Datasheet

Writing ARMulator models

3.2 Writing a new peripheral model

This section contains the following subsections:

• Using a sample model as a template

• Return values

• Initialization, finalization, and state macros on page 3-6

• Registering your model on page 3-6.

3.2.1 Using a sample model as a template

To write a new model, the best procedure is to copy one of the supplied models and then

edit the copy. To do this:

1. Select which model is closest to the model you want to write. This might be, for

example, Timer.

2. Copy the source file, in this case

timer.c

, with a new name such as

mymodel.c

3. Copy the make subdirectory, in this case

timer.b

, with a corresponding new name,

in this case

mymodel.b

4. Find the

Makefile

for your model (see Location of files on page 3-2).

Load

Makefile

into a text editor and change all instances of

timer

mymodel

You can now edit

MyModel

3.2.2 Return values

A model must return one of the following states for memory accesses:

PERIP_OK

If the model is able to service the request.

PERIP_BUSY

If a memory access requires wait-states. A model must not return

this state to a debugger access.

PERIP_DABORT

If a peripheral asserts the DABORT signal on the bus.

PERIP_NODECODE

If the model has been called with an address which belongs

to it, but which has no meaning to it. The memory model handles

the call as a memory access.