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/*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <ipxe/list.h>
#include <ipxe/init.h>
#include <ipxe/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 );
/**
* Get pointer to object containing process
*
* @v process Process
* @ret object Containing object
*/
void * process_object ( struct process *process ) {
return ( ( ( void * ) process ) - process->desc->offset );
}
/**
* Add process to process list
*
* @v process Process
*
* It is safe to call process_add() multiple times; further calls will
* have no effect.
*/
void process_add ( struct process *process ) {
if ( ! process_running ( process ) ) {
DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
" starting\n", PROC_DBG ( process ) );
ref_get ( process->refcnt );
list_add_tail ( &process->list, &run_queue );
} else {
DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
" already started\n", PROC_DBG ( process ) );
}
}
/**
* 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 ( process_running ( process ) ) {
DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
" stopping\n", PROC_DBG ( process ) );
list_del ( &process->list );
INIT_LIST_HEAD ( &process->list );
ref_put ( process->refcnt );
} else {
DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
" already stopped\n", PROC_DBG ( 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;
struct process_descriptor *desc;
void *object;
if ( ( process = list_first_entry ( &run_queue, struct process,
list ) ) ) {
ref_get ( process->refcnt ); /* Inhibit destruction mid-step */
desc = process->desc;
object = process_object ( process );
if ( desc->reschedule ) {
list_del ( &process->list );
list_add_tail ( &process->list, &run_queue );
} else {
process_del ( process );
}
DBGC2 ( PROC_COL ( process ), "PROCESS " PROC_FMT
" executing\n", PROC_DBG ( process ) );
desc->step ( object );
DBGC2 ( PROC_COL ( process ), "PROCESS " PROC_FMT
" finished executing\n", PROC_DBG ( process ) );
ref_put ( process->refcnt ); /* Allow destruction */
}
}
/**
* Initialise processes
*
*/
static void init_processes ( void ) {
struct process *process;
for_each_table_entry ( process, PERMANENT_PROCESSES )
process_add ( process );
}
/** Process initialiser */
struct init_fn process_init_fn __init_fn ( INIT_NORMAL ) = {
.initialise = init_processes,
};
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