4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
33 * \brief Simple realtime multitasking scheduler.
34 * Context switching is only done cooperatively.
37 * \author Bernie Innocenti <bernie@codewiz.org>
38 * \author Stefano Fedrigo <aleph@develer.com>
44 #include "cfg/cfg_arch.h" /* ARCH_EMUL */
45 #include "cfg/cfg_kern.h"
46 #include <cfg/module.h>
49 #include <cpu/types.h>
51 #include <cpu/frame.h>
53 #include <string.h> /* memset() */
55 #if CONFIG_KERN_PREEMPT
60 * The scheduer tracks ready processes by enqueuing them in the
63 * \note Access to the list must occur while interrupts are disabled.
65 REGISTER List ProcReadyList;
68 * Holds a pointer to the TCB of the currently running process.
70 * \note User applications should use proc_current() to retrieve this value.
72 REGISTER Process *CurrentProcess;
74 #if (ARCH & ARCH_EMUL)
76 * In hosted environments, we must emulate the stack on the real process stack.
78 * Access to this list must be protected by PROC_ATOMIC().
80 extern List StackFreeList;
83 /** The main process (the one that executes main()). */
84 struct Process MainProcess;
87 static void proc_init_struct(Process *proc)
89 /* Avoid warning for unused argument. */
92 #if CONFIG_KERN_SIGNALS
96 #if CONFIG_KERN_PREEMPTIVE
109 LIST_INIT(&ProcReadyList);
112 * We "promote" the current context into a real process. The only thing we have
113 * to do is create a PCB and make it current. We don't need to setup the stack
114 * pointer because it will be written the first time we switch to another process.
116 proc_init_struct(&MainProcess);
117 CurrentProcess = &MainProcess;
119 #if CONFIG_KERN_MONITOR
121 monitor_add(CurrentProcess, "main");
124 #if CONFIG_KERN_PREEMPTIVE
133 * Create a new process, starting at the provided entry point.
135 * \return Process structure of new created process
136 * if successful, NULL otherwise.
138 struct Process *proc_new_with_name(UNUSED(const char *, name), void (*entry)(void), iptr_t data, size_t stack_size, cpustack_t *stack_base)
142 const size_t PROC_SIZE_WORDS = ROUND2(sizeof(Process), sizeof(cpustack_t)) / sizeof(cpustack_t);
144 bool free_stack = false;
146 TRACEMSG("name=%s", name);
148 #if (ARCH & ARCH_EMUL)
149 /* Ignore stack provided by caller and use the large enough default instead. */
150 PROC_ATOMIC(stack_base = (cpustack_t *)list_remHead(&StackFreeList));
152 stack_size = CONFIG_PROC_DEFSTACKSIZE;
153 #elif CONFIG_KERN_HEAP
154 /* Did the caller provide a stack for us? */
157 /* Did the caller specify the desired stack size? */
159 stack_size = CONFIG_PROC_DEFSTACKSIZE + sizeof(Process);
161 /* Allocate stack dinamically */
162 if (!(stack_base = heap_alloc(stack_size)))
168 /* Stack must have been provided by the user */
169 ASSERT_VALID_PTR(stack_base);
173 #if CONFIG_KERN_MONITOR
174 /* Fill-in the stack with a special marker to help debugging */
175 memset(stack_base, CONFIG_KERN_STACKFILLCODE, stack_size);
178 /* Initialize the process control block */
179 if (CPU_STACK_GROWS_UPWARD)
181 proc = (Process*)stack_base;
182 proc->stack = stack_base + PROC_SIZE_WORDS;
183 if (CPU_SP_ON_EMPTY_SLOT)
188 proc = (Process*)(stack_base + stack_size / sizeof(cpustack_t) - PROC_SIZE_WORDS);
189 proc->stack = (cpustack_t*)proc;
190 if (CPU_SP_ON_EMPTY_SLOT)
194 proc_init_struct(proc);
195 proc->user_data = data;
197 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR | (ARCH & ARCH_EMUL)
198 proc->stack_base = stack_base;
199 proc->stack_size = stack_size;
202 proc->flags |= PF_FREESTACK;
206 /* Initialize process stack frame */
207 CPU_PUSH_CALL_FRAME(proc->stack, proc_exit);
208 CPU_PUSH_CALL_FRAME(proc->stack, entry);
210 /* Push a clean set of CPU registers for asm_switch_context() */
211 for (i = 0; i < CPU_SAVED_REGS_CNT; i++)
212 CPU_PUSH_WORD(proc->stack, CPU_REG_INIT_VALUE(i));
214 /* Add to ready list */
215 ATOMIC(SCHED_ENQUEUE(proc));
216 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
218 #if CONFIG_KERN_MONITOR
219 monitor_add(proc, name);
225 /** Rename a process */
226 void proc_rename(struct Process *proc, const char *name)
228 #if CONFIG_KERN_MONITOR
229 monitor_rename(proc, name);
231 (void)proc; (void)name;
237 * Terminate the current process
243 #if CONFIG_KERN_MONITOR
244 monitor_remove(CurrentProcess);
249 * The following code is BROKEN.
250 * We are freeing our own stack before entering proc_schedule()
251 * BAJO: A correct fix would be to rearrange the scheduler with
252 * an additional parameter which frees the old stack/process
253 * after a context switch.
255 if (CurrentProcess->flags & PF_FREESTACK)
256 heap_free(CurrentProcess->stack_base, CurrentProcess->stack_size);
257 heap_free(CurrentProcess);
260 #if (ARCH & ARCH_EMUL)
261 #warning This is wrong
262 /* Reinsert process stack in free list */
263 PROC_ATOMIC(ADDHEAD(&StackFreeList, (Node *)(CurrentProcess->stack
264 - (CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)))));
267 * NOTE: At this point the first two words of what used
268 * to be our stack contain a list node. From now on, we
269 * rely on the compiler not reading/writing the stack.
271 #endif /* ARCH_EMUL */
273 CurrentProcess = NULL;
280 * Get the pointer to the current process
282 struct Process *proc_current(void)
284 return CurrentProcess;
288 * Get the pointer to the user data of the current process
290 iptr_t proc_current_user_data(void)
292 return CurrentProcess->user_data;