+++ /dev/null
-/**
- * \file
- * <!--
- * This file is part of BeRTOS.
- *
- * Bertos 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
- * (at your option) 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 St, Fifth Floor, Boston, MA 02110-1301 USA
- *
- * As a special exception, you may use this file as part of a free software
- * library without restriction. Specifically, if other files instantiate
- * templates or use macros or inline functions from this file, or you compile
- * this file and link it with other files to produce an executable, this
- * file does not by itself cause the resulting executable to be covered by
- * the GNU General Public License. This exception does not however
- * invalidate any other reasons why the executable file might be covered by
- * the GNU General Public License.
- *
- * Copyright 2004 Develer S.r.l. (http://www.develer.com/)
- * Copyright 1999, 2000, 2001 Bernardo Innocenti <bernie@develer.com>
- *
- * -->
- *
- * \brief IPC signals implementation.
- *
- * Signals are a low-level IPC primitive. A process receives a signal
- * when some external event has happened. Like interrupt requests,
- * signals do not carry any additional information. If processing a
- * specific event requires additional data, the process must obtain it
- * through some other mechanism.
- *
- * Despite the name, one shouldn't confuse these signals with POSIX
- * signals. POSIX signals are usually executed synchronously, like
- * software interrupts.
- *
- * Signals are very low overhead. Using them exclusively to wait
- * for multiple asynchronous events results in very simple dispatch
- * logic with low processor and resource usage.
- *
- * The "event" module is a higher-level interface that can optionally
- * deliver signals to processes. Messages provide even higher-level
- * IPC services built on signals. Semaphore arbitration is also
- * implemented using signals.
- *
- * In this implementation, each process has a limited set of signal
- * bits (usually 32) and can wait for multiple signals at the same
- * time using sig_wait(). Signals can also be polled using sig_check(),
- * but a process spinning on its signals usually defeats their purpose
- * of providing a multitasking-friendly infrastructure for event-driven
- * applications.
- *
- * Signals are like flags: they are either active or inactive. After an
- * external event has delivered a particular signal, it remains raised until
- * the process acknowledges it using either sig_wait() or sig_check().
- * Counting signals is not a reliable way to count how many times a
- * particular event has occurred, because the same signal may be
- * delivered twice before the process can notice.
- *
- * Any execution context, including an interrupt handler, can deliver
- * a signal to a process using sig_signal(). Multiple independent signals
- * may be delivered at once with a single invocation of sig_signal(),
- * although this is rarely useful.
- *
- * \section signal_allocation Signal Allocation
- *
- * There's no hardcoded mapping of specific events to signal bits.
- * The meaning of a particular signal bit is defined by an agreement
- * between the delivering entity and the receiving process.
- * For instance, a terminal driver may be designed to deliver
- * a signal bit called SIG_INT when it reads the CTRL-C sequence
- * from the keyboard, and a process may react to it by quitting.
- *
- * \section sig_single SIG_SINGLE
- *
- * The SIG_SINGLE bit is reserved as a convenient shortcut in those
- * simple scenarios where a process needs to wait on just one event
- * synchronously. By using SIG_SINGLE, there's no need to allocate
- * a specific signal from the free pool. The constraints for safely
- * accessing SIG_SINGLE are:
- * - The process MUST sig_wait() exclusively on SIG_SINGLE
- * - SIG_SIGNAL MUST NOT be left pending after use (sig_wait() will reset
- * it automatically)
- * - Do not sleep between starting the asynchronous task that will fire
- * SIG_SINGLE, and the call to sig_wait().
- * - Do not call system functions that may implicitly sleep, such as
- * timer_delayTickes().
- *
- * \version $Id$
- *
- * \author Bernardo Innocenti <bernie@develer.com>
- */
-
-#include "signal.h"
-
-#include <cfg/debug.h>
-#include <drv/timer.h>
-#include <kern/proc.h>
-#include <kern/proc_p.h>
-
-
-#if CONFIG_KERN_SIGNALS
-
-/**
- * Check if any of the signals in \a sigs has occurred and clear them.
- * \return the signals that have occurred.
- */
-sigmask_t sig_check(sigmask_t sigs)
-{
- sigmask_t result;
- cpuflags_t flags;
-
- IRQ_SAVE_DISABLE(flags);
- result = CurrentProcess->sig_recv & sigs;
- CurrentProcess->sig_recv &= ~sigs;
- IRQ_RESTORE(flags);
-
- return result;
-}
-
-
-/**
- * Sleep until any of the signals in \a sigs occurs.
- * \return the signal(s) that have awoken the process.
- */
-sigmask_t sig_wait(sigmask_t sigs)
-{
- sigmask_t result;
- cpuflags_t flags;
-
- IRQ_SAVE_DISABLE(flags);
-
- /* Loop until we get at least one of the signals */
- while (!(result = CurrentProcess->sig_recv & sigs))
- {
- /* go to sleep and proc_schedule() another process */
- CurrentProcess->sig_wait = sigs;
- proc_schedule();
-
- /* When we come back here, a signal must be arrived */
- ASSERT(!CurrentProcess->sig_wait);
- ASSERT(CurrentProcess->sig_recv);
- }
-
- /* Signals found: clear them and return */
- CurrentProcess->sig_recv &= ~sigs;
-
- IRQ_RESTORE(flags);
- return result;
-}
-
-/**
- * Sleep until any of the signals in \a sigs or \a timeout ticks elapse.
- * If the timeout elapse a SIG_TIMEOUT is added to the received signal(s).
- * \return the signal(s) that have awoken the process.
- * \note Caller must check return value to check which signal awoke the process.
- */
-sigmask_t sig_waitTimeout(sigmask_t sigs, ticks_t timeout)
-{
- Timer t;
- sigmask_t res;
- cpuflags_t flags;
-
- ASSERT(!sig_check(SIG_TIMEOUT));
- ASSERT(!(sigs & SIG_TIMEOUT));
- /* IRQ are needed to run timer */
- ASSERT(IRQ_ENABLED());
-
- timer_set_event_signal(&t, proc_current(), SIG_TIMEOUT);
- timer_setDelay(&t, timeout);
- timer_add(&t);
- res = sig_wait(SIG_TIMEOUT | sigs);
-
- IRQ_SAVE_DISABLE(flags);
- /* Remove timer if sigs occur before timer signal */
- if (!(res & SIG_TIMEOUT) && !sig_check(SIG_TIMEOUT))
- timer_abort(&t);
- IRQ_RESTORE(flags);
- return res;
-}
-
-
-/**
- * Send the signals \a sigs to the process \a proc.
- * The process will be awoken if it was waiting for any of them.
- *
- * \note This call is interrupt safe.
- */
-void sig_signal(Process *proc, sigmask_t sigs)
-{
- cpuflags_t flags;
- IRQ_SAVE_DISABLE(flags);
-
- /* Set the signals */
- proc->sig_recv |= sigs;
-
- /* Check if process needs to be awoken */
- if (proc->sig_recv & proc->sig_wait)
- {
- /* Wake up process and enqueue in ready list */
- proc->sig_wait = 0;
- SCHED_ENQUEUE(proc);
- }
-
- IRQ_RESTORE(flags);
-}
-
-#endif /* CONFIG_KERN_SIGNALS */
-
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