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3.2   Object Types

The following is an overview of the available object types (the built-in classes):

device

Each DML program defines a subclass of the device class, which can be instantiated as a configuration object in Simics.

attribute

An arbitrary Simics configuration-object attribute of the device. Many attributes are created automatically from the declaration of device members such as registers and connects, but it is possible to manually add other attributes as well. This can be used to provide synthetic information about the device for inspection, or as a simple programming interface. Attributes are typically saved automatically when a Simics checkpoint is created.

bank

A register bank. Banks make sets of registers accessible by placing them in an address space. Register banks can be individually mapped into Simics memory spaces by using a separate function number for each bank. The bank class is a subclass of group.

register

A register holds an integer value, and is generally used to model a hardware register. The width of a register is a nonzero number of bytes (a register may not be wider than 8 bytes). Registers may only occur within a bank (directly or indirectly). Registers divide the address space of a bank into discrete elements with non-overlapping addresses. Registers are used for communication via memory-mapped I/O, and also for storing device state in natural way. Sometimes it is useful to have registers that belong to a bank but are not mapped into its address space.

array of register

Register arrays are used for compact representation of related registers within the same bank.

field

A register can be further divided into fields on the bit level. Each such field can be accessed separately, both for reading and for writing. The fields of a register may not overlap.

group

Groups are generic container objects, and are mainly used to define logical groups of registers. See also bank.

array of group

Arrays of groups are useful for modeling repeated groups of registers.

connect

A connect object holds a reference to a Simics configuration object. (Typically, the connected object is expected to implement some particular Simics-interface.) An attribute with the same name is added to the device; thus, a connect is similar to a simple attribute object. Usually, initialization is done from outside the device, e.g., in a Simics configuration file.

array of connect

Connect-arrays make it easy to connect a whole array of objects.

interface

An interface object may only occur within a connect. It is used to declare a Simics-interface assumed to be implemented by the connected object. In many cases, the name of the interface is sufficient, and the body of the object can be left empty.

implement

An implement object is used to define a Simics-interface that the device implements. The methods defined within the implement must correspond to the functions of the interface.

event

An event object is an encapsulation of a Simics event that can be posted on a time or step queue. Almost all objects can have event members, except events themselves, and objects of type field and implement.

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