/*
* 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.
*/
/*
* 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 __FIFO_H__
#define __FIFO_H__
#include <malloc.h>
typedef unsigned long fifo_count_t;
typedef unsigned long fifo_index_t;
/** 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) \
struct { \
t fifo[(itms)]; \
fifo_count_t items; \
fifo_index_t head; \
fifo_index_t tail; \
} name = { \
.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