #include <stdlib.h> typedef unsigned long fifo_count_t; typedef unsigned long fifo_index_t; #define FIFO_CREATE_STATIC(name, t, itms) \ struct { \ t fifo[(itms)]; \ fifo_count_t items; \ fifo_index_t head; \ fifo_index_t tail; \ } name /** Create and initialize static FIFO. * * FIFO is allocated statically. * This macro is suitable for creating smaller FIFOs. * * @param name Name of FIFO. * @param t Type of values stored in FIFO. * @param itms Number of items that can be stored in FIFO. */ #define FIFO_INITIALIZE_STATIC(name, t, itms) \ FIFO_CREATE_STATIC(name, t, itms) = { \ .items = (itms), \ .head = 0, \ .tail = 0 \ } /** Create and prepare dynamic FIFO. * * FIFO is allocated dynamically. * This macro is suitable for creating larger FIFOs. * * @param name Name of FIFO. * @param t Type of values stored in FIFO. * @param itms Number of items that can be stored in FIFO. */ #define FIFO_INITIALIZE_DYNAMIC(name, t, itms) \ struct { \ t *fifo; \ fifo_count_t items; \ fifo_index_t head; \ fifo_index_t tail; \ } name = { \ .fifo = NULL, \ .items = (itms), \ .head = 0, \ .tail = 0 \ } /** Pop value from head of FIFO. * * @param name FIFO name. * * @return Leading value in FIFO. */ #define fifo_pop(name) \ name.fifo[name.head = (name.head + 1) < name.items ? (name.head + 1) : 0] /** Push value to tail of FIFO. * * @param name FIFO name. * @param value Value to be appended to FIFO. * */ #define fifo_push(name, value) \ name.fifo[name.tail = (name.tail + 1) < name.items ? (name.tail + 1) : 0] = (value) /** Allocate memory for dynamic FIFO. * * @param name FIFO name. */ #define fifo_create(name) \ name.fifo = malloc(sizeof(*name.fifo) * name.items) #endif /** @} */