doc: Edit microkernel_fifos for consistent .rst style and formatting.

Making all the files in this section consistent with :dfn: in the intro
paragraph, API headings, present-tense verbs in APIs, parallel wording.

Change-Id: I5259c443076b1ac6602352dab42d35d5aca6e5b5
Signed-off-by: L.S. Cook <leonax.cook@intel.com>

doc/kernel/microkernel/microkernel_fifos.rst

@@ -6,27 +6,29 @@ FIFOs
 Concepts
 ********
 
-The microkernel's FIFO object type is an implementation of a traditional
+The microkernel's :dfn:`FIFO` object type is an implementation of a traditional
 first in, first out queue.
 
 A FIFO allows tasks to asynchronously send and receive fixed-size data items.
-Each FIFO has an associated ring buffer for holding data items that have been
+Each FIFO has an associated ring buffer used to hold data items that have been
 sent but not yet received.
 
-Any number of FIFOs can be defined in a microkernel system. Each FIFO has a
-name that uniquely identifies it. In addition, a FIFO defines the size of
-the data items it handles and the maximum number of data items that can be
-queued in its ring buffer, both of which must be greater than zero.
+Any number of FIFOs can be defined in a microkernel system. Each FIFO needs:
+
+* A **name** that uniquely identifies it.
+* A **maximum quantity** of data items that can be queued in its ring buffer.
+* The **data item size**, measured in bytes, of each data item it can handle.
+
 
 A task sends a data item by specifying a pointer to an area containing the data
 to be sent; the size of the data area must equal the FIFO's data item size.
-The data is given directly to a receiving task (if one is waiting) or copied
-to the FIFO's ring buffer (if space is available). When a FIFO is full
-the sending task may choose to wait for space to become available.
+The data is either given directly to a receiving task (if one is waiting), or
+copied to the FIFO's ring buffer (if space is available). When a FIFO is full,
+the sending task can wait for space to become available.
 
 Any number of tasks may wait on a full FIFO simultaneously; when space for
-a data item becomes available it is given to the highest priority task that
-has waited the longest.
+a data item becomes available, that space is given to the highest-priority
+task that has waited the longest.
 
 A task receives a data item by specifying a pointer to an area to receive
 the data; the size of the receiving area must equal the FIFO's data item size.
@@ -50,7 +52,7 @@ anonymous manner.
    copying the data. The microkernel's memory map and memory pool object
    types can be helpful for data transfers of this sort.
 
-   A synchronous transfer can be achieved using the microkernel's mailbox
+   A synchronous transfer can be achieved by using the microkernel's mailbox
    object type.
 
    A non-anonymous transfer can be achieved by having the sending task
@@ -81,7 +83,8 @@ The following parameters must be defined:
 Public FIFO
 -----------
 
-Define the FIFO in the application's .MDEF file using the following syntax:
+Define the FIFO in the application's :file:`.MDEF` file with the
+following syntax:
 
 .. code-block:: console
 
@@ -114,7 +117,7 @@ For example, the following code defines a private FIFO named ``PRIV_FIFO``.
 
    DEFINE_FIFO(PRIV_FIFO, 10, 12);
 
-To utilize this FIFO from a different source file use the following syntax:
+To access this FIFO from a different source file, use the following syntax:
 
 .. code-block:: c
 
@@ -150,8 +153,8 @@ can't keep up, throw away all existing data so newer data can be saved.
 Example: Reading from a FIFO
 ============================
 
-This code uses a FIFO to process data items from generated by
-one or more producing tasks.
+This code uses a FIFO to process data items generated by one or more
+producing tasks.
 
 .. code-block:: c
 
@@ -171,18 +174,20 @@ one or more producing tasks.
 APIs
 ****
 
-The following APIs for a microkernel FIFO are provided by
-:file:`microkernel.h`:
+FIFO APIs provided by :file:`microkernel.h`
+===========================================
 
 :c:func:`task_fifo_put()`
-   Writes item to a FIFO, or wait for a specified time period if it is full.
+   Write item to a FIFO, or wait for a specified time period if the FIFO is
+   full.
 
 :c:func:`task_fifo_get()`
-   Reads item from a FIFO, or wait for a specified time period if it is empty.
+   Read item from a FIFO, or wait for a specified time period if the FIFO is
+   empty.
 
 :c:func:`task_fifo_purge()`
-   Discards all items in a FIFO and unblock any tasks
-   waiting to read or write an item.
+   Discard all items in a FIFO and unblock any tasks waiting to read or write
+   an item.
 
 :c:func:`task_fifo_size_get()`
-   Reads the number of items currently in a FIFO.
+   Read the number of items currently in a FIFO.