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() */
57 * The scheduer tracks ready processes by enqueuing them in the
60 * \note Access to the list must occur while interrupts are disabled.
62 REGISTER List ProcReadyList;
65 * Holds a pointer to the TCB of the currently running process.
67 * \note User applications should use proc_current() to retrieve this value.
69 REGISTER Process *CurrentProcess;
71 #if (ARCH & ARCH_EMUL)
73 * In hosted environments, we must emulate the stack on the real process stack.
75 * Access to this list must be protected by PROC_ATOMIC().
77 extern List StackFreeList;
80 /** The main process (the one that executes main()). */
81 struct Process MainProcess;
84 static void proc_init_struct(Process *proc)
86 /* Avoid warning for unused argument. */
89 #if CONFIG_KERN_SIGNALS
93 #if CONFIG_KERN_PREEMPT
106 LIST_INIT(&ProcReadyList);
109 * We "promote" the current context into a real process. The only thing we have
110 * to do is create a PCB and make it current. We don't need to setup the stack
111 * pointer because it will be written the first time we switch to another process.
113 proc_init_struct(&MainProcess);
114 CurrentProcess = &MainProcess;
116 #if CONFIG_KERN_MONITOR
118 monitor_add(CurrentProcess, "main");
121 #if CONFIG_KERN_PREEMPT
130 * Create a new process, starting at the provided entry point.
132 * \return Process structure of new created process
133 * if successful, NULL otherwise.
135 struct Process *proc_new_with_name(UNUSED(const char *, name), void (*entry)(void), iptr_t data, size_t stack_size, cpustack_t *stack_base)
138 const size_t PROC_SIZE_WORDS = ROUND2(sizeof(Process), sizeof(cpustack_t)) / sizeof(cpustack_t);
140 bool free_stack = false;
142 TRACEMSG("name=%s", name);
144 #if (ARCH & ARCH_EMUL)
145 /* Ignore stack provided by caller and use the large enough default instead. */
146 PROC_ATOMIC(stack_base = (cpustack_t *)list_remHead(&StackFreeList));
148 stack_size = CONFIG_PROC_DEFSTACKSIZE;
149 #elif CONFIG_KERN_HEAP
150 /* Did the caller provide a stack for us? */
153 /* Did the caller specify the desired stack size? */
155 stack_size = CONFIG_PROC_DEFSTACKSIZE + sizeof(Process);
157 /* Allocate stack dinamically */
158 if (!(stack_base = heap_alloc(stack_size)))
164 /* Stack must have been provided by the user */
165 ASSERT_VALID_PTR(stack_base);
169 #if CONFIG_KERN_MONITOR
170 /* Fill-in the stack with a special marker to help debugging */
171 memset(stack_base, CONFIG_KERN_STACKFILLCODE, stack_size);
174 /* Initialize the process control block */
175 if (CPU_STACK_GROWS_UPWARD)
177 proc = (Process*)stack_base;
178 proc->stack = stack_base + PROC_SIZE_WORDS;
179 if (CPU_SP_ON_EMPTY_SLOT)
184 proc = (Process*)(stack_base + stack_size / sizeof(cpustack_t) - PROC_SIZE_WORDS);
185 proc->stack = (cpustack_t*)proc;
186 if (CPU_SP_ON_EMPTY_SLOT)
190 proc_init_struct(proc);
191 proc->user_data = data;
193 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR | (ARCH & ARCH_EMUL)
194 proc->stack_base = stack_base;
195 proc->stack_size = stack_size;
198 proc->flags |= PF_FREESTACK;
202 #if CONFIG_KERN_PREEMPT
204 getcontext(&proc->context);
205 proc->context.uc_stack.ss_sp = stack_base;
206 proc->context.uc_stack.ss_size = stack_size;
207 proc->context.uc_link = NULL;
208 makecontext(&proc->context, (void (*)(void))proc_entry, 1, entry);
210 #else // !CONFIG_KERN_PREEMPT
214 /* Initialize process stack frame */
215 CPU_PUSH_CALL_FRAME(proc->stack, proc_exit);
216 CPU_PUSH_CALL_FRAME(proc->stack, entry);
218 /* Push a clean set of CPU registers for asm_switch_context() */
219 for (i = 0; i < CPU_SAVED_REGS_CNT; i++)
220 CPU_PUSH_WORD(proc->stack, CPU_REG_INIT_VALUE(i));
222 #endif // CONFIG_KERN_PREEMPT
224 /* Add to ready list */
225 ATOMIC(SCHED_ENQUEUE(proc));
226 ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
228 #if CONFIG_KERN_MONITOR
229 monitor_add(proc, name);
235 /** Rename a process */
236 void proc_rename(struct Process *proc, const char *name)
238 #if CONFIG_KERN_MONITOR
239 monitor_rename(proc, name);
241 (void)proc; (void)name;
247 * Terminate the current process
251 TRACEMSG("%p:%s", CurrentProcess, CurrentProcess->monitor.name);
253 #if CONFIG_KERN_MONITOR
254 monitor_remove(CurrentProcess);
259 * The following code is BROKEN.
260 * We are freeing our own stack before entering proc_schedule()
261 * BAJO: A correct fix would be to rearrange the scheduler with
262 * an additional parameter which frees the old stack/process
263 * after a context switch.
265 if (CurrentProcess->flags & PF_FREESTACK)
266 heap_free(CurrentProcess->stack_base, CurrentProcess->stack_size);
267 heap_free(CurrentProcess);
270 #if (ARCH & ARCH_EMUL)
271 #warning This is wrong
272 /* Reinsert process stack in free list */
273 PROC_ATOMIC(ADDHEAD(&StackFreeList, (Node *)(CurrentProcess->stack
274 - (CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)))));
277 * NOTE: At this point the first two words of what used
278 * to be our stack contain a list node. From now on, we
279 * rely on the compiler not reading/writing the stack.
281 #endif /* ARCH_EMUL */
283 CurrentProcess = NULL;
290 * Get the pointer to the current process
292 struct Process *proc_current(void)
294 return CurrentProcess;
298 * Get the pointer to the user data of the current process
300 iptr_t proc_current_user_data(void)
302 return CurrentProcess->user_data;