pSOSystem System Calls - Read

pSOS+ System Calls as_send
as_send Sends asynchronous signals to a task.
#include
unsigned long as_send(
unsigned long tid, /* target task ID */
unsigned long signals /* bit-encoded signal list */
)
Description
Arguments
Return Value
This system call sends asynchronous signals to a task. The purpose of these signals
is to force a task to break from its normal flow of execution and execute its
Asynchronous Signal Routine (ASR).
Asynchronous signals are like software interrupts, with ASRs taking on the role of
ISRs. Unlike an interrupt, which is serviced almost immediately, an asynchronous
signal does not immediately affect the state of the task. An as_send() call is
serviced only when the task is next dispatched to run (and that depends on the
state of the task and its priority).
Each task has 32 signals. These signals are encoded bit-wise in a single long word.
Bits 31 through 16 are reserved for internal system use, and bits 15 through 0 are
available for user-specific purposes.
Like events, signals are neither queued nor counted. For example, if three identical
signals are sent to a task before its ASR has a chance to execute, the three signals
have the same effect as one.
tid Specifies the task to receive the signals.
signals Contains the bit-encoded signals.
This system call returns 0 on success, or an error code on failure.
pSOSystem System Calls 1-9
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