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author | Michael Brown | 2006-04-29 18:42:09 +0200 |
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committer | Michael Brown | 2006-04-29 18:42:09 +0200 |
commit | 23c494d14efafdd1dd06cec53665ddfd1c20fa34 (patch) | |
tree | 272441de75567c13f2d6075b771b0fad2ab1ba5a | |
parent | Give uIP a static IP address for proof-of-concept testing (diff) | |
download | ipxe-23c494d14efafdd1dd06cec53665ddfd1c20fa34.tar.gz ipxe-23c494d14efafdd1dd06cec53665ddfd1c20fa34.tar.xz ipxe-23c494d14efafdd1dd06cec53665ddfd1c20fa34.zip |
Added basic code for implementing co-operative multitasking.
Yes, you really can do it in 65 bytes.
-rw-r--r-- | src/core/process.c | 56 | ||||
-rw-r--r-- | src/include/gpxe/process.h | 32 |
2 files changed, 88 insertions, 0 deletions
diff --git a/src/core/process.c b/src/core/process.c new file mode 100644 index 00000000..c087f16d --- /dev/null +++ b/src/core/process.c @@ -0,0 +1,56 @@ +/* + * 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/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 ); + +/** + * Add process to run queue + * + * @v process Process + */ +void schedule ( struct process *process ) { + list_add_tail ( &process->list, &run_queue ); +} + +/** + * Single-step a single process + * + * This removes the first process from the run queue and executes a + * single step of that process. + */ +void step ( void ) { + struct process *process; + + list_for_each_entry ( process, &run_queue, list ) { + list_del ( &process->list ); + process->step ( process ); + break; + } +} diff --git a/src/include/gpxe/process.h b/src/include/gpxe/process.h new file mode 100644 index 00000000..83ff8393 --- /dev/null +++ b/src/include/gpxe/process.h @@ -0,0 +1,32 @@ +#ifndef _GPXE_PROCESS_H +#define _GPXE_PROCESS_H + +/** @file + * + * Processes + * + */ + +#include <gpxe/list.h> + +/** A process */ +struct process { + /** List of processes */ + struct list_head list; + /** + * Single-step the process + * + * This method should execute a single step of the process. + * Returning from this method is isomorphic to yielding the + * CPU to another process. + * + * If the process wishes to be executed again, it must re-add + * itself to the run queue using schedule(). + */ + void ( * step ) ( struct process *process ); +}; + +extern void schedule ( struct process *process ); +extern void step ( void ); + +#endif /* _GPXE_PROCESS_H */ |