X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=kern%2Fsignal.c;h=71ccf67ada7dd6090ecc5a1420a7580567dda67d;hb=HEAD;hp=31cf3b7e2ca24b42db71f2ebd7bc7832d0a1ee7c;hpb=80041e65dca139a263d386ac7a64b25e054cd637;p=bertos.git diff --git a/kern/signal.c b/kern/signal.c deleted file mode 100644 index 31cf3b7e..00000000 --- a/kern/signal.c +++ /dev/null @@ -1,207 +0,0 @@ -/** - * \file - * - * - * \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. - * - * 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 distinct signals - * may be delivered at once with a single invocation of sig_signal(), - * although this is rarely useful. - * - * 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 written 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. - * - * The SIG_SINGLE bit is reserved for a special purpose (this is - * more a suggestion than a constraint). When a process wants - * wait for a single event on the fly, it needs not allocate a - * free signal from its pool. Instead, SIG_SINGLE can be used - * - * 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. - * - * 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. - * - * - * \version $Id$ - * - * \author Bernardo Innocenti - */ - -#include "signal.h" - -#include -#include -#include -#include - - -#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 */ -