Embedded Software for SoC - Grupo de Mecatrônica EESC/USP

144 Chapter 11
5. CONVERSION OF SPECC DESCRIPTION
This section discusses the conversion technique from a SpecC description to
a device, a device driver and the interface in between. For the conversion of
a device driver and interface, we use evaluation point (2) described in section
3. The partition of the software and the hardware is the byte channel. The
description of the layer above the byte channel is converted into a device
driver description in C-language program and the description of the layer
below the byte channel is converted into a device description in VHDL and
the byte channel is converted into an interface in between. The conversions
are made mechanically where possible. The converted software part (device
driver) in C-language is linked with
specification real-time kernel.
The converted hardware part (device) in VHDL is synthesized for FPGA. The
behavior of the implementations are verified using a prototype system with
processor and FPGA. The results show that the behaviors of the implementations
are correct.
5.1. Device driver
In the SIO system, the object of device driver conversion is the description
ranging from the PPP generation and analysis behavior to the byte transmit
and receive behavior.
The SpecC behaviors can be classified into two: parallel execution and used
functionally. Behaviors executed in parallel are converted into tasks and the
other behaviors are converted into functions. Specifically, behaviors that are
executed in parallel according to the par statement, are converted to tasks. In
order to suspend the behavior until all the other behaviors executed through
the par statement have been completed, the parent task executing the par
statement is moved to the waiting state until all child tasks have completed
execution.
The try-trap-interrupt statement is converted into a description that uses
the task exception-handling function of
The task corresponding
to the behavior described in the try statement block is generated and an
exception demand to a task realizes the event. The exception handling routine
calls functions that are converted from the behavior described in the trap
statement block and the interrupt statement block. Other behaviors such as
behaviors executed sequentially and behaviors within the fsm statement used
to describe FSM are converted into functions. In the SIO system, the PPP
generation and analysis behavior and the byte transmit and receive behavior
are each converted to one task since they are executed in parallel and do not
call any other behavior.
A channel can be mechanically converted into a software by realizing the
atomic executions of methods encapsulated in channels, event triggers (notify
statement) and suspension of execution (wait statement) using semaphores
and eventflags provided in However, since the provides