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 // FIXME: move somewhere
56 #define CONFIG_DEPEND(FEATURE, DEPS) STATIC_ASSERT(!(FEATURE) || !!(DEPS))
58 CONFIG_DEPEND(CONFIG_KERN_PRI, CONFIG_KERN_PREEMPT);
62 * The scheduer tracks ready processes by enqueuing them in the
65 * \note Access to the list must occur while interrupts are disabled.
67 REGISTER List ProcReadyList;
70 * Holds a pointer to the TCB of the currently running process.
72 * \note User applications should use proc_current() to retrieve this value.
74 REGISTER Process *CurrentProcess;
76 #if (ARCH & ARCH_EMUL)
78 * In hosted environments, we must emulate the stack on the real process stack.
80 * Access to this list must be protected by PROC_ATOMIC().
82 extern List StackFreeList;
85 /** The main process (the one that executes main()). */
86 struct Process MainProcess;
89 static void proc_init_struct(Process *proc)
91 /* Avoid warning for unused argument. */
94 #if CONFIG_KERN_SIGNALS
111 LIST_INIT(&ProcReadyList);
114 * We "promote" the current context into a real process. The only thing we have
115 * to do is create a PCB and make it current. We don't need to setup the stack
116 * pointer because it will be written the first time we switch to another process.
118 proc_init_struct(&MainProcess);
119 CurrentProcess = &MainProcess;
121 #if CONFIG_KERN_MONITOR
123 monitor_add(CurrentProcess, "main");
126 #if CONFIG_KERN_PREEMPT
135 * Create a new process, starting at the provided entry point.
137 * \return Process structure of new created process
138 * if successful, NULL otherwise.
140 struct Process *proc_new_with_name(UNUSED(const char *, name), void (*entry)(void), iptr_t data, size_t stack_size, cpustack_t *stack_base)
143 const size_t PROC_SIZE_WORDS = ROUND2(sizeof(Process), sizeof(cpustack_t)) / sizeof(cpustack_t);
145 bool free_stack = false;
147 TRACEMSG("name=%s", name);
149 #if (ARCH & ARCH_EMUL)
150 /* Ignore stack provided by caller and use the large enough default instead. */
151 PROC_ATOMIC(stack_base = (cpustack_t *)list_remHead(&StackFreeList));
153 stack_size = CONFIG_KERN_MINSTACKSIZE;
154 #elif CONFIG_KERN_HEAP
155 /* Did the caller provide a stack for us? */
158 /* Did the caller specify the desired stack size? */
160 stack_size = CONFIG_KERN_MINSTACKSIZE;
162 /* Allocate stack dinamically */
163 if (!(stack_base = heap_alloc(stack_size)))
169 #else // !ARCH_EMUL && !CONFIG_KERN_HEAP
171 /* Stack must have been provided by the user */
172 ASSERT_VALID_PTR(stack_base);
175 #endif // !ARCH_EMUL && !CONFIG_KERN_HEAP
177 #if CONFIG_KERN_MONITOR
178 /* Fill-in the stack with a special marker to help debugging */
179 memset(stack_base, CONFIG_KERN_STACKFILLCODE, stack_size);
182 /* Initialize the process control block */
183 if (CPU_STACK_GROWS_UPWARD)
185 proc = (Process *)stack_base;
186 proc->stack = stack_base + PROC_SIZE_WORDS;
187 if (CPU_SP_ON_EMPTY_SLOT)
192 proc = (Process *)(stack_base + stack_size / sizeof(cpustack_t) - PROC_SIZE_WORDS);
193 proc->stack = (cpustack_t *)proc;
194 if (CPU_SP_ON_EMPTY_SLOT)
198 proc_init_struct(proc);
199 proc->user_data = data;
201 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR | (ARCH & ARCH_EMUL)
202 proc->stack_base = stack_base;
203 proc->stack_size = stack_size;
206 proc->flags |= PF_FREESTACK;
210 #if CONFIG_KERN_PREEMPT
212 getcontext(&proc->context);
213 proc->context.uc_stack.ss_sp = proc->stack;
214 proc->context.uc_stack.ss_size = stack_size - PROC_SIZE_WORDS - 1;
215 proc->context.uc_link = NULL;
216 makecontext(&proc->context, (void (*)(void))proc_entry, 1, entry);
218 #else // !CONFIG_KERN_PREEMPT
222 /* Initialize process stack frame */
223 CPU_PUSH_CALL_FRAME(proc->stack, proc_exit);
224 CPU_PUSH_CALL_FRAME(proc->stack, entry);
226 /* Push a clean set of CPU registers for asm_switch_context() */
227 for (i = 0; i < CPU_SAVED_REGS_CNT; i++)
228 CPU_PUSH_WORD(proc->stack, CPU_REG_INIT_VALUE(i));
230 #endif // CONFIG_KERN_PREEMPT
232 #if CONFIG_KERN_MONITOR
233 monitor_add(proc, name);
236 /* Add to ready list */
237 ATOMIC(SCHED_ENQUEUE(proc));
243 * Return the name of the specified process.
245 * NULL is a legal argument and will return the name "<NULL>".
247 const char *proc_name(struct Process *proc)
249 #if CONFIG_KERN_MONITOR
250 return proc ? proc->monitor.name : "<NULL>";
257 /// Return the name of the currently running process
258 const char *proc_currentName(void)
260 return proc_name(proc_current());
264 void proc_rename(struct Process *proc, const char *name)
266 #if CONFIG_KERN_MONITOR
267 monitor_rename(proc, name);
269 (void)proc; (void)name;
274 * Change the scheduling priority of a process.
276 * Process piorities are signed ints, whereas a larger integer value means
277 * higher scheduling priority. The default priority for new processes is 0.
278 * The idle process runs with the lowest possible priority: INT_MIN.
280 * A process with a higher priority always preempts lower priority processes.
281 * Processes of equal priority share the CPU time according to a simple
282 * round-robin policy.
284 * As a general rule to maximize responsiveness, compute-bound processes
285 * should be assigned negative priorities and tight, interactive processes
286 * should be assigned positive priorities.
288 * To avoid interfering with system background activities such as input
289 * processing, application processes should remain within the range -10
292 void proc_setPri(struct Process *proc, int pri)
294 if (proc->link.pri == pri)
297 proc->link.pri = pri;
299 if (proc != CurrentProcess)
302 //TODO: re-enqueue process
308 * Terminate the current process
312 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
314 #if CONFIG_KERN_MONITOR
315 monitor_remove(CurrentProcess);
320 * The following code is BROKEN.
321 * We are freeing our own stack before entering proc_schedule()
322 * BAJO: A correct fix would be to rearrange the scheduler with
323 * an additional parameter which frees the old stack/process
324 * after a context switch.
326 if (CurrentProcess->flags & PF_FREESTACK)
327 heap_free(CurrentProcess->stack_base, CurrentProcess->stack_size);
328 heap_free(CurrentProcess);
331 #if (ARCH & ARCH_EMUL)
332 /* Reinsert process stack in free list */
333 PROC_ATOMIC(ADDHEAD(&StackFreeList, (Node *)CurrentProcess->stack_base));
336 * NOTE: At this point the first two words of what used
337 * to be our stack contain a list node. From now on, we
338 * rely on the compiler not reading/writing the stack.
340 #endif /* ARCH_EMUL */
342 CurrentProcess = NULL;
349 * Get the pointer to the current process
351 struct Process *proc_current(void)
353 return CurrentProcess;
357 * Get the pointer to the user data of the current process
359 iptr_t proc_currentUserData(void)
361 return CurrentProcess->user_data;