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 cooperative multitasking scheduler.
36 * \author Bernie Innocenti <bernie@codewiz.org>
37 * \author Stefano Fedrigo <aleph@develer.com>
43 #include "cfg/cfg_arch.h" /* ARCH_EMUL */
44 #include "cfg/cfg_kern.h"
45 #include <cfg/module.h>
46 #include <cfg/depend.h> // CONFIG_DEPEND()
49 #include <cpu/types.h>
51 #include <cpu/frame.h>
54 #include <struct/heap.h>
57 #include <string.h> /* memset() */
59 // Check config dependencies
60 CONFIG_DEPEND(CONFIG_KERN_SIGNALS, CONFIG_KERN_SCHED);
61 CONFIG_DEPEND(CONFIG_KERN_SEMAPHORES, CONFIG_KERN_SIGNALS);
62 CONFIG_DEPEND(CONFIG_KERN_MONITOR, CONFIG_KERN_SCHED);
66 * The scheduer tracks ready processes by enqueuing them in the
69 * \note Access to the list must occur while interrupts are disabled.
71 REGISTER List ProcReadyList;
74 * Holds a pointer to the TCB of the currently running process.
76 * \note User applications should use proc_current() to retrieve this value.
78 REGISTER Process *CurrentProcess;
80 #if (ARCH & ARCH_EMUL)
82 * In some hosted environments, we must emulate the stack on the real
83 * process stack to satisfy consistency checks in system libraries and
84 * because some ABIs place trampolines on the stack.
86 * Access to this list must be protected by PROC_ATOMIC().
91 cpustack_t proc_stacks[NPROC][(64 * 1024) / sizeof(cpustack_t)];
94 /** The main process (the one that executes main()). */
95 struct Process MainProcess;
98 static void proc_init_struct(Process *proc)
100 /* Avoid warning for unused argument. */
103 #if CONFIG_KERN_SIGNALS
120 LIST_INIT(&ProcReadyList);
123 LIST_INIT(&StackFreeList);
124 for (int i = 0; i < NPROC; i++)
125 ADDTAIL(&StackFreeList, (Node *)proc_stacks[i]);
129 * We "promote" the current context into a real process. The only thing we have
130 * to do is create a PCB and make it current. We don't need to setup the stack
131 * pointer because it will be written the first time we switch to another process.
133 proc_init_struct(&MainProcess);
134 CurrentProcess = &MainProcess;
136 #if CONFIG_KERN_MONITOR
138 monitor_add(CurrentProcess, "main");
141 #if CONFIG_KERN_PREEMPT
149 * Create a new process, starting at the provided entry point.
151 * \return Process structure of new created process
152 * if successful, NULL otherwise.
154 struct Process *proc_new_with_name(UNUSED_ARG(const char *, name), void (*entry)(void), iptr_t data, size_t stack_size, cpustack_t *stack_base)
157 const size_t PROC_SIZE_WORDS = ROUND_UP2(sizeof(Process), sizeof(cpustack_t)) / sizeof(cpustack_t);
159 bool free_stack = false;
161 TRACEMSG("name=%s", name);
163 #if (ARCH & ARCH_EMUL)
164 /* Ignore stack provided by caller and use the large enough default instead. */
165 PROC_ATOMIC(stack_base = (cpustack_t *)list_remHead(&StackFreeList));
167 stack_size = CONFIG_KERN_MINSTACKSIZE;
168 #elif CONFIG_KERN_HEAP
169 /* Did the caller provide a stack for us? */
172 /* Did the caller specify the desired stack size? */
174 stack_size = CONFIG_KERN_MINSTACKSIZE;
176 /* Allocate stack dinamically */
177 if (!(stack_base = heap_alloc(stack_size)))
183 #else // !ARCH_EMUL && !CONFIG_KERN_HEAP
185 /* Stack must have been provided by the user */
186 ASSERT_VALID_PTR(stack_base);
189 #endif // !ARCH_EMUL && !CONFIG_KERN_HEAP
191 #if CONFIG_KERN_MONITOR
192 /* Fill-in the stack with a special marker to help debugging */
193 memset(stack_base, CONFIG_KERN_STACKFILLCODE, stack_size);
196 /* Initialize the process control block */
197 if (CPU_STACK_GROWS_UPWARD)
199 proc = (Process *)stack_base;
200 proc->stack = stack_base + PROC_SIZE_WORDS;
201 if (CPU_SP_ON_EMPTY_SLOT)
206 proc = (Process *)(stack_base + stack_size / sizeof(cpustack_t) - PROC_SIZE_WORDS);
207 proc->stack = (cpustack_t *)proc;
208 if (CPU_SP_ON_EMPTY_SLOT)
212 proc_init_struct(proc);
213 proc->user_data = data;
215 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR | (ARCH & ARCH_EMUL)
216 proc->stack_base = stack_base;
217 proc->stack_size = stack_size;
220 proc->flags |= PF_FREESTACK;
224 #if CONFIG_KERN_PREEMPT
226 getcontext(&proc->context);
227 proc->context.uc_stack.ss_sp = proc->stack;
228 proc->context.uc_stack.ss_size = stack_size - PROC_SIZE_WORDS - 1;
229 proc->context.uc_link = NULL;
230 makecontext(&proc->context, (void (*)(void))proc_entry, 1, entry);
232 #else // !CONFIG_KERN_PREEMPT
236 /* Initialize process stack frame */
237 CPU_PUSH_CALL_FRAME(proc->stack, proc_exit);
238 CPU_PUSH_CALL_FRAME(proc->stack, entry);
240 /* Push a clean set of CPU registers for asm_switch_context() */
241 for (i = 0; i < CPU_SAVED_REGS_CNT; i++)
242 CPU_PUSH_WORD(proc->stack, CPU_REG_INIT_VALUE(i));
244 #endif // CONFIG_KERN_PREEMPT
246 #if CONFIG_KERN_MONITOR
247 monitor_add(proc, name);
250 /* Add to ready list */
251 ATOMIC(SCHED_ENQUEUE(proc));
257 * Return the name of the specified process.
259 * NULL is a legal argument and will return the name "<NULL>".
261 const char *proc_name(struct Process *proc)
263 #if CONFIG_KERN_MONITOR
264 return proc ? proc->monitor.name : "<NULL>";
271 /// Return the name of the currently running process
272 const char *proc_currentName(void)
274 return proc_name(proc_current());
278 void proc_rename(struct Process *proc, const char *name)
280 #if CONFIG_KERN_MONITOR
281 monitor_rename(proc, name);
283 (void)proc; (void)name;
290 * Change the scheduling priority of a process.
292 * Process piorities are signed ints, whereas a larger integer value means
293 * higher scheduling priority. The default priority for new processes is 0.
294 * The idle process runs with the lowest possible priority: INT_MIN.
296 * A process with a higher priority always preempts lower priority processes.
297 * Processes of equal priority share the CPU time according to a simple
298 * round-robin policy.
300 * As a general rule to maximize responsiveness, compute-bound processes
301 * should be assigned negative priorities and tight, interactive processes
302 * should be assigned positive priorities.
304 * To avoid interfering with system background activities such as input
305 * processing, application processes should remain within the range -10
308 void proc_setPri(struct Process *proc, int pri)
310 if (proc->link.pri == pri)
313 proc->link.pri = pri;
315 if (proc != CurrentProcess)
318 //TODO: re-enqueue process
322 #endif // CONFIG_KERN_PRI
325 * Terminate the current process
329 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
331 #if CONFIG_KERN_MONITOR
332 monitor_remove(CurrentProcess);
337 * The following code is BROKEN.
338 * We are freeing our own stack before entering proc_schedule()
339 * BAJO: A correct fix would be to rearrange the scheduler with
340 * an additional parameter which frees the old stack/process
341 * after a context switch.
343 if (CurrentProcess->flags & PF_FREESTACK)
344 heap_free(CurrentProcess->stack_base, CurrentProcess->stack_size);
345 heap_free(CurrentProcess);
348 #if (ARCH & ARCH_EMUL)
349 /* Reinsert process stack in free list */
350 PROC_ATOMIC(ADDHEAD(&StackFreeList, (Node *)CurrentProcess->stack_base));
353 * NOTE: At this point the first two words of what used
354 * to be our stack contain a list node. From now on, we
355 * rely on the compiler not reading/writing the stack.
357 #endif /* ARCH_EMUL */
359 CurrentProcess = NULL;
366 * Get the pointer to the current process
368 struct Process *proc_current(void)
370 return CurrentProcess;
374 * Get the pointer to the user data of the current process
376 iptr_t proc_currentUserData(void)
378 return CurrentProcess->user_data;