1 files changed, 133 insertions, 0 deletions
diff --git a/roms/ipxe/src/core/process.c b/roms/ipxe/src/core/process.c
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+++ b/roms/ipxe/src/core/process.c
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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,
+};