The concept of a "trigger resource" serves as a generalization of interrupts, enabling tasks to be resumed or restarted when a specific event occurs. Tasks can be registered with a trigger resource, and when the trigger resource is activated, the associated tasks are resumed or restarted. The gu_trigger_create function creates a trigger resource and allows associating an external interrupt with it. The gu_trigger_register_task function registers a task with a trigger resource. When the trigger resource is activated, it is disabled until all registered tasks that have been resumed or restarted transition to a waiting state for a new trigger. Tasks associated with a trigger resource enter a waiting state for the trigger when they finish execution. Additionally, the gu_trigger_wait function explicitly places a task into the waiting for the trigger state. Trigger resources can be associated with external events, such as hardware interrupts. In this case, all tasks registered with the trigger resource behave as Interrupt Service Routines (ISRs). Importantly, these tasks operate independently of each other, ensuring that multiple tasks can be associated with a single trigger resource. Trigger resources can also be triggered from tasks' code using the gu_trigger_release function. When triggered, all registered tasks will be resumed or restarted if the trigger resource is enabled. The gu_trigger_enable function enables a trigger resource, while the gu_trigger_disable function disables it.

Enable and disable hook functions #

The system provides flexibility in handling events by allowing hook functions to be executed when trigger resources are enabled or disabled. The gu_trigger_enable_hook function allows configuring a function to be executed before a trigger resource is enabled, while gu_trigger_disable_hook configures a function to be executed after the trigger resource is disabled. These hook functions are intended to execute specific code associated with the devices associated with the trigger resource.

Trigger flexibility #

The system provides flexibility in handling events by allowing hook functions to be executed when trigger resources are enabled or disabled. The gu_trigger_enable_hook function allows configuring a function to be executed before a trigger resource is enabled, while gu_trigger_disable_hook configures a function to be executed after the trigger resource is disabled. These hook functions are intended to execute specific code associated with the devices associated with the trigger resource. Trigger resources offer a flexible approach to handling system events, overcoming the limitations of traditional interrupts. For example, Universal Asynchronous Receiver/Transmitter (UART) devices, like many peripherals, typically group various internal events, such as input buffer full and output buffer empty, into a single hardware interrupt signal. This requires the UART driver to determine which event triggered the interrupt and execute the corresponding code. With trigger resources, a trigger resource can be associated with the UART interrupt signal. The task code registered to this trigger resource then checks which event triggered the interrupt: input buffer full, output buffer empty, or both. If the input buffer is full, the trigger resource is activated, resuming all tasks associated with reading from the buffer. This example demonstrates the flexibility of trigger resources by allowing for the specific handling of individual events within a single interrupt signal. This approach eliminates the need for complex logic within the interrupt service routine to determine the cause of the interrupt and execute the appropriate actions. By leveraging trigger resources and hook functions, the GeMRTOS system provides a powerful and flexible mechanism for managing system events, enhancing the efficiency and modularity of the overall system design.

If the output buffer is empty, the system activates a trigger resource associated with writing tasks. This allows for an arbitrary number of reading and writing tasks to operate concurrently without interfering with each other. The trigger resource associated with the input buffer should have defined hook functions to enable and disable the input buffer full event. Similarly, the trigger resource associated with the output buffer should have defined hook functions to enable and disable the output buffer empty event. This approach allows for the virtualization and generalization of both internal and external events through the use of trigger resources.