Intrinsics

Pollen has several different kinds of intrinsics: a set of application lifecycle intrinsics, as well as intrinsics for sleep wake, assert and the name of the currently executing unit.

Pollen intrinsics provide common interfaces and protocols that applications can rely on yet they are customizable for variable hardware and software requirements.

Application Lifecycle Intrinsics

Every device application has a lifecycle. At each stage of the lifecycle the application may need to perform critical operations to ensure a proper execution environment. For example, upon applying power to the device, the microcontroller is reset at which time it must be configured properly to ensure the rest of the application can execute. Most device applications are intended to run perpetually with a power-off condition indicating failure. However, some applications require the ability to be shutdown and they may need specific operations performed during the shutdown process.

Pollen supports a set of intrinsic functions which serve as entry-points for developers into a module’s lifecycle at runtime. Functionality implemented in these intrinsics is commonly found in existing embedded applications although where it resides and how it is integrated into an application’s structure varies with the application. Having these entry points standardized in Pollen with knowledge of their invocation at specific points of runtime makes understanding application functionality more straightforward.

The application lifecycle intrinsic functions defined by Pollen are pollen.reset(), pollen.run(), pollen.shutdown(), and pollen.ready().

Startup: Initialization with Intrinsics and Constructors

The startup initialization intrinsics are pollen.reset(), pollen.ready(), and pollen.run().

This is the order of initialization:

• Upon powering up the microcontroller, the first function called is pollen.reset().
• Then each module constructor is called. (The order in which module constructors are executed is undefined.)
• After all constructors have completed, pollen.ready() is called. Thus an implementation of pollen.ready() can perform any cross module initialization which requires that each individual module has already been initialized.
• Finally pollen.run() executes and the application starts.

For both pollen.reset() and pollen.ready() system defined defaults exist. If the user defines one it will take precedence.

For pollen.run() there is no default and the user must define one in the top level module. (Note pollen.run() is also where the pollen application startup code is generated.)

Shutdown

Since the majority of embedded systems are intended to operate indefinitely, the intrinsic pollen.shutdown() can be used to gracefully enter fail states should they be encountered at runtime.

For pollen.shutdown(), a system defined default exists. If the user defines one it will take precedence.

Only one pollen.shutdown() can be defined.

Other Intrinsics

Sleep Wake

The two sleep wake constructors are pollen.sleep() and pollen.wake(). They do not have default implementations. You can define a module that implements these functions and then bind it to the SleepWakeProtocol:

 pollen.sleepWakeProtocol := SleepWakeImpl

This binding can occur anywhere and then the functions pollen.sleep() and pollen.wake() are available everywhere.

Unitname

It can be useful to have a variable that contains the name of the currently executing unit. pollen.unitname is that variable. It is an intrinsic string variable which holds that name. It can be used the way any string variable could be used. It is only generated if accessed and it does not need to be declared.

Assert

The assert intrinsic takes the form pollen.assert(condition, message). The condition is a conditional expression that is tested at runtime. If it is true then the message is output.

For assertions to be in effect the -a option has to be passed to the Pollen translator. In addition the print protocol must be bound to a print implementation. If these conditions are not satisfied the assert is a noop.