f81ee6efdd
Moves the Nanokernel Object documentation to a new Nanokernel Services section within the Kernel Primer. Labels, cross-references, figures, headings and filenames were updated to reflect the new structure. Change-Id: I04f97e712d78cd211a8ed1315f86895a51affa01 Signed-off-by: Rodrigo Caballero <rodrigo.caballero.abraham@intel.com>
100 lines
5.0 KiB
ReStructuredText
100 lines
5.0 KiB
ReStructuredText
.. _nanokernel_data:
|
|
|
|
Data Passing Services
|
|
#####################
|
|
|
|
This section contains the information about all data passing services available in the nanokernel.
|
|
|
|
Nanokernel FIFO
|
|
***************
|
|
|
|
Definition
|
|
==========
|
|
|
|
|
|
The FIFO object is defined in :file:`kernel/nanokernel/nano_fifo.c`.
|
|
This is a linked list of memory that allows the caller to store data of
|
|
any size. The data is stored in first-in-first-out order.
|
|
|
|
Function
|
|
========
|
|
|
|
|
|
Multiple processes can wait on the same FIFO object. Data is passed to
|
|
the first fiber that waited on the FIFO, and then to the background
|
|
task if no fibers are waiting. Through this mechanism the FIFO object
|
|
can synchronize or communicate between more than two contexts through
|
|
its API. Any ISR, fiber, or task can attempt to get data from a FIFO
|
|
without waiting on the data to be stored.
|
|
|
|
.. note::
|
|
|
|
The FIFO object reserves the first WORD in each stored memory
|
|
block as a link pointer to the next item. The size of the WORD
|
|
depends on the platform and can be 16 bit, 32 bit, etc.
|
|
|
|
Application Program Interfaces
|
|
==============================
|
|
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| Context | Interfaces |
|
|
+================================+================================================================+
|
|
| **Initialization** | :c:func:`nano_fifo_init()` |
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| **Interrupt Service Routines** | :c:func:`nano_isr_fifo_get()`, :c:func:`nano_isr_fifo_put()` |
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| **Fibers** | :c:func:`nano_fiber_fifo_get()`, |
|
|
| | :c:func:`nano_fiber_fifo_get_wait()`, |
|
|
| | :c:func:`nano_fiber_fifo_put()` |
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| **Tasks** | :c:func:`nano_task_fifo_get()`, |
|
|
| | :c:func:`nano_task_fifo_get_wait()`, |
|
|
| | :c:func:`nano_task_fifo_put()` |
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
|
|
Nanokernel LIFO Object
|
|
**********************
|
|
|
|
Definition
|
|
==========
|
|
|
|
The LIFO is defined in :file:`kernel/nanokernel/nano_lifo.c`. It
|
|
consists of a linked list of memory blocks that uses the first word in
|
|
each block as a next pointer. The data is stored in last-in-first-out
|
|
order.
|
|
|
|
Function
|
|
========
|
|
|
|
When a message is added to the LIFO, the data is stored at the head of
|
|
the list. Messages taken off the LIFO object are taken from the head.
|
|
|
|
The LIFO object requires the first 32-bit word to be empty in order to
|
|
maintain the linked list.
|
|
|
|
The LIFO object does not store information about the size of the
|
|
messages.
|
|
|
|
The LIFO object remembers one waiting context. When a second context
|
|
starts waiting for data from the same LIFO object, the first context
|
|
remains waiting and never reaches the runnable state.
|
|
|
|
Application Program Interfaces
|
|
==============================
|
|
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| Context | Interfaces |
|
|
+================================+================================================================+
|
|
| **Initialization** | :c:func:`nano_lifo_init()` |
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| **Interrupt Service Routines** | :c:func:`nano_isr_lifo_get()`, |
|
|
| | :c:func:`nano_isr_lifo_put()` |
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| **Fibers** | :c:func:`nano_fiber_lifo_get()`, |
|
|
| | :c:func:`nano_fiber_lifo_get_wait()`, |
|
|
| | :c:func:`nano_fiber_lifo_put()` |
|
|
+--------------------------------+----------------------------------------------------------------+
|
|
| **Tasks** | :c:func:`nano_task_lifo_get()`, |
|
|
| | :c:func:`nano_task_lifo_get_wait()`, |
|
|
| | :c:func:`nano_task_lifo_put()` |
|
|
+--------------------------------+----------------------------------------------------------------+ |