/*
* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
*
* 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <gpxe/list.h>
#include <gpxe/init.h>
#include <gpxe/process.h>
/** @file
*
* Processes
*
* We implement a trivial form of cooperative multitasking, in which
* all processes share a single stack and address space.
*/
/** Process run queue */
static LIST_HEAD ( run_queue );
/** Registered permanent processes */
static struct process processes[0]
__table_start ( struct process, processes );
static struct process processes_end[0]
__table_end ( struct process, processes );
/**
* Add process to process list
*
* @v process Process
*/
void process_add ( struct process *process ) {
DBGC ( process, "PROCESS %p starting\n", process );
ref_get ( process->refcnt );
list_add_tail ( &process->list, &run_queue );
}
/**
* Remove process from process list
*
* @v process Process
*
* It is safe to call process_del() multiple times; further calls will
* have no effect.
*/
void process_del ( struct process *process ) {
if ( ! list_empty ( &process->list ) ) {
DBGC ( process, "PROCESS %p stopping\n", process );
list_del ( &process->list );
INIT_LIST_HEAD ( &process->list );
ref_put ( process->refcnt );
} else {
DBGC ( process, "PROCESS %p already stopped\n", process );
}
}
/**
* Single-step a single process
*
* This executes a single step of the first process in the run queue,
* and moves the process to the end of the run queue.
*/
void step ( void ) {
struct process *process;
list_for_each_entry ( process, &run_queue, list ) {
list_del ( &process->list );
list_add_tail ( &process->list, &run_queue );
DBGC2 ( process, "PROCESS %p executing\n", process );
process->step ( process );
DBGC2 ( process, "PROCESS %p finished executing\n", process );
break;
}
}
/**
* Initialise processes
*
*/
static void init_processes ( void ) {
struct process *process;
for ( process = processes ; process < processes_end ; process++ ) {
process_add ( process );
}
}
/** Process initialiser */
struct init_fn process_init_fn __init_fn ( INIT_NORMAL ) = {
.initialise = init_processes,
};
